# Contributing to the APM Agent

The APM Agent is open source and we love to receive contributions from our community — you!

There are many ways to contribute,
from writing tutorials or blog posts,
improving the documentation,
submitting bug reports and feature requests or writing code.

You can get in touch with us through [Discuss](https://discuss.elastic.co/c/apm),
feedback and ideas are always welcome.

## Code contributions

If you have a bugfix or new feature that you would like to contribute,
please find or open an issue about it first.
Talk about what you would like to do.
It may be that somebody is already working on it,
or that there are particular issues that you should know about before implementing the change.

### Submitting your changes

Generally, we require that you test any code you are adding or modifying.
Once your changes are ready to submit for review:

1. Sign the Contributor License Agreement

   Please make sure you have signed our [Contributor License Agreement](https://www.elastic.co/contributor-agreement/).
   We are not asking you to assign copyright to us,
   but to give us the right to distribute your code without restriction.
   We ask this of all contributors in order to assure our users of the origin and continuing existence of the code.
   You only need to sign the CLA once.

2. Test your changes

   Run the test suite to make sure that nothing is broken.
   See [testing](#testing) for details.

3. Rebase your changes

   Update your local repository with the most recent code from the main repo,
   and rebase your branch on top of the latest main branch.
   We prefer your initial changes to be squashed into a single commit.
   Later,
   if we ask you to make changes,
   add them as separate commits.
   This makes them easier to review.
   As a final step before merging we will either ask you to squash all commits yourself or we'll do it for you.
   Don't forget to correctly format your commit messages.
   We follow [conventional commits](https://www.conventionalcommits.org/en/v1.0.0-beta.3/).

4. Submit a pull request

   Push your local changes to your forked copy of the repository and [submit a pull request](https://help.github.com/articles/using-pull-requests).
   In the pull request,
   choose a title which sums up the changes that you have made,
   and in the body provide more details about what your changes do.
   Also mention the number of the issue where discussion has taken place,
   eg "Closes #123".

5. Be patient

   We might not be able to review your code as fast as we would like to,
   but we'll do our best to dedicate it the attention it deserves.
   Your effort is much appreciated!

### Workflow

All feature development and most bug fixes hit the main branch first.
Pull requests should be reviewed by someone with commit access.
Once approved, the author of the pull request,
or reviewer if the author does not have commit access,
should "Squash and merge".

### Developing

The project structure follows a monorepo approach, all officially maintained modules are in the same repo. We use [Lerna](https://github.com/lerna/lerna) to achieve the same.

```sh
$ git clone git@github.com:elastic/apm-agent-rum-js.git && cd apm-agent-rum-js
$ npx lerna bootstrap
```

### Testing

Tests fall under unit, integration and end-to-end tests. Before running the test, we have to start the APM server manually since all the APM payload data are sent to the server.

```sh
NODEJS_VERSION=<nodeVersion> STACK_VERSION=<version> docker compose -f ./dev-utils/docker-compose.yml up -d fleet-server
# nodeVersion - corresponds to NodeJS version to be used when building the test images
# version - corresponds to Elastic Stack versions
```

Once the APM server is up and running, we can start running the tests. To run all the tests in each package

```sh
$ APM_SERVER_URL=<server-url> npm run test
```

To run all the tests on individual package set the `SCOPE` environment variable and start the tests

```sh
$ APM_SERVER_URL=<server-url> SCOPE=@elastic/apm-rum npm run test
```

##### Unit tests
```sh
$ npx lerna run --scope @elastic/apm-rum test:unit

// to run tests in watch mode

$ npx lerna run --scope @elastic/apm-rum karma:dev -- --grep <path-to-test-file>
```

##### Integration tests
```sh
$ npx lerna run --scope @elastic/apm-rum test:integration
```

### Linting

We use [prettier](https://github.com/prettier/prettier) for formatting code and [eslint](https://github.com/eslint/eslint) for other linting.

We use a git pre-commit hook to fix formatting and other auto-fixable eslint errors. Installing dependencies ensures this is enabled and should be run before the first commit.

```
$ npm install
```

To view the output of the linters.

```
$ npm run lint
```

### Releasing

See [RELEASE.md](RELEASE.md) for details on releasing.