@nifty-lil-tricks/monitoring
v0.3.1
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A selection of useful utilities (or nifty li'l tricks!) for all things monitoring and OpenTelemetry
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@nifty-lil-tricks/monitoring
Note: This is an experimental package under active development. New releases may include breaking changes.
A selection of useful utilities (or nifty li'l tricks!) for all things monitoring and OpenTelemetry.
Table of contents
Installation
Note: this package works with TypeScript v5 or later
npm install @nifty-lil-tricks/monitoringExperimental stage 2 decorators
If you are using experimental stage 2 decorators, you will need to set the
following in your tsconfig.json:
{
"compilerOptions": {
"experimentalDecorators": true,
"emitDecoratorMetadata": true
}
}Stage 3 decorators
No setup is required.
Features
The following features are supported
- Monitoring decorator that wraps all methods of a class in an OpenTelemetry Span automatically tracing every method on the class.
Monitoring Decorator
- @nifty-lil-tricks/monitoring
- Table of contents
- Installation
- Features
- API
- Examples
- Support
- Useful links
- License
- Contributions
Monitoring Decorator Overview
This decorator wraps all methods of a class in an OpenTelemetry Span. If a parent span cannot be retrieved from the context of the method call, it will not be monitored.
The decorator will not affect any of the underlying functionality and it will also handle any legitimate errors thrown from the underlying method as appropriate.
Exported span for method that passes
A method of name hello on class Service that returns without error will
export the following span details by default:
{
"id": "b98126c289c5c9dc",
"name": "Service.hello",
"traceId": "a7b41739082880c506d62152de2e13a1",
"parentId": "f64d1571cd4a88dd",
"kind": 0,
"attributes": {
"monitoring.method": "hello",
"monitoring.class": "Service"
},
"status": { "code": 1 },
"timestamp": 1684136794317000,
"duration": 2010408,
"events": [],
"links": []
}Exported span for method that throws
A method of name hello on class Service that throws an error will export the
following span details by default:
{
"id": "7c5f84a384af9a63",
"name": "Service.hello",
"traceId": "931ba33b4ab375ade4f26c7ac93df4ce",
"parentId": "0182507d0f5f0a85",
"kind": 0,
"attributes": {
"monitoring.method": "hello",
"monitoring.class": "Service"
},
"status": { "code": 2, "message": "Error: something bad happened" },
"timestamp": 1684136986170000,
"duration": 502605,
"events": [],
"links": []
}Pre-requisites
Ensure OpenTelemetry tracing is set-up by ensuring:
- The provider is registered
- The monitored method is wrapped in the context of a parent span
- A global context manager is set up
See example set up for a quick guide to getting the above setup.
Wrap all methods of a class in a span
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor()
class Service {
async hello(): Promise<void> {
// Do work
await promisify(setTimeout)(500);
// Do nested work
await this.nested();
}
async nested(): Promise<void> {
// Do work
await promisify(setTimeout)(1000);
}
}Filter allowed methods to monitor
By default, the monitor decorator monitors all
non-private
methods. One can provide an allowedMethods option to filter the methods that
are monitored. This filter can be provided in several types:
string[]RegExp(methodName: string) => boolean
Filtering monitored methods by list of strings
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ allowedMethods: ["allowed1", "allowed2"] })
class Service {
// Not monitored
notAllowed(): void {}
// Monitored
allowed1(): void {}
// Monitored
allowed2(): void {}
}Filtering monitored methods by regex
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ allowedMethods: /^allowed.+/ })
class Service {
// Not monitored
notAllowed(): void {}
// Monitored
allowed1(): void {}
// Monitored
allowed2(): void {}
}Filtering monitored methods by function
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ allowedMethods: (method) => method.startsWith("allowed") })
class Service {
// Not monitored
notAllowed(): void {}
// Monitored
allowed1(): void {}
// Monitored
allowed2(): void {}
}Override the default Span kind
By default, the monitor decorator sets the Span Kind to be INTERNAL. This
option allows one to override this.
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ spanKind: SpanKind.SERVER })
class Service {
async hello(): Promise<void> {
// Do work
await promisify(setTimeout)(500);
}
}Override the inferred class name
By default, the monitor decorator infers the class name from the class. This option allows one to override this behaviour. A use-case for this would be when one has multiple classes of the same name defined.
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ className: "OtherService" })
class Service {
async hello(): Promise<void> {
// Do work
await promisify(setTimeout)(500);
}
}Override the default tracer name
By default, the monitor decorator uses the default tracer to record spans. This option allows one to override this behaviour.
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ tracerName: "some-other-tracer" })
class Service {
async hello(): Promise<void> {
// Do work
await promisify(setTimeout)(500);
}
}Caveats
Private methods as defined here are not monitoring by this decorator.
import { Monitor } from "@nifty-lil-tricks/monitoring";
import { promisify } from "node:util";
@Monitor({ tracerName: "some-other-tracer" })
class Service {
// Monitored
async hello(): Promise<void> {
// Not monitored
await this.#privateMethod(())
}
async #privateMethod(): Promise<void> {
// Do work
await promisify(setTimeout)(500);
}
}API
The API docs can be found here
Examples
Examples can be found here.
Basic example
To run the examples/basic.ts example, run the following:
- Ensure Docker is running
- Start the Jaeger collector:
npm run start:collector - Run the example:
npm run example:basic - Navigate to the Jaeger UI: http://localhost:16686
Nestjs example
To run the examples/basic.ts example, run the following:
- Ensure Docker is running
- Start the Jaeger collector:
npm run start:collector - Run the example:
npm run example:nestjs - Make a request to the app:
curl http://localhost:3000/ - Navigate to the Jaeger UI: http://localhost:16686
Support
| Platform Version | Supported | Notes |
| ---------------- | ------------------ | --------------------------------------------------------- |
| Node.JS v18 | :white_check_mark: | TypeScript v5+ for typings |
| Node.JS v20 | :white_check_mark: | TypeScript v5+ for typings |
| Deno v1 | :x: | Will be supported when OpenTelemetry is supported in Deno |
| Web Browsers | :x: | Coming soon |
Useful links
- For more information on OpenTelemetry, visit: https://opentelemetry.io/
- For more about OpenTelemetry JavaScript: https://github.com/open-telemetry/opentelemetry-js
- For help or feedback on this project, join us in GitHub Discussions
License
Nifty li'l tricks packages are 100% free and open-source, under the MIT license.
This package is Treeware. If you use it in production, then we ask that you buy the world a tree to thank us for our work. By contributing to the Treeware forest you’ll be creating employment for local families and restoring wildlife habitats.
Contributions
Contributions, issues and feature requests are very welcome. If you are using this package and fixed a bug for yourself, please consider submitting a PR!