Before you begin, you might want to read [How to contribute to Grafana as a junior dev](https://medium.com/@ivanahuckova/how-to-contribute-to-grafana-as-junior-dev-c01fe3064502) by [Ivana Huckova](https://medium.com/@ivanahuckova).
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.
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.
The Grafana backend includes Sqlite3 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).
The end to end tests in Grafana use [Cypress](https://www.cypress.io/) to run automated scripts in a headless Chromium browser. Read more about our [e2e framework](/contribute/style-guides/e2e.md).
By now, you should be able to build and test a change you've made to the Grafana source code. In most cases, you need to add at least one data source to verify the change.
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. `prometheus_mac`.
The resulting image will be tagged as grafana/grafana:dev.
**Note:** If you've already set up a local development environment, and you're running a `linux/amd64` machine, you can speed up building the Docker image:
1. Build the frontend: `go run build.go build-frontend`.
1. Build the Docker image: `make build-docker-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**.
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.
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 initalization files (~/.bashrc typically), if there's already a ulimit command that you can tweak.
- Learn how to [Create a pull request](/contribute/create-pull-request.md).
- Read [How to contribute to Grafana as a junior dev](https://medium.com/@ivanahuckova/how-to-contribute-to-grafana-as-junior-dev-c01fe3064502) by [Ivana Huckova](https://medium.com/@ivanahuckova).
