# OpenTelemetry mysql Instrumentation for Node.js

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

This module provides automatic instrumentation for the [`mysql2`](https://github.com/sidorares/node-mysql2) module, which may be loaded using the [`@opentelemetry/sdk-trace-node`](https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-sdk-trace-node) package and is included in the [`@opentelemetry/auto-instrumentations-node`](https://www.npmjs.com/package/@opentelemetry/auto-instrumentations-node) bundle.

If total installation size is not constrained, it is recommended to use the [`@opentelemetry/auto-instrumentations-node`](https://www.npmjs.com/package/@opentelemetry/auto-instrumentations-node) bundle with [@opentelemetry/sdk-node](`https://www.npmjs.com/package/@opentelemetry/sdk-node`) for the most seamless instrumentation experience.

Compatible with OpenTelemetry JS API and SDK `1.0+`.

## Installation

```bash
npm install --save @opentelemetry/instrumentation-mysql2
```

## Supported Versions

- [`mysql2`](https://www.npmjs.com/package/mysql2) versions `>=1.4.2 <4`

## Usage

OpenTelemetry MySQL2 Instrumentation allows the user to automatically collect trace data and export them to the backend of choice, to give observability to distributed systems when working with [mysql2](https://github.com/sidorares/node-mysql2).

To load a specific plugin (**MySQL2** in this case), specify it in the registerInstrumentations's configuration

```js
const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');
const { MySQL2Instrumentation } = require('@opentelemetry/instrumentation-mysql2');
const { registerInstrumentations } = require('@opentelemetry/instrumentation');

const provider = new NodeTracerProvider();
provider.register();

registerInstrumentations({
  instrumentations: [
    new MySQL2Instrumentation(),
  ],
})
```

### MySQL2 Instrumentation Options

You can set the following instrumentation options:

| Options                           | Type                                                    | Description                                                                                                                                                                                                                                                                                                                  |
|-----------------------------------|---------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `responseHook`                    | `MySQL2InstrumentationExecutionResponseHook` (function) | Function for adding custom attributes from db response                                                                                                                                                                                                                                                                       |
| `addSqlCommenterCommentToQueries` | `boolean`                                               | If true, adds [sqlcommenter](https://github.com/open-telemetry/opentelemetry-sqlcommenter) specification compliant comment to queries with tracing context (default false). _NOTE: A comment will not be added to queries that already contain `--` or `/* ... */` in them, even if these are not actually part of comments_ |
| `maskStatement`                   | `boolean`                                               | If true, masks the `db.statement` attribute in spans (default false) with the `maskStatementHook`                                                                                                                                                                                                                            |
| `maskStatementHook`               | `MySQL2InstrumentationMaskStatementHook` (function)     | Function for masking the `db.statement` attribute in spans  Default: `return query.replace(/\b\d+\b/g, '?').replac(/(["'])(?:(?=(\\?))\2.)*?\1/g, '?');`                                                                                                                                                                     |


## Semantic Conventions

This instrumentation implements Semantic Conventions (semconv) v1.7.0. Since then, networking (in semconv v1.23.1) and database (in semconv v1.33.0) semantic conventions were stabilized. As of `@opentelemetry/instrumentation-mysql2@0.53.0` support has been added for migrating to the stable semantic conventions using the `OTEL_SEMCONV_STABILITY_OPT_IN` environment variable as follows:

1. Upgrade to the latest version of this instrumentation package.
2. Set `OTEL_SEMCONV_STABILITY_OPT_IN=http/dup,database/dup` to emit both old and stable semantic conventions. (The `http` token is used to control the `net.*` attributes, the `database` token to control to `db.*` attributes.)
3. Modify alerts, dashboards, metrics, and other processes in your Observability system to use the stable semantic conventions.
4. Set `OTEL_SEMCONV_STABILITY_OPT_IN=http,database` to emit only the stable semantic conventions.

By default, if `OTEL_SEMCONV_STABILITY_OPT_IN` includes neither of the above tokens, the old v1.7.0 semconv is used.
The intent is to provide an approximate 6 month time window for users of this instrumentation to migrate to the new database and networking semconv, after which a new minor version will use the new semconv by default and drop support for the old semconv.
See [the HTTP migration guide](https://opentelemetry.io/docs/specs/semconv/non-normative/http-migration/) and the [database migration guide](https://opentelemetry.io/docs/specs/semconv/non-normative/db-migration/) for details.

Attributes collected:

| Old semconv            | Stable semconv                                  | Description                                                                   |
|------------------------|-------------------------------------------------|-------------------------------------------------------------------------------|
| `db.connection_string` | Removed                                         | The connection string used to connect to the database.                        |
| `db.name`              | Removed, integrated into the new `db.namespace` | The name of the database.                                                     |
| `db.system`            | `db.system.name`                                | 'mysql'                                                                       |
| `db.statement`         | `db.query.text`                                 | The database query being executed.                                            |
| `db.user`              | Removed                                         | User used to connect to the database.                                         |
| (not included)         | `db.namespace`                                  | The name of the database, fully qualified within the server address and port. |
| `net.peer.port`        | `server.port`                                   | Remote port number.                                                           |
| `net.peer.name`        | `server.address`                                | Remote hostname or similar.                                                   |


## 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][discussions-url]

## License

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

[discussions-url]: https://github.com/open-telemetry/opentelemetry-js/discussions
[license-url]: https://github.com/open-telemetry/opentelemetry-js-contrib/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-mysql2
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Finstrumentation-mysql2.svg