# OpenTelemetry Instrumentation for web and node

[![NPM Published Version][npm-img]][npm-url]
[![Apache License][license-image]][license-image]

## Installation

```bash
npm install --save @opentelemetry/instrumentation
```

## Usage in Node

```typescript
import {
  InstrumentationBase,
  InstrumentationConfig,
  InstrumentationNodeModuleDefinition,
  InstrumentationNodeModuleFile,
} from '@opentelemetry/instrumentation';

import type * as module_name_to_be_patched from 'module_name_to_be_patched';

export class MyPlugin extends InstrumentationBase {
  constructor(config: InstrumentationConfig = {}) {
    super('MyPlugin', VERSION, config);
  }

  /**
   * Init method will be called when the plugin is constructed.
   * It returns an `InstrumentationNodeModuleDefinition` which describes
   *   the node module to be instrumented and patched.
   * It may also return a list of `InstrumentationNodeModuleDefinition`s if
   *   the plugin should patch multiple modules or versions.
   */
  protected init() {
    const module = new InstrumentationNodeModuleDefinition<typeof module_name_to_be_patched>(
      'module_name_to_be_patched',
      ['1.*'],
       this._onPatchMain,
       this._onUnPatchMain,
    );
    // in case you need to patch additional files - this is optional
    module.files.push(this._addPatchingMethod());

    return module;
    // you can also define more modules then just return an array of modules
    // return [module1, module2, ....]
  }

  private _onPatchMain(moduleExports: typeof module_name_to_be_patched) {
    this._wrap(
      moduleExports,
      'mainMethodName',
      this._patchMainMethodName()
    );
    return moduleExports;
  }

  private _onUnPatchMain(moduleExports: typeof module_name_to_be_patched) {
    this._unwrap(moduleExports, 'mainMethodName');
  }

  private _addPatchingMethod(): InstrumentationNodeModuleFile<typeof module_name_to_be_patched> {
    const file = new InstrumentationNodeModuleFile<typeof module_name_to_be_patched>(
      'module_name_to_be_patched/src/some_file.js',
      this._onPatchMethodName,
      this._onUnPatchMethodName,
    );
    return file;
  }

  private _onPatchMethodName(moduleExports: typeof module_name_to_be_patched) {
    this._wrap(
      moduleExports,
      'methodName',
      this._patchMethodName()
    );
    return moduleExports;
  }

  private _onUnPatchMethodName(moduleExports: typeof module_name_to_be_patched) {
    this._unwrap(moduleExports, 'methodName');
  }

  private _patchMethodName(): (original) => any {
    const plugin = this;
    return function methodName(original) {
      return function patchMethodName(this: any): PromiseOrValue<module_name_to_be_patched.methodName> {
        console.log('methodName', arguments);
        return original.apply(this, arguments);
      };
    };
  }

  private _patchMainMethodName(): (original) => any {
    const plugin = this;
    return function mainMethodName(original) {
      return function patchMainMethodName(this: any): PromiseOrValue<module_name_to_be_patched.mainMethodName> {
        console.log('mainMethodName', arguments);
        return original.apply(this, arguments);
      };
    };
  }
}

// Later

const myPLugin = new MyPlugin();
myPLugin.setTracerProvider(provider); // this is optional, only if global TracerProvider shouldn't be used
myPLugin.setMeterProvider(meterProvider); // this is optional
myPLugin.enable();
// or use Auto Loader
```

## Usage in Web

```typescript
import {
  InstrumentationBase,
  InstrumentationConfig,
} from '@opentelemetry/instrumentation';

import { Instrumentation } from '@opentelemetry/instrumentation';

export class MyPlugin extends InstrumentationBase {
  constructor(config: InstrumentationConfig = {}) {
    super('MyPlugin', VERSION, config);
  }

  private _patchOpen() {
    return (original: OpenFunction): OpenFunction => {
      const plugin = this;
      return function patchOpen(this: XMLHttpRequest, ...args): void {
        console.log('open', arguments);
        return original.apply(this, args);
      };
    };
  }

  public enable() {
    this._wrap(XMLHttpRequest.prototype, 'open', this._patchOpen());
  }
  public disable() {
    this._unwrap(XMLHttpRequest.prototype, 'open');
  }
}

// Later

const myPLugin = new MyPlugin();
myPLugin.setTracerProvider(provider); // this is optional, only if global TracerProvider shouldn't be used
myPLugin.setMeterProvider(meterProvider); // this is optional, only if global MeterProvider shouldn't be used
myPLugin.enable();
// or use Auto Loader
```

## AutoLoader

Successor of loading plugins through TracerProvider "plugins" option.
It also supersedes PluginLoader for node. The old configurations usually looks like

### NODE - old way using TracerProvider - not available anymore

```javascript
const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');
const { B3Propagator } = require('@opentelemetry/propagator-b3');
const provider = new NodeTracerProvider({
  plugins: {
    http: { enabled: false },
  },
});
provider.register({
  propagator: new B3Propagator(),
});
```

### WEB - old way using TracerProvider - not available anymore

```javascript
const { WebTracerProvider } = require('@opentelemetry/sdk-trace-web');
const { UserInteractionPlugin } = require('@opentelemetry/plugin-user-interaction');
const { XMLHttpRequestInstrumentation } = require('@opentelemetry/instrumentation-xml-http-request');
const { B3Propagator } = require('@opentelemetry/propagator-b3');
const provider = new WebTracerProvider({
  plugins: [
    new UserInteractionPlugin(),
    new XMLHttpRequestInstrumentation({
      ignoreUrls: [/localhost/],
      propagateTraceHeaderCorsUrls: [
        'http://localhost:8090',
      ],
    }),
  ],
});
provider.register({
  propagator: new B3Propagator(),
});
```

After change it will look like this - mixing plugins and instrumentations together
All plugins will be bound to TracerProvider as well as instrumentations

### NODE - Auto Loader

```javascript
const { B3Propagator } = require('@opentelemetry/propagator-b3');
const { registerInstrumentations } = require('@opentelemetry/instrumentation');
const { HttpInstrumentation } = require('@opentelemetry/instrumentation-http');
const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');

const tracerProvider = new NodeTracerProvider();

tracerProvider.register({
  propagator: new B3Propagator(),
});

registerInstrumentations({
  instrumentations: [
    new HttpInstrumentation(),
  ],
  //tracerProvider: tracerProvider, // optional, only if global TracerProvider shouldn't be used
  //meterProvider: meterProvider, // optional, only if global MeterProvider shouldn't be used
});

```

### WEB - Auto Loader

```javascript
const { B3Propagator } = require('@opentelemetry/propagator-b3');
const { registerInstrumentations } = require('@opentelemetry/instrumentation');
const { XMLHttpRequestInstrumentation } = require('@opentelemetry/instrumentation-xml-http-request');
const { WebTracerProvider } = require('@opentelemetry/sdk-trace-web');

const tracerProvider = new WebTracerProvider();

tracerProvider.register({
  propagator: new B3Propagator(),
});

registerInstrumentations({
  instrumentations: [
    new XMLHttpRequestInstrumentation({
      ignoreUrls: [/localhost/],
      propagateTraceHeaderCorsUrls: [
        'http://localhost:8090',
      ],
    }),
  ],
  //tracerProvider: tracerProvider, // optional, only if global TracerProvider shouldn't be used
  //meterProvider: meterProvider, // optional, only if global MeterProvider shouldn't be used
});
```

## Selection of the used TracerProvider/MeterProvider

The `registerInstrumentations()` API allows to specify which `TracerProvider` and/or `MeterProvider` to use by the given options object.
If nothing is specified the global registered provider is used. Usually this is what most users want therefore it's recommended to keep this default.

There might be usecase where someone has the need for more providers within an application. Please note that special care must be takes in such setups
to avoid leaking information from one provider to the other because there are a lot places where e.g. the global `ContextManager` or `Propagator` is used.

## License

Apache 2.0 - See [LICENSE][license-url] for more information.

## Useful links

- For more information on OpenTelemetry, visit: <https://opentelemetry.io/>
- For help or feedback on this project, join us in [GitHub Discussions][discussions-url]

[discussions-url]: https://github.com/open-telemetry/opentelemetry-js/discussions
[license-url]: https://github.com/open-telemetry/opentelemetry-js/blob/main/LICENSE
[license-image]: https://img.shields.io/badge/license-Apache_2.0-green.svg?style=flat
[npm-url]: https://www.npmjs.com/package/@opentelemetry/instrumentation
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Finstrumentation.svg
