Overview

This module is a component for use in pixl-server. It implements a simple web server with support for both HTTP and HTTPS, serving static files, and hooks for adding custom URI handlers.

Table of Contents

• Usage
• Configuration
  • http_port
  • http_alt_ports
  • http_bind_address
  • http_htdocs_dir
  • http_max_upload_size
  • http_temp_dir
  • http_static_ttl
  • http_static_index
  • http_server_signature
  • http_compress_text
  • http_regex_text
  • http_regex_json
  • http_response_headers
  • http_code_response_headers
  • http_timeout
  • http_request_timeout
  • http_keep_alives
    • default
    • request
    • close
  • http_keep_alive_timeout
  • http_socket_prelim_timeout
  • http_max_requests_per_connection
  • http_gzip_opts
  • http_enable_brotli
  • http_brotli_opts
  • http_default_acl
  • http_log_requests
  • http_log_request_details
  • http_log_body_max
  • http_regex_log
  • http_log_perf
  • http_perf_threshold_ms
  • http_perf_report
  • http_recent_requests
  • http_max_connections
  • http_max_concurrent_requests
  • http_max_queue_length
  • http_max_queue_active
  • http_queue_skip_uri_match
  • http_clean_headers
  • http_log_socket_errors
  • http_full_uri_match
  • http_flatten_query
  • http_req_max_dump_enabled
  • http_req_max_dump_dir
  • http_req_max_dump_debounce
  • http_public_ip_offset
  • https
  • https_port
  • https_alt_ports
  • https_cert_file
  • https_key_file
  • https_ca_file
  • https_force
  • https_header_detect
  • https_timeout
• Custom URI Handlers
  • Access Control Lists
  • Internal File Redirects
  • Static Directory Handlers
  • Sending Responses
    • Standard Response
    • Custom Response
    • JSON Response
    • Non-Response
  • args
    • args.request
    • args.response
    • args.ip
    • args.ips
    • args.query
    • args.params
      • Standard HTTP POST
      • JSON REST POST
      • Unknown POST
    • args.files
    • args.cookies
    • args.perf
    • args.server
    • args.id
  • Request Filters
• Transaction Logging
  • Request Detail Logging
  • Performance Threshold Logging
    • Including Diagnostic Reports
  • Including Custom Metrics
• Stats
  • The Server Object
  • The Stats Object
  • The Listeners Object
  • The Sockets Object
  • The Recent Object
  • The Queue Object
  • Stats URI Handler
• Misc
  • Determining HTTP or HTTPS
  • Self-Referencing URLs
  • Custom Method Handlers
  • Let's Encrypt SSL Certificates
  • Request Max Dump
• License

Usage

Use npm to install the module:

npm install pixl-server pixl-server-web

Here is a simple usage example. Note that the component's official name is WebServer, so that is what you should use for the configuration key, and for gaining access to the component via your server object.

const PixlServer = require('pixl-server');
let server = new PixlServer({
	
	__name: 'MyServer',
	__version: "1.0",
	
	config: {
		"log_dir": "/let/log",
		"debug_level": 9,
		
		"WebServer": {
			"http_port": 80,
			"http_htdocs_dir": "/let/www/html"
		}
	},
	
	components: [
		require('pixl-server-web')
	]
	
});

server.startup( function() {
	// server startup complete
	
	server.WebServer.addURIHandler( '/my/custom/uri', 'Custom Name', function(args, callback) {
		// custom request handler for our URI
		callback( 
			"200 OK", 
			{ 'Content-Type': "text/html" }, 
			"Hello this is custom content!\n" 
		);
	} );
} );

Notice how we are loading the pixl-server parent module, and then specifying pixl-server-web as a component:

components: [
	require('pixl-server-web')
]

This example is a very simple web server configuration, which will listen on port 80 and serve static files out of /let/www/html. However, if the URI is /my/custom/uri, a custom callback function is fired and can serve up any response it wants. This is a great way to implement an API.

Configuration

The configuration for this component is set by passing in a WebServer key in the config element when constructing the PixlServer object, or, if a JSON configuration file is used, a WebServer object at the outermost level of the file structure. It can contain the following keys:

http_port

This is the main port to listen on. The standard web port is 80, but note that only the root user can listen on ports below 1024.

http_alt_ports

If you would like to have the server listen on additional ports, add them here as an array. Example:

{
	"http_port": 80,
	"http_alt_ports": [ 3000, 8080 ]
}

http_bind_address

Optionally specify an exact local IP address to bind the listeners to. By default this binds to all available addresses on the machine. Example:

{
	"http_bind_address": "127.0.0.1"
}

This example would cause the server to only listen on localhost, and not any external network interface.

http_htdocs_dir

This is the path to the directory to serve static files out of, e.g. /let/www/html.

http_max_upload_size

This is the maximum allowed upload size. If uploading files, this is a per-file limit. If submitting raw data, this is an overall POST content limit. The default is 32MB.

http_temp_dir

This is where file uploads will be stored temporarily, until they are renamed or deleted. If omitted, this defaults to the operating system's temp directory, as returned from os.tmpDir().

http_static_ttl

This is the TTL (time to live) value to pass on the Cache-Control response header. This causes static files to be cached for a number of seconds. The default is 0 seconds.

http_static_index

This sets the filename to look for when directories are requested. It defaults to index.html.

http_server_signature

This is a string to send back to the client with every request, as the Server HTTP response header. This is typically used to declare the web server software being used. The default is WebServer.

http_compress_text

This is a boolean indicating whether or not to compress text responses using zlib software compression in Node.js. The default is false. The compression format is chosen automatically based on the Accept-Encoding request header sent from the client. The supported formats are Brotli (see http_enable_brotli), Gzip and Deflate, chosen in that order.

You can force compression on an individual response basis, by including a X-Compress: 1 response header in your URI handler code. The web server will detect this outgoing header and force-enable compression on the data, regardless of the http_compress_text or http_regex_text settings. Note that it still honors the client Accept-Encoding header, and will only enable compression if this request header is present and contains a supported scheme.

Note: The legacy http_gzip_text property is still supported, and is now a shortcut for http_compress_text.

http_regex_text

This is a regular expression string which is compared against the Content-Type response header. When this matches, and http_compress_text is enabled, this will kick in compression. It defaults to (text|javascript|json|css|html).

http_regex_json

This is a regular expression string used to determine if the incoming POST request contains JSON. It is compared against the Content-Type request header. The default is (javascript|js|json).

http_response_headers

This param allows you to send back any additional custom HTTP headers with each response. Set the param to an object containing keys for each header, like this:

{
	"http_response_headers": {
		"X-My-Custom-Header": "12345",
		"X-Another-Header": "Hello"
	}
}

http_code_response_headers

This property allows you to include conditional response headers, based on the HTTP response code. For example, you can instruct the web server to send back a custom header with 404 (File Not Found) responses, like this:

{
	"http_code_response_headers": {
		"404": {
			"X-Message": "And don't come back!"
		}
	}
}

An actual useful case would be to include a Retry-After header with all 429 (Too Many Requests) responses, like this:

{
	"http_code_response_headers": {
		"429": {
			"Retry-After": "10"
		}
	}
}

This would give a hint to clients when they receive a 429 (Too Many Requests) response from the web server, that they should wait 10 seconds before trying again.

http_timeout

This sets the idle socket timeout for all incoming HTTP requests, in seconds. If omitted, the Node.js default is 120 seconds. Example:

{
	"http_timeout": 120
}

This only applies to reading from sockets when data is expected. It is an idle read timeout on the socket itself, and doesn't apply to request handlers.

http_request_timeout

This property sets an actual hard request timeout for all incoming requests. If the total combined request processing, handling and response time exceeds this value, specified in seconds, then the request is aborted and a HTTP 408 Request Timeout response is sent back to the client. This defaults to 0 (disabled). Example use:

{
	"http_request_timeout": 300
}

Note that this includes request processing time (e.g. receiving uploaded data from a HTTP POST).

http_keep_alives

This controls the HTTP Keep-Alive behavior in the web server. There are three possible settings, which should be specified as a string:

default

{
	"http_keep_alives": "default"
}

This enables Keep-Alives for all incoming connections by default, unless the client specifically requests a close connection via a Connection: close header.

request

{
	"http_keep_alives": "request"
}

This disables Keep-Alives for all incoming connections by default, unless the client specifically requests a Keep-Alive connection by passing a Connection: keep-alive header.

close

{
	"http_keep_alives": "close"
}

This completely disables Keep-Alives for all connections. All requests result in the socket being closed after completion, and each socket only serves one single request.

http_keep_alive_timeout

This sets the HTTP Keep-Alive idle timeout for all sockets, measured in seconds. If omitted, the Node.js default is 5 seconds. See server.keepAliveTimeout for details. Example:

{
	"http_keep_alive_timeout": 5
}

http_socket_prelim_timeout

This sets a special preliminary timeout for brand new sockets when they are first connected, measured in seconds. If an HTTP request doesn't come over the socket within this timeout (specified in seconds), then the socket is hard closed. This timeout should always be set lower than the http_timeout if used. This defaults to 0 (disabled). Example use:

{
	"http_socket_prelim_timeout": 3
}

The idea here is to prevent certain DDoS-style attacks, where an attacker opens a large amount of TCP connections without sending any requests over them.

Note: Do not enable this feature if you attach a WebSocket server such as ws.

http_max_requests_per_connection

This allows you to set a maximum number of requests to allow per Keep-Alive connection. It defaults to 0 which means unlimited. If set, and the maximum is reached, a Connection: close header is returned, politely asking the client to close the connection. It does not actually hard-close the socket. Example:

{
	"http_max_requests_per_connection": 100
}

http_gzip_opts

This allows you to set various options for the automatic GZip compression in HTTP responses. Example:

{
	"http_gzip_opts": {
		"level": 6,
		"memLevel": 8
	}
}

Please see the Node Zlib Class Options for more details on what can be set here.

http_enable_brotli

Set this to true to enable Brotli compression support. The default is false (disabled). When enabled, and the client advertises support via the Accept-Encoding request header, and http_compress_text is enabled, and the response Content-Type matches the http_regex_text pattern, Brotli will be used.

Brotli is a newer compression format written by Google, which was added to Node.js in v10.16.0. With careful tuning (see below) you can produce equivalent payload sizes to Gzip but considerably faster (i.e. less CPU), or even up to ~20% smaller sizes than Gzip but much slower (i.e. more CPU).

http_brotli_opts

If http_enable_brotli is set to true, then you can set various options via the http_brotli_opts configuration property. Example:

{
	"http_brotli_opts": {
		"chunkSize": 16 * 1024,
		"mode": "text",
		"level": 4,
		"hint": 0
	}
}

See the Node Brotli Class Options for more details on what can be set here. Note that mode is a convenience shortcut for zlib.constants.BROTLI_PARAM_MODE (which can set to text, font or generic), level is a shortcut for zlib.constants.BROTLI_PARAM_QUALITY, and hint is a shortcut for zlib.constants.BROTLI_PARAM_SIZE_HINT.

http_default_acl

This allows you to configure the default ACL, which is only used for URI handlers that register themselves as private. To customize it, specify an array of IPv4 and/or IPv6 addresses, partials or CIDR blocks. It defaults to localhost plus the IPv4 private reserved and IPv6 private reserved ranges. Example:

{
	"http_default_acl": ["127.0.0.1", "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "::1/128", "fd00::/8", "169.254.0.0/16", "fe80::/10"]
}

See Access Control Lists below for more details.

http_log_requests

This boolean allows you to enable transaction logging in the web server. It defaults to false (disabled). See Transaction Logging below for details.

http_log_request_details

This boolean adds verbose detail in the transaction log. It defaults to false (disabled). See Transaction Logging below for details.

Note: This property only has effect if http_log_requests is enabled.

http_log_body_max

This property sets the maximum allowed request and response body length that can be logged, when http_log_request_details is enabled. If the request or response body length exceeds this amount, they will not be included in the transaction log.

Note: This property only has effect if http_log_request_details is enabled.

http_regex_log

If http_log_requests is enabled, this allows you to specify a regular expression to match against incoming request URIs. Only requests that match will be logged. It defaults to match all URIs (.+). See Transaction Logging below for details.

http_log_perf

This boolean allows you to enable performance threshold logging. It defaults to false (disabled). See Performance Threshold Logging below for details.

http_perf_threshold_ms

If http_log_perf is enabled, this allows you to specify the request elapsed time threshold in milliseconds. All requests equal to or longer will be logged. It defaults to 100 milliseconds. See Performance Threshold Logging below for details.

http_perf_report

This property allows you to include a complete or partial Node.js Diagnostic Report in your Performance Threshold Log. Specifically, you can set this to an array of report keys to include in the log data. See Including Diagnostic Reports below for details.

http_recent_requests

This integer specifies the number of recent requests to provide in the getStats() response. It defaults to 10. See Stats below for details.

http_max_connections

This integer specifies the maximum number of concurrent connections to allow. It defaults to 0 (no limit). If specified and the amount is exceeded, new incoming connections will be denied (socket force-closed without reading any data), and an error logged for each attempt (with error code maxconns).

http_max_concurrent_requests

This integer specifies the maximum number of concurrent requests to allow. It defaults to 0 (no limit). If more than the maximum allowed requests arrive in parallel, additional requests are queued, and processed as soon as slots become available. Requests are always processed in the order they were received.

The idea here is that you can set http_max_connections to a much higher value, for things like load balancers pre-opening connections or clients using a pool of keep-alive connections, but then only allow your application code to process a smaller amount of requests in parallel. For example:

{
	"http_max_connections": 2048,
	"http_max_concurrent_requests": 64
}

This would allow up to 2,048 concurrent connections (sockets) to be open at any given time, but only allow 64 active requests to run in parallel. If more than 64 requests came in at once, the remainder would be queued up, and processed as soon as other requests completed.

http_max_queue_length

The http_max_queue_length property is designed to work in conjunction with http_max_concurrent_requests. It specifies the maximum number of requests to allow in the queue, before rejecting new requests. It defaults to 0 (infinite). If the number of enqueued requests reaches this limit, then new incoming requests are immediately aborted with a HTTP 429 Too Many Requests response. An error is also logged with a 429 code in this case. Example error log entry:

[1587614950.774][2020-04-22 21:09:10][joe16.local][93307][WebServer][error][429][Queue is maxed out (100 pending reqs), denying request from: 127.0.0.1][{"ips":["127.0.0.1"],"uri":"/sleep?ms=500","headers":{"accept-encoding":"gzip, deflate, br","user-agent":"Overflow Test Agent 1.0","host":"localhost:3012","connection":"keep-alive"},"pending":100,"active":1024,"sockets":1175}]

The error log data column includes some additional information including the total requests pending, the number of concurrent active requests, and the number of open sockets.

http_max_queue_active

The http_max_queue_active property is designed to work in conjunction with http_max_connections, http_max_concurrent_requests and http_max_queue_length. It sets an upper maximum for number of concurrent active requests in the queue (i.e. concurrent active requests), before new ones are immediately rejected with an HTTP 429 response, without actually queueing up. This defaults to 0 (disabled), which means there is no limit imposed at the queue level.

The only reason you'd ever need to set this property is to handle a request overload situation by rejecting requests out of the queue via HTTP 429, rather than blocking them at the socket level (hard close), and also not allowing them to queue up (potential lag situation). Example configuration:

{
	"http_max_connections": 8192,
	"http_max_concurrent_requests": 1024,
	"http_max_queue_length": 1024,
	"http_max_queue_active": 1024
}

The idea here is that pixl-server-web will allow up to 1,024 concurrent requests, but additional requests beyond the maximum are still accepted and responded to with a nice HTTP 429 response, rather than the alternatives (i.e. allowing requests to queue up, possibly introducing unwanted lag, or performing a hard socket close). This works as long as the total concurrent sockets do not exceed the upper limit (8,192 in this case).

With both http_max_queue_length and http_max_queue_active set to non-zero values, the first limit reached aborts the request.

http_queue_skip_uri_match

The http_queue_skip_uri_match property is designed to work in conjunction with http_max_concurrent_requests. It allows you to specify a URI pattern match that will always skip over the queue and be processed immediately, regardless of limits. Using this feature you can allow things like health checks (possibly from a load balancer) to always be serviced, even during an overload situation. Example use:

{
	"http_queue_skip_uri_match": "^/server-status"
}

This property defaults to false (disabled).

http_clean_headers

This boolean enables HTTP response header cleansing. When set to true it will strip all illegal characters from your response header values, which otherwise could cause Node.js to crash. It defaults to false. The regular expression it uses is /([\x7F-\xFF\x00-\x1F\u00FF-\uFFFF])/g.

http_log_socket_errors

This boolean enables logging socket related errors, specifically sockets being closed unexpectedly (i.e. client closed socket, or some network error caused socket to abort). This defaults to true, meaning these will be logged as errors. If this generates too much log noise for your production stack, you can set the configuration property to false, which will only log a level 9 debug event. Example:

{
	"http_log_socket_errors": false
}

Example error log entry:

[1545121086.42][2018-12-18 00:18:06][myserver01.mycompany.com][29801][WebServer][error][socket][Socket closed unexpectedly: c43593][][][{"id":"c43593","proto":"http","port":80,"time_start":1545120267519,"num_requests":886,"bytes_in":652041,"bytes_out":1307291,"total_elapsed":818901,"url":"http://mycompany.com/example/url","ips":["1.1.1.1","2.2.2.2"]}]

http_full_uri_match

When this boolean is set to true, Custom URI Handlers will match against the full incoming URI, including the query string. By default this is disabled, meaning URIs are only matched using their path. Example:

{
	"http_full_uri_match": true
}

http_flatten_query

By default, we use the Node.js core Query String module to parse query strings. This module handles duplicate query params by converting them to arrays. For example, an incoming URI such as /something?foo=bar1&foo=bar2&name=joe would produce the following args.query object:

{
	"foo": ["bar1", "bar2"],
	"name": "joe"
}

However, if you set http_flatten_query to true in your configuration, the web server will "flatten" query string parameters, so that duplicate keys will be combined into one, with the latter prevailing. Example:

{
	"foo": "bar2",
	"name": "joe"
}

http_req_max_dump_enabled

When this boolean is set to true, the Request Max Dump system is enabled. This will produce a JSON dump file when the web server is maxed out on requests.

http_req_max_dump_dir

When the Request Max Dump system is enabled, the http_req_max_dump_dir property sets the directory path where JSON dump files are dropped. The directory will be created if needed.

http_req_max_dump_debounce

When the Request Max Dump system is enabled, the http_req_max_dump_debounce property sets how many seconds should elapse between dumps, as to not overwhelm the filesystem.

http_public_ip_offset

This controls how args.ip is chosen from the list of IP addresses in args.ips for each incoming request. By default, the client IP is chosen by scanning the list from left to right, and selecting the first non-private IP. However, modern wisdom suggests that alternate selection logic may be more desirable to find the true public IP.

By setting http_public_ip_offset to an integer value, you can select exactly which IP to select from the list. Use negative numbers to select IP address from the end (right side) of the list. Here are the recommended values:

| Offset | Description | |--------|-------------| | 0 | The default value. Allow the server to select the public IP automatically. | | -1 | Always select the last IP in the list (i.e. the TCP socket IP). Use this mode if your server is connected to the internet directly. | | -2 | Always select the second-to-last IP in the list. Use this mode if you have a single proxy device in front of your server (e.g. a load balancer). | | -3 | Always select the third-to-last IP in the list. Use this mode if you have two proxy devices in front of your server (e.g. a load balancer and CDN / cache). |

https

This boolean allows you to enable HTTPS (SSL) support in the web server. It defaults to false. Note that you must also set https_port, and possibly https_cert_file and https_key_file for this to work.

https_port

If HTTPS mode is enabled, this is the port to listen on for secure requests. The standard HTTPS port is 443.

https_alt_ports

If you would like to have the server listen on additional HTTPS ports, add them here as an array. Example:

{
	"https_port": 443,
	"https_alt_ports": [ 9000, 9001 ]
}

https_cert_file

If HTTPS mode is enabled, this should point to your SSL certificate file on disk. The certificate file typically has a .crt filename extension, or possibly cert.pem if using Let's Encrypt.

https_key_file

If HTTPS mode is enabled, this should point to your SSL private key file on disk. The key file typically has a .key filename extension, or possibly privkey.pem if using Let's Encrypt.

https_ca_file

If HTTPS mode is enabled, this should point to your SSL chain file on disk. This is optional, as some SSL certificates do not provide one. If using Let's Encrypt this file will be named chain.pem.

https_force

If HTTPS mode is enabled, you can set this param to boolean true to force all requests to be HTTPS. Meaning, if someone attempts a non-secure plain HTTP request to any URI, their client will be redirected to an equivalent HTTPS URI.

https_header_detect

Your network architecture may have a proxy server or load balancer sitting in front of the web server, and performing all HTTPS/SSL encryption for you. Usually, these devices inject some kind of HTTP request header into the back-end web server request, so you can "detect" a front-end HTTPS proxy request in your code. For example, Amazon AWS load balancers inject the following HTTP request header into all back-end requests:

X-Forwarded-Proto: https

The https_header_detect property allows you to define any number of header regular expression matches, that will "pseudo-enable" SSL mode in the web server. Meaning, the args.request.headers.ssl property will be set to true, and calls to server.getSelfURL() will have a https:// prefix. Here is an example configuration, which detects many commonly used headers:

{
	"https_header_detect": {
		"Front-End-Https": "^on$",
		"X-Url-Scheme": "^https$",
		"X-Forwarded-Protocol": "^https$",
		"X-Forwarded-Proto": "^https$",
		"X-Forwarded-Ssl": "^on$"
	}
}

Note that these are matched using logical OR, so only one of them needs to match to enable SSL mode. The values are interpreted as regular expressions, in case you need to match more than one header value.

https_timeout

This sets the idle socket timeout for all incoming HTTPS requests. If omitted, the Node.js default is 2 minutes. Please specify your value in seconds.

Custom URI Handlers

You can attach your own handler methods for intercepting and responding to certain incoming URIs. So for example, instead of the URI /api/add_user looking for a static file on disk, you can have the web server invoke your own function for handling it, and sending a custom response.

To do this, call the addURIHandler() method and pass in the URI string, a name (for logging), and a callback function:

server.WebServer.addURIHandler( '/my/custom/uri', 'Custom Name', function(args, callback) {
	// custom request handler for our URI
	callback( 
		"200 OK", 
		{ 'Content-Type': "text/html" }, 
		"Hello this is custom content!\n" 
	);
} );

URIs must match exactly (sans the query string), and the case is sensitive. If you need to implement something more complicated, such as a regular expression match, you can pass one of these in as well. Example:

server.WebServer.addURIHandler( /^\/custom\/match\/$/i, 'Custom2', function(args, callback) {...} );

Your handler function is passed exactly two arguments. First, an args object containing all kinds of useful information about the request (see args below), and a callback function that you must call when the request is complete and you want to send a response.

If you specified a regular expression with parenthesis groups for the URI, the matches array will be included in the args object as args.matches. Using this you can extract your matched groups from the URI, for e.g. /^\/api\/(\w+)/.

Note that by default, URIs are only matched on their path portion (i.e. sans query string). To include the query string in URI matches, set the http_full_uri_match configuration property to true.

Access Control Lists

If you want to restrict access to certain URI handlers, you can specify an ACL which represents a list of IP address ranges to allow. To use the default ACL, simply pass true as the 3rd argument to addURIHandler(), just before your callback. This flags the URI as private. Example:

server.WebServer.addURIHandler( /^\/private/, "Private Admin Area", true, function(args, callback) {
	// request allowed
	callback( "200 OK", { 'Content-Type': 'text/html' }, "<h1>Access granted!</h1>\n" );
} );

This will protect the handler using the default ACL, as specified by the http_default_acl configuration parameter. However, if you want to specify a custom ACL per handler, simply replace the true argument with an array of IPv4 and/or IPv6 addresses, partials or CIDR blocks. Example:

server.WebServer.addURIHandler( /^\/secret/, "Super Secret Area", ['10.0.0.0/8', 'fd00::/8'], function(args, callback) {
	// request allowed
	callback( "200 OK", { 'Content-Type': 'text/html' }, "<h1>Access granted!</h1>\n" );
} );

This would only allow requests from either 10.0.0.0/8 (IPv4) or fd00::/8 (IPv6).

The ACL code scans all the IP addresses from the client, including the socket IP and any passed as part of HTTP headers (populated by load balancers, proxies, etc.). See args.ips for more details on this. All the IPs must pass the ACL test in order for the request to be allowed through to your handler.

If a request is rejected, your handler isn't even called. Instead, a standard HTTP 403 Forbidden response is sent to the client, and an error is logged.

Internal File Redirects

To setup an internal file redirect, you can substitute the final callback function for a string, pointing to a fully-qualified filesystem path. The target file will be served up in place of the original URI. You can also combine this with an ACL for extra protection for private files. Example:

server.WebServer.addURIHandler( /^\/secret.txt$/, "Special Secrets", true, '/private/myapp/docs/secret.txt' );

Note that the Content-Type response header is automatically set based on the target file you are redirecting to.

Static Directory Handlers

If you would like to host static files in other places besides http_htdocs_dir, possibly with different options, then look no further than the addDirectoryHandler() method. This allows you to set up static file handling with a custom base URI, a custom base directory on disk, and apply other options as well. You can call this method as many times as you like to setup multiple static file directories. Example:

server.WebServer.addDirectoryHandler( /^\/mycustomdir/, '/let/www/custom' );

The above example would catch all incoming requests starting with /mycustomdir, and serve up static files inside of the /let/www/custom directory on disk (and possibly nested directories as well). So a URL such as http://MYSERVER/mycustomdir/foo/file1.txt would map to the file /let/www/custom/foo/file1.txt on disk.

In this case a default TTL is applied to all files via http_static_ttl. If you would like to customize the TTL for your custom static directory, as well as specify other options, pass in an object as the 3rd argument to addDirectoryHandler(). Example of this:

server.WebServer.addDirectoryHandler( /^\/mycustomdir/, '/let/www/custom', {
	acl: true
	ttl: 3600,
	headers: {
		'X-Custom': '12345'
	}
} );

In this example the files would be restricted to client IP addresses matching the http_default_acl, and would be served up with a custom TTL of 3600 seconds (specifically, the Cache-Control response header would be set to public, max-age=3600). Finally, all static file responses would include the X-Custom: 12345 header. Here is a list of the available properties in the options object:

| Property Name | Type | Description | |---------------|------|-------------| | acl | Boolean | Optionally restrict the static files to an IP-based ACL. You can set this to Boolean true to use the http_default_acl, or specify an array of IPv4 and/or IPv6 addresses, partials or CIDR blocks. | | ttl | Mixed | Optionally customize the TTL (Cache-Control header). Set this to a number to use the public, max-age=### format, or a string to specify the entire header value yourself. | | headers | Object | Optionally include additional HTTP headers with every static response. Note that you cannot use this to override built-in headers like Content-Type, Content-Length, ETag, and others. It can only be used to insert unique headers. |

Sending Responses

There are actually four different ways you can send an HTTP response. They are all detailed below:

Standard Response

The first type of response is shown above, and that is passing three arguments to the callback function. The HTTP response status line (e.g. 200 OK or 404 File Not Found), a response headers object containing key/value pairs for any custom headers you want to send back (will be combined with the default ones), and finally the content body. Example:

callback( 
	"200 OK", 
	{ 'Content-Type': "text/html" }, 
	"Hello this is custom content!\n" 
);

The content body can be a string, a Buffer object, or a readable stream.

Custom Response

The second type of response is to send content directly to the underlying Node.js server by yourself, using args.response (see below). If you do this, you can pass true to the callback function, indicating to the web server that you "handled" the response, and it shouldn't do anything else. Example:

server.WebServer.addURIHandler( '/my/custom/uri', 'Custom Name', function(args, callback) {
	// send custom raw response
	let response = args.response;
	response.writeHead( 200, "OK", { 'Content-Type': "text/html" } );
	response.write( "Hello this is custom content!\n" );
	response.end();
	
	// indicate we are done, and have handled things ourselves
	callback( true );
} );

JSON Response

The third way is to pass a single object to the callback function, which will be serialized to JSON and sent back as an AJAX style response to the client. Example:

server.WebServer.addURIHandler( '/my/custom/uri', 'Custom Name', function(args, callback) {
	// send custom JSON response
	callback( {
		Code: 0,
		Description: "Success",
		User: { Name: "Joe", Email: "[email protected]" }
	} );
} );

Typically this is sent as pure JSON with the Content-Type application/json. The raw HTTP response would look something like this:

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 79
Content-Type: application/json
Date: Sun, 05 Apr 2015 20:58:50 GMT
Server: Test 1.0

{"Code":0,"Description":"Success","User":{"Name":"Joe","Email":"[email protected]"}}

Now, depending on the request URL's query string, two variants of the JSON response are possible. First, if there is a callback query parameter present, it will be prefixed onto the front of the JSON payload, which will be wrapped in parenthesis, and Content-Type will be switched to text/javascript. This is an AJAX / JSONP style of response, and looks like this, assuming a request URL containing ?callback=myfunc:

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 88
Content-Type: text/javascript
Date: Sun, 05 Apr 2015 21:25:49 GMT
Server: Test 1.0

myfunc({"Code":0,"Description":"Success","User":{"Name":"Joe","Email":"[email protected]"}});

And finally, if the request URL's query string contains both a callback, and a format parameter set to html, the response will be actual HTML (Content-Type text/html) with a <script> tag embedded containing the JSON and callback wrapper. This is useful for IFRAMEs which may need to talk to their parent window after a form submission. Here is an example assuming a request URL containing ?callback=parent.myfunc&format=html:

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 151
Content-Type: text/html
Date: Sun, 05 Apr 2015 21:28:48 GMT
Server: Test 1.0

<html><head><script>parent.myfunc({"Code":0,"Description":"Success","User":{"Name":"Joe","Email":"[email protected]"}});
</script></head><body>&nbsp;</body></html>

Non-Response

The fourth and final type of response is a non-response, and this is achieved by passing false to the callback function. This indicates to the web server that your code did not handle the request, and it should fall back to looking up a static file on disk. Example:

server.WebServer.addURIHandler( '/my/custom/uri', 'Custom Name', function(args, callback) {
	// we did not handle the request, so tell the web server to do so
	callback( false );
} );

Note that there is currently no logic to fallback to other custom URI handlers. The only fallback logic, if a handler returns false, is to lookup a static file on disk.

To perform an internal file redirect from inside your URI handler code, set the internalFile property of the args object to your destination filesystem path, then pass false to the callback:

server.WebServer.addURIHandler( '/intredir', "Internal Redirect", true, function(args, callback) {
	// perform internal redirect to custom file
	args.internalFile = '/private/myapp/docs/secret.txt';
	callback(false);
} );

args

Your URI handler function is passed an args object containing the following properties:

args.request

This is a reference to the underlying Node.js server request object. From this you have access to things like:

| Property | Description | |----------|-------------| | request.httpVersion | The version of the HTTP protocol used in the request. | | request.headers | An object containing all the HTTP request headers (lower-cased). | | request.method | The HTTP method used in the request, e.g. GET, POST, etc. | | request.url | The complete URI of the request (sans protocol and hostname). | | request.socket | A reference to the underlying socket connection for the request. |

For more detailed documentation on the request object, see Node's http.IncomingMessage.

args.response

This is a reference to the underlying Node.js server response object. From this you have access to things like:

| Property / Method() | Description | |----------|-------------| | response.writeHead() | This writes the HTTP status code, message and headers to the socket. | | response.setTimeout() | This sets a timeout on the response. | | response.statusCode | This sets the HTTP status code, e.g. 200, 404, etc. | | response.statusMessage | This sets the HTTP status message, e.g. OK, File Not Found, etc. | | response.setHeader() | This sets a single header key / value pair in the response. | | response.write() | This writes a chunk of data to the socket. | | response.end() | This indicates that the response has been completely sent. |

For more detailed documentation on the response object, see Node's http.ServerResponse.

args.ip

This will be set to the user's remote IP address. Generally, it will be set to the first public IP address if multiple addresses are provided via proxy HTTP headers and the socket.

Meaning, if the user is sitting behind one or more proxy servers, or your web server is behind a load balancer, this will attempt to locate the user's true public (non-private) IP address. If none is found, it'll just return the first IP address, honoring proxy headers before the socket (which is usually correct).

See http_public_ip_offset for details on customizing the behavior of this property.

If you just want the socket IP by itself, you can get it from args.request.socket.remoteAddress.

args.ips

This will be set to an array of all the user's remote IP addresses, taking into account the socket IP and various HTTP headers populated by proxies and load balancers, if applicable. The header address(es) will come first, if applicable, followed by the socket IP at the end.

The following HTTP headers are scanned for IP addresses to build the args.ips array:

| Header | Syntax | Description | |--------|--------|-------------| | X-Forwarded-For | Comma-Separated | The de-facto standard header for identifying the originating IP address of a client connecting through an HTTP proxy or load balancer. See X-Forwarded-For. | | Forwarded-For | Comma-Separated | Alias for X-Forwarded-For. | | Forwarded | Custom | New standard header as defined in RFC 7239, with custom syntax. See Forwarded. | X-Forwarded | Custom | Alias for Forwarded. | | X-Client-IP | Single | Non-standard, used by Heroku, etc. | | CF-Connecting-IP | Single | Non-standard, used by CloudFlare. | | True-Client-IP | Single | Non-standard, used by Akamai, CloudFlare, etc. | | X-Real-IP | Single | Non-standard, used by Nginx, FCGI, etc. | | X-Cluster-Client-IP | Single | Non-standard, used by Rackspace, Riverbed, etc. |

args.query

This will be an object containing key/value pairs from the URL query string, if applicable, parsed via the Node.js core Query String module.

Duplicate query params become an array. For example, an incoming URI such as /something?foo=bar1&foo=bar2&name=joe would produce the following args.query object:

{
	"foo": ["bar1", "bar2"],
	"name": "joe"
}

See http_flatten_query if you would rather duplicate query parameters be flattened (latter prevails).

args.params

If the request was a HTTP POST, this will contain all the post parameters as key/value pairs. This will take one of three forms, depending on the request's Content-Type header:

Standard HTTP POST

If the request Content-Type was one of the standard application/x-www-form-urlencoded or multipart/form-data, all the key/value pairs from the post data will be parsed, and provided in the args.params object. We use the 3rd party Formidable module for this work.

JSON REST POST

If the request is a "pure" JSON POST, meaning the Content-Type contains json or javascript, the content body will be parsed as a single JSON string, and the result object placed into args.params.

Unknown POST

If the Content-Type doesn't match any of the above values, it will simply be treated as a plain binary data, and a Buffer will be placed into args.params.raw.

args.files

If the request was a HTTP POST and contained any file uploads, they will be accessible through this property. Files are saved to a temp directory and can be moved to a custom location, or loaded directly. They will be keyed by the POST parameter name, and the value will be an object containing the following properties:

| Property | Description | |----------|-------------| | size | The size of the uploaded file in bytes. | | path | The path to the temp file on disk containing the file contents. | | name | The filename of the file as provided by the client. | | type | The mime type of the file, according to the client. | | lastModifiedDate | A date object containing the last mod date of the file, if available. |

For more details, please see the documentation on the Formidable.File object.

All temp files are automatically deleted at the end of the request.

args.cookies

This is an object parsed from the incoming Cookie HTTP header, if present. The contents will be key/value pairs for each semicolon-separated cookie provided. For example, if the client sent in a session_id cookie, it could be accessed like this:

let session_id = args.cookies['session_id'];

args.perf

This is a reference to a pixl-perf object, which is used internally by the web server to track performance metrics for the request. The metrics may be logged at the end of each request (see Transaction Logging below) and included in the stats (see Stats below).

args.server

This is a reference to the pixl-server object which handled the request.

args.id

This is an internal ID string used by the server to track and log individual requests.

Request Filters

Filters allow you to preprocess a request, before any handlers get their hands on it. They can pass data through, manipulate it, or even interrupt and abort requests. Filters are attached to particular URIs or URI patterns, and multiple may be applied to one request, depending on your rules. They can be asynchronous, and can also pass data between one another if desired.

You can attach your own filter methods for intercepting and responding to certain incoming URIs. So for example, let's say we want to filter the URI /api/add_user before the handler gets it, and inject some custom data. To do this, call the addURIFilter() method and pass in the URI string, a name (for logging), and a callback function:

server.WebServer.addURIFilter( /.+/, "My Filter", function(args, callback) {
	// add a nugget into request query
	args.query.filter_nugget = 42;
	
	// add a custom response header too
	args.response.setHeader('X-Filtered', "4242");
	
	callback(false); // passthru
} );

So here we are injecting filter_nugget into the args.query object, which is preserved and passed down to other filters and handlers. Also, we are adding a X-Filtered header to the response (whoever ends up sending it). Finally, we call the callback function passing false, which means to pass the request through to other filters and/or handlers (see below for more on this).

URI strings must match exactly (sans the query string), and the case is sensitive. If you need to match something more complicated, such as a regular expression, you can pass one of these in place of the URI string. Example:

server.WebServer.addURIFilter( /^\/custom\/match\/$/i, 'Custom2', function(args, callback) {...} );

Your filter handler function is passed exactly two arguments. First, an args object containing all kinds of useful information about the request (see args above), and a callback function that you must invoke when the filter is complete, and you want to either allow the request to continue, or interrupt it and send your own response.

As shown above, passing false to the callback means to pass the request through to downstream filters and handlers. If you want to intercept and abort the request, and send your own response preventing any further processing, you can pass a Standard Response to the callback, i.e. send exactly 3 arguments, an HTTP response code, HTTP response headers, and the response body (or null):

server.WebServer.addURIFilter( /.+/, "Reject All", function(args, callback) {
	// intercept everything and send our own custom response
	callback(
		"418 I'm a teapot", 
		{ 'X-Filtered': 42 },
		null
	);
} );

This will intercept and abort all requests, sending back a HTTP 418 error.

To pass data between filters and potentially handlers, simply add properties into the args object. This object is preserved for the lifetime of the request, and the same object reference is passed to all filters and handlers. Just be careful of namespace collisions with existing properties in the object. See args above for details.

Transaction Logging

In addition to the standard debug logging in pixl-server, the web server component can also log each request as a transaction. This is an optional feature which is disabled by default. To enable it, set the http_log_requests configuration property to true. The pixl-server log will then include a transaction row for every completed web request. Example:

[1466210619.37][2016/06/17 17:43:39][joeretina.local][WebServer][transaction][HTTP 200 OK][/server-status?pretty=1][{"id":"r4","proto":"http","ips":["::ffff:127.0.0.1"],"host":"127.0.0.1:3012","ua":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/601.6.17 (KHTML, like Gecko) Version/9.1.1 Safari/601.6.17","perf":{"scale":1000,"perf":{"total":10.266,"read":0.256,"process":1.077,"write":7.198},"counters":{"bytes_in":587,"bytes_out":431,"num_requests":1}}}]

The log columns are configurable in pixl-server, but are typically the following:

| Column | Name | Description | |--------|------|-------------| | 1 | hires_epoch | Epoch date/time, including milliseconds (floating point). | | 2 | date | Human-readable date/time, in the local server timezone. | | 3 | hostname | The hostname of the server. | | 4 | component | The server component name (WebServer). | | 5 | category | The category of the log entry (transaction). | | 6 | code | The HTTP response code and message, e.g. HTTP 200 OK. | | 7 | msg | The URI of the request. | | 8 | data | A JSON document containing data about the request. |

The data column is a JSON document containing various bits of additional information about the request. Here is a formatted example:

{
	"id": "r4",
	"proto": "http",
	"ip": "::ffff:127.0.0.1",
	"ips": [
		"::ffff:127.0.0.1"
	],
	"port": 3012,
	"socket": "c13",
	"ua": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/601.6.17 (KHTML, like Gecko) Version/9.1.1 Safari/601.6.17",
	"host": "localhost",
	"perf": {
		"scale": 1000,
		"perf": {
			"total": 8.041,
			"read": 0.077,
			"process": 1.315,
			"write": 5.451
		},
		"counters": {
			"bytes_in": 587,
			"bytes_out": 639,
			"num_requests": 1
		}
	}
}

Here are descriptions of the data JSON properties:

| Property | Type | Description | |----------|------|-------------| | id | String | The internal ID for the request. | | method | String | The HTTP method for the request, e.g. GET, POST. | | proto | String | The protocol of the request (http or https). | | ip | String | The first non-internal IP address (see args.ip). | | ips | Array | All the client IPs as an array (includes those from proxy headers). | | port | Number | Which port number the request came in on. | | socket | String | The unique ID of the socket which served the request. | | ua | String | The User-Agent string from the request headers. | | host | String | The hostname from the request URL. | | perf | Object | Performance metrics, see below. |

The perf object contains performance metrics for the request, as returned from the pixl-perf module. It includes a scale property denoting that all the metrics are displayed in milliseconds (i.e. 1000). The metrics themselves are in the perf object, and counters such as the number of bytes in/out are in the counters object.

If you only want to log some requests, but not all of them, you can specify a regular expression in the http_regex_log configuration property, which is matched against the incoming request URIs. Example:

{
	"http_regex_log": "^/my/special/path"
}

Request Detail Logging

If you set both the http_log_requests and http_log_request_details configuration properties to true, pixl-server will include verbose details in the transaction logs, specifically in the JSON-formatted data column. It will include the raw request and raw response (if in text format), and extra details about both the request and the response. Example of the data column from the log, pretty-printed:

{
	"id": "r10",
	"method": "POST",
	"proto": "http",
	"ip": "::1",
	"ips": [
		"::1"
	],
	"port": 3012,
	"socket": "c8",
	"perf": {
		"scale": 1000,
		"perf": {
			"total": 22.689,
			"queue": 0.261,
			"read": 15.176,
			"process": 1.791,
			"encode": 1.281,
			"write": 1.159
		},
		"counters": {
			"bytes_in": 975133,
			"bytes_out": 413,
			"num_requests": 1
		}
	},
	"files": {
		"file1": {
			"path": "/var/folders/11/r_0sz6s13cx1jn68l4m90zfr0000gn/T/f92cd259263698f0e19581400.LBM",
			"type": "application/octet-stream",
			"name": "V04.LBM",
			"size": 318742,
			"mtime": "2024-03-18T20:45:01.328Z"
		}
	},
	"headers": {
		"host": "localhost:3012",
		"accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
		"sec-fetch-site": "same-origin",
		"accept-language": "en-US,en;q=0.9",
		"accept-encoding": "gzip, deflate",
		"sec-fetch-mode": "navigate",
		"content-type": "multipart/form-data; boundary=----WebKitFormBoundaryAzquNdwdvTjj9ArR",
		"origin": "http://localhost:3012",
		"user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Safari/605.1.15",
		"referer": "http://localhost:3012/upload.html",
		"upgrade-insecure-requests": "1",
		"content-length": "319132",
		"connection": "keep-alive",
		"sec-fetch-dest": "document"
	},
	"cookies": {},
	"query": {
		"pretty": "1"
	},
	"params": {
		"key1": "value1",
		"key2": "value2"
	},
	"response": {
		"code": 200,
		"status": "OK",
		"headers": {
			"content-type": "application/json",
			"x-joetest": "9876",
			"server": "Test Server 1.0",
			"content-length": "261",
			"content-encoding": "gzip"
		},
		"raw": "{\n\t\"code\": 0,\n\t\"query\": {\n\t\t\"pretty\": \"1\"\n\t},\n\t\"params\": {\n\t\t\"key1\": \"value1\",\n\t\t\"key2\": \"value2\"\n\t},\n\t\"cookies\": {},\n\t\"files\": {\n\t\t\"file1\": {\n\t\t\t\"path\": \"/var/folders/11/r_0sz6s13cx1jn68l4m90zfr0000gn/T/f92cd259263698f0e19581400.LBM\",\n\t\t\t\"type\": \"application/octet-stream\",\n\t\t\t\"name\": \"V04.LBM\",\n\t\t\t\"size\": 318742,\n\t\t\t\"mtime\": \"2024-03-18T20:45:01.328Z\"\n\t\t}\n\t}\n}\n"
	}
}

As you can see, in addition to all the information logged with http_log_requests, the data column now includes even more detail. Here is the full list of all JSON properties and their descriptions, logged with http_log_request_details enabled:

| Property | Type | Description | |----------|------|-------------| | id | String | The internal ID for the request. | | method | String | The HTTP method for the request, e.g. GET, POST. | | proto | String | The protocol of the request (http or https). | | ip | String | The first non-internal IP address (see args.ip). | | ips | Array | All the client IPs as an array (includes those from proxy headers). | | port | Number | Which port number the request came in on. | | socket | String | The unique ID of the socket which served the request. | | perf | Object | Performance metrics, in pixl-perf format. | | files | Object | If applicable, metadata about all file uploads (file names, sizes, types, and dates). | | headers | Object | All the HTTP request headers in key/value format (lower-cased keys). | | cookies | Object | Cookies from the request, parsed and in key/value form. | | query | Object | The query string from the request URL parsed into key/value pairs. | | params | Object | Key/value pairs from the request, i.e. parsed JSON or form POST data. | | params.raw | String | If applicable, the raw request body as a UTF-8 string (see below). | | response | Object | Details about the HTTP response sent to the client. | | response.code | Number | The HTTP response code (e.g. 200). | | response.status | String | The HTTP response status (e.g. OK). | | response.headers | Object | All the HTTP response headers sent to the client (lower-cased keys). | | response.raw | String | If applicable, the raw response body as a UTF-8 string (see below). |

The raw request and response content will only be logged in certain cases:

• If the request was a JSON POST, then the parsed JSON document will be in the params object.
• If the request was a non-JSON POST, but the content is recognized to be text, then the raw request body will be in params.raw as a UTF-8 string.
• If the request was a form post, then the key/value pairs will be in the params object.
• If the request contained file uploads, they will be summarized in the files object (see above for example).
• If the response is recognized as text, it will be included in response.raw as a UTF-8 string.
• If the response is non-text (binary), the raw content will not be logged.
• If the response is pre-compressed by application code, it will not be logged.
• If the response is a stream, it will not be logged.

Performance Threshold Logging

In addition to Transaction Logging, pixl-server-web can also log performance metrics for certain requests, if the total request elapsed time meets or exceeds a custom threshold. This allows you to log only "slow" requests, i.e. those possibly requiring investigation. This is an optional feature which is disabled by default. To enable it, set the http_log_perf configuration property to true, and then set the http_perf_threshold_ms property to the desired logging threshold in milliseconds. Example:

{
	"http_log_perf": true,
	"http_perf_threshold_ms": 100
}

This would log all requests that took 100ms or longer. Here is an example performance log row for such a request:

[1654144635.900786][2022-06-01 21:37:15][joemax.local][25638][WebServer][perf][200 OK][/sleep?ms=110][{"id":"r4","proto":"http","ips":["127.0.0.1"],"host":"localhost:3012","ua":"curl/7.79.1","perf":{"scale":1000,"perf":{"total":117.214,"queue":0.072,"read":0.018,"process":112.894,"write":3.467},"counters":{"bytes_in":90,"bytes_out":179,"num_requests":1}},"pending":0,"running":0,"sockets":1}]

The log columns are configurable in pixl-server, but are typically the following:

| Column | Name | Description | |--------|------|-------------| | 1 | hires_epoch | Epoch date/time, including milliseconds (floating point). This is retroactively adjusted to log the start of the request. | | 2 | date | Human-readable date/time, in the local server timezone. This is retroactively adjusted to log the start of the request. | | 3 | hostname | The hostname of the server. | | 4 | component | The server component name (WebServer). | | 5 | category | The category of the log entry (perf). | | 6 | code | The HTTP response code and message, e.g. 200 OK. | | 7 | msg | The URI of the request. | | 8 | data | A JSON document containing data about the request and performance metrics. |

The data column is a JSON document containing various bits of additional information about the request, including the performance metrics. Here is a formatted example:

{
	"id": "r4",
	"proto": "http",
	"ips": [
		"127.0.0.1"
	],
	"host": "localhost:3012",
	"ua": "curl/7.79.1",
	"perf": {
		"scale": 1000,
		"perf": {
			"total": 117.214,
			"queue": 0.072,
			"read": 0.018,
			"process": 112.894,
			"write": 3.467
		},
		"counters": {
			"bytes_in": 90,
			"bytes_out": 179,
			"num_requests": 1
		}
	},
	"pending": 0,
	"running": 0,
	"sockets": 1
}

Here are descriptions of the data JSON properties:

| Property | Description | |----------|-------------| | id | The internal ID for the request. | | proto | The protocol of the request (http or https). | | ips | All the client IPs as an array (includes those from proxy headers). | | ua | The User-Agent string from the request headers. | | host | The hostname from the request URL. | | perf | Performance metrics, see below. | | pending | The total number of pending requests in the queue, as captured at the start of the current request. | | running | The total number of running (active) requests being served, as captured at the start