# Developer guide

This guide helps you get started developing Grafana.

## Dependencies

Make sure you have the following dependencies installed before setting up your developer environment:

- [Git](https://git-scm.com/)
- [Go](https://golang.org/dl/) (see [go.mod](../go.mod#L3) for minimum required version)
- [Node.js (Long Term Support)](https://nodejs.org), with [corepack enabled](https://nodejs.org/api/corepack.html#enabling-the-feature). See [.nvmrc](../.nvmrc) for supported version. It's recommend you use a version manager such as [nvm](https://github.com/nvm-sh/nvm), [fnm](https://github.com/Schniz/fnm), or similar.
- GCC (required for Cgo dependencies)

### macOS

We recommend using [Homebrew](https://brew.sh/) for installing any missing dependencies:

```
brew install git
brew install go
brew install node@20
corepack enable
```

### Windows

If you are running Grafana on Windows 10, we recommend installing the Windows Subsystem for Linux (WSL). For installation instructions, refer to our [Grafana setup guide for Windows environment](https://grafana.com/blog/2021/03/03/how-to-set-up-a-grafana-development-environment-on-a-windows-pc-using-wsl/).

## Download Grafana

We recommend using the Git command-line interface to download the source code for the Grafana project:

1. Open a terminal and run `git clone https://github.com/grafana/grafana.git`. This command downloads Grafana to a new `grafana` directory in your current directory.
1. Open the `grafana` directory in your favorite code editor.

For alternative ways of cloning the Grafana repository, please refer to [GitHub's cloning a repository](https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/cloning-a-repository) documentation.

**Warning:** Do not use `go get` to download Grafana. Recent versions of Go have added behavior which isn't compatible with the way the Grafana repository is structured.

### Configure precommit hooks

We use pre-commit hooks (via [lefthook](https://github.com/evilmartians/lefthook)) to lint, fix, and format code as you commit your changes. Previously the Grafana repository automatically installed these hook when you did `yarn install`, but they are now opt in for all contributors

Install the lefthook precommit hooks with:

```sh
make lefthook-install
```

To remove precommit hooks, run

```sh
make lefthook-uninstall
```

> [!NOTE]
> Contributors working on the frontend are highly encouraged to install the precommit hooks, even if your IDE formats on save, so the `.betterer.results` file is kept up to sync.

## Build Grafana

Grafana consists of two components; the _frontend_, and the _backend_.

### Frontend

Before we can build the frontend assets, we need to install the dependencies:

```
yarn install --immutable
```

> Troubleshooting: if you get the error `The remote archive doesn't match the expected checksum` for a dependency pulled from a link (e.g. `"tether-drop": "https://github.com/torkelo/drop"`): this is a temporary mismatch. To work around it (while someone corrects the issue), you can prefix your `yarn install --immutable` command with [`YARN_CHECKSUM_BEHAVIOR=update`](https://yarnpkg.com/advanced/error-codes#yn0018---cache_checksum_mismatch)

After the command has finished, we can start building our source code:

```
yarn start
```

This command will generate sass theme files, build all external plugins, then build the frontend assets.
Once `yarn start` has built the assets, it will continue to do so whenever any of the files change. This means you don't have to manually build the assets every time you change the code.

> Troubleshooting: if your first build works, but after pulling updates you see unexpected errors in the "Type-checking in progress..." stage, these can be caused by the [tsbuildinfo cache supporting incremental builds](https://www.typescriptlang.org/tsconfig#incremental). You can `rm tsconfig.tsbuildinfo` and re-try.

Next, we'll build & run the web server that will serve the frontend assets we just built.

### Backend

Build and run the backend by running `make run` in the root directory of the repository. This command compiles the Go source code and starts a web server.

> Are you having problems with [too many open files](#troubleshooting)?

By default, you can access the web server at `http://localhost:3000/`.

Log in using the default credentials:

| username | password |
| -------- | -------- |
| `admin`  | `admin`  |

When you log in for the first time, Grafana asks you to change your password.

#### Building on Windows

The Grafana backend includes SQLite which requires GCC to compile. So in order to compile Grafana on Windows you need to install GCC. We recommend [TDM-GCC](http://tdm-gcc.tdragon.net/download). Eventually, if you use [Scoop](https://scoop.sh), you can install GCC through that.

You can build the back-end as follows:

1. Follow the [instructions](https://github.com/google/wire#installing) to install the Wire tool.
2. Generate code using Wire:

```
# Default Wire tool install path: $GOPATH/bin/wire.exe
<Wire tool install path> gen -tags oss ./pkg/server ./pkg/cmd/grafana-cli/runner
```

3. Build the Grafana binaries:

```
go run build.go build
```

The Grafana binaries will be in bin\\windows-amd64.
Alternately, if you wish to use the `make` command, install [Make for Windows](http://gnuwin32.sourceforge.net/packages/make.htm) and use it in a Unix shell (f.ex. Git Bash).

## Test Grafana

The test suite consists of three types of tests: _Frontend tests_, _backend tests_, and _end-to-end tests_.

### Run frontend tests

We use [jest](https://jestjs.io/) for our frontend tests. Run them using Yarn:

```
yarn test
```

### Run backend tests

If you're developing for the backend, run the tests with the standard Go tool:

```
go test -v ./pkg/...
```

#### On Windows

Running the backend tests on Windows currently needs some tweaking, so use the build.go script:

```
go run build.go test
```

### Run SQLLite, PostgreSQL and MySQL integration tests

By default, grafana runs SQLite, to run test with SQLite

```bash
go test -covermode=atomic -tags=integration ./pkg/...
```

To run PostgreSQL and MySQL integration tests locally, you need to start the docker blocks for MySQL and/or PostgreSQL test data sources by running `make devenv sources=mysql_tests,postgres_tests`. When your test data sources are running, you can execute integration tests by running:

```bash
make test-go-integration-mysql
```

and/or

```bash
make test-go-integration-postgres
```

### Run end-to-end tests

Grafana uses [Cypress](https://www.cypress.io/) to end-to-end test core features. Core plugins use [Playwright](https://playwright.dev/) to run automated end-to-end tests. You can find more information on how to add end-to-end tests to your core plugin [here](./style-guides/e2e-plugins.md)

#### Running Cypress tests

To run all tests in a headless Chromium browser.

```
yarn e2e
```

By default, the end-to-end tests start a Grafana instance listening on `localhost:3001`. To use a different URL, set the `BASE_URL` environment variable:

```
BASE_URL=http://localhost:3333 yarn e2e
```

To follow all tests in the browser while they're running, use `yarn e2e:debug`

```
yarn e2e:debug
```

To choose a single test to follow in the browser as it runs, use `yarn e2e:dev`

```
yarn e2e:dev
```

#### To run the Playwright tests:

**Note:** If you're using VS Code as your development editor, it's recommended to install the [Playwright test extension](https://marketplace.visualstudio.com/items?itemName=ms-playwright.playwright). It allows you to run, debug and generate Playwright tests from within the editor. For more information about the extension and how to install it, refer to the [Playwright documentation](https://playwright.dev/docs/getting-started-vscode).

Each version of Playwright needs specific versions of browser binaries to operate. You will need to use the Playwright CLI to install these browsers.

```
yarn playwright install chromium
```

To run all tests in a headless Chromium browser and display results in the terminal.

```
yarn e2e:playwright
```

For a better developer experience, open the Playwright UI where you can easily walk through each step of the test and visually see what was happening before, during and after each step.

```
yarn e2e:playwright:ui
```

To open the HTML reporter for the last test run session.

```
yarn e2e:playwright:report
```

## Configure Grafana for development

The default configuration, `defaults.ini`, is located in the `conf` directory.

To override the default configuration, create a `custom.ini` file in the `conf` directory. You only need to add the options you wish to override.

Enable the development mode, by adding the following line in your `custom.ini`:

```
app_mode = development
```

### Add data sources

By now, you should be able to build and test a change you've made to the Grafana source code. In most cases, you'll need to add at least one data source to verify the change.

To set up data sources for your development environment, go to the [devenv](/devenv) directory in the Grafana repository:

```
cd devenv
```

Run the `setup.sh` script to set up a set of data sources and dashboards in your local Grafana instance. The script creates a set of data sources called **gdev-\<type\>**, and a set of dashboards located in a folder called **gdev dashboards**.

Some of the data sources require databases to run in the background.

Installing and configuring databases can be a tricky business. Grafana uses [Docker](https://docker.com) to make the task of setting up databases a little easier. Make sure you [install Docker](https://docs.docker.com/docker-for-mac/install/) before proceeding to the next step.

In the root directory of your Grafana repository, run the following command:

```
make devenv sources=influxdb,loki
```

The script generates a Docker Compose file with the databases you specify as `sources`, and runs them in the background.

See the repository for all the [available data sources](/devenv/docker/blocks). Note that some data sources have specific Docker images for macOS, e.g. `nginx_proxy_mac`.

## Build a Docker image

To build a Docker image, run:

```
make build-docker-full
```

The resulting image will be tagged as grafana/grafana:dev.

**Note:** If you are using Docker for macOS, be sure to set the memory limit to be larger than 2 GiB. Otherwise, `grunt build` may fail. The memory limit settings are available under **Docker Desktop** -> **Preferences** -> **Advanced**.

## Troubleshooting

Are you having issues with setting up your environment? Here are some tips that might help.

### IDE configuration

Configure your IDE to use the Typescript version from the Grafana repository. The version should match the Typescript version in the package.json file, and is typically at the path `node_modules/.bin/tsc`.

Previously Grafana used Yarn PnP to install frontend dependencies, which required additional special IDE configuration. This is no longer the case. If you have custom paths in your IDE for ESLint, Prettier, or Typescript, you can now remove them and use the defaults from node_modules.

### Too many open files when running `make run`

Depending on your environment, you may have to increase the maximum number of open files allowed. For the rest of this section, we will assume you are on a Unix like OS (e.g. Linux/macOS), where you can control the maximum number of open files through the [ulimit](https://ss64.com/bash/ulimit.html) shell command.

To see how many open files are allowed, run:

```
ulimit -a
```

To change the number of open files allowed, run:

```
ulimit -S -n 4096
```

The number of files needed may be different on your environment. To determine the number of open files needed by `make run`, run:

```
find ./conf ./pkg ./public/views | wc -l
```

Another alternative is to limit the files being watched. The directories that are watched for changes are listed in the `.bra.toml` file in the root directory.

To retain your `ulimit` configuration, i.e. so it will be remembered for future sessions, you need to commit it to your command line shell initialization file. Which file this will be depends on the shell you are using, here are some examples:

- zsh -> ~/.zshrc
- bash -> ~/.bashrc

Commit your ulimit configuration to your shell initialization file as follows ($LIMIT being your chosen limit and $INIT_FILE being the initialization file for your shell):

```
echo ulimit -S -n $LIMIT >> $INIT_FILE
```

Your command shell should read the initialization file in question every time it gets started, and apply your `ulimit` command.

For some people, typically using the bash shell, ulimit fails with an error similar to the following:

```
ulimit: open files: cannot modify limit: Operation not permitted
```

If that happens to you, chances are you've already set a lower limit and your shell won't let you set a higher one. Try looking in your shell initialization files (~/.bashrc typically), if there's already an ulimit command that you can tweak.

## Next steps

- Read our [style guides](/contribute/style-guides).
- Learn how to [Create a pull request](/contribute/create-pull-request.md).
- Read about the [architecture](architecture).
- Read through the [backend documentation](/contribute/backend/README.md).