Sarv: another static file server with brotli support

Presentation

Sarv is a new static file server which was developped to serve SPA (single page applications) with compressed files (brotli or gzip). There isn't compression during the request so files should be compressed before server start.

for performance improvements, sarv check files on start (technique inspired by sirv), this can lead to those errors:

• if a file is deleted, request will send a 500 error instead of a 404
• if a file is created, request will send a 404 error instead of a 200 with file

Motivation

The main goal of this project is creating a static file server able to serve brotli compressed files. According to this article of web.dev we can easly add brotli support on express static server. Then I discover sirv which seems to be a faster alternative (because it doesn't check file existance on every request). So I tried to use the same technique explained in web.dev article by using polka and sirv, but I've got some issues:

• content-type is set by sirv depending on file name. So by replacing path app.js by app.js.br, content-type become text/html instead of application/javascript. Even if we can set content-type header in a middleware or in setHeaders option, content-type is overwrite just before sending requested file.
• sirv has an option to send etag header for browser cache but it doesn’t check if-none-match request header to send a 304 response without the file.

So I create sarv, another static file server to workaround those issues. It's based on polka and most of the code is inspired by sirv but there are some differences:

• send pre-compressed brolti or gzip files (depending on accept-encoding header)
• force by default the browser to check if file hasn't change before getting it from cache (by using cache-control and etag headers)
• send 304 response without file if the browser has already load the file
• add some info in log (content-encoding and content-length)

Instalation

# install locally in your project
yarn add @epimodev/sarv
# install globally
yarn global add @epimodev/sarv

# or with npm
npm install @epimodev/sarv
# install globally
npm install --global @epimodev/sarv

Usage

# start a server for `public` folder
sarv public

# start a server binded to 8080 port
sarv public --port 8080

# start a server which fallback not found to index.html (for single page application)
sarv public --fallback /index.html

# display all options
sarv --help

Options

Description
  Run a static file server

Usage
  $ sarv [dir] [options]

Options
  -h, --host        Hostname to bind  (default localhost)
  -p, --port        Port to bind  (default 3000)
  -i, --index       Define index file name  (default index.html)
  -f, --fallback    Define fallback file
  -m, --maxage      Define max-age value (in sec) in "Cache-Control" header  (default 1209600)
  -v, --verbose     Display content encoding and content length in logs
  -v, --version     Displays current version
  -h, --help        Displays this message

Examples
  $ sarv public
  $ sarv public --port 8080
  $ sarv public --fallback /index.html