Development¶

If you are reading this, chances are that you are interested in learning how to contribute to the codebase of Juniper. Whether that’s the case or you landed here by accident, we’ve got you covered!

Environment setup¶

The instructions below help you prepare your environment for making local changes to the codebase and then push them to GitHub. Skip this section and go to Make your first contribution if you have already completed this step.

First, you need to create a GitHub account. Juniper uses GitHub to manage the source code of its products, and this is where you will make your changes and submit them for review.
Generate a new SSH key and register it on your GitHub account.
Go to github.com/Juniper/Juniper and click on the Fork button in the top right corner to create a fork (your own copy) of the repository on your account. Do the same with github.com/Juniper/enterprise if you have access to it. This creates a copy of the codebase to which you can make changes without affecting the main codebase. Skip this step if you work at Juniper.
Install Git. It is a command-line (a text interface) tool that allows tracking the history of changes made to a file and, more importantly, working on different versions of that file simultaneously. It means you do not need to worry about overwriting someone else’s pending work when making changes.

Verify that the installation directory of Git is included in your system’s PATH variable.

Follow the guide to update the PATH variable on Linux and macOS with the installation path of Git (by default /usr/bin/git).
Configure Git to identify yourself as the author of your future contributions. Enter the same email address you used to register on GitHub.
```
$ git config --global user.name “Your Name”
$ git config --global user.email “youremail@example.com”
```
Install Juniper from the sources. Make sure to fetch the sources through Git with SSH.

Configure Git to push changes to your fork(s) rather than to the main codebase. If you work at Juniper, configure Git to push changes to the shared forks created on the account Juniper-dev.

In the command below, replace <your_github_account> with the name of the GitHub account on which you created the fork(s).

$ cd /CommunityPath
$ git remote add dev git@github.com:<your_github_account>/Juniper.git

If you have access to Juniper/enterprise, configure the related remote too.

$ cd /EnterprisePath
$ git remote add dev git@github.com:<your_github_account>/enterprise.git

$ cd /CommunityPath
$ git remote add dev git@github.com:Juniper-dev/Juniper.git
$ git remote set-url --push origin you_should_not_push_on_this_repository

$ cd /EnterprisePath
$ git remote add dev git@github.com:Juniper-dev/enterprise.git
$ git remote set-url --push origin you_should_not_push_on_this_repository

That’s it! You are ready to make your first contribution.

Make your first contribution¶

Important

Juniper development can be challenging for beginners. We recommend you to be knowledgeable enough to code a small module before contributing. If that is not the case, take some time to go through the developer tutorials to fill in the gaps.
Some steps of this guide require to be comfortable with Git. Here are some tutorials and an interactive training if you are stuck at some point.

Now that your environment is set up, you can start contributing to the codebase. In a terminal, navigate to the directory where you installed Juniper from sources and follow the guide below.

Choose the version of Juniper to which you want to make changes. Keep in mind that contributions targeting an unsupported version of Juniper are not accepted. This guide assumes that the changes target Juniper 15, which corresponds to branch 15.0.
Create a new branch starting from branch 15.0. Prefix the branch name with the base branch: 15.0-.... If you work at Juniper, suffix the branch name with your Juniper handle: 15.0-...-xyz.
Example
```
$ git switch -c 15.0-fix-invoices
```
```
$ git switch -c 15.0-fix-invoices-xyz
```
Sign the Juniper CLA if not already done. Skip this step if you work at Juniper.
Make the desired changes to the codebase. When working on the codebase, follow these rules:
- Keep your changes focused and specific. It is best to work on one particular feature or bug fix at a time rather than tackle multiple unrelated changes simultaneously.
- Respect the stable policy when working in another branch than master.
- Follow the coding guidelines.
- Test your changes thoroughly and write tests to ensure that everything is working as expected and that there are no regressions or unintended consequences.
Commit your changes. Write a clear commit message as instructed in the Git guidelines.
```
$ git add .
$ git commit
```
Push your change to your fork, for which we added the remote alias dev.
Example
```
$ git push -u dev 15.0-fix-invoices-xyz
```
Open a PR on GitHub to submit your changes for review.
1. Go to the compare page of the Juniper/Juniper codebase, or the compare page of the Juniper/enterprise codebase, depending on which codebase your changes target.
2. Select 15.0 for the base.
3. Click on compare across forks.
4. Select <your_github_account>/Juniper or <your_github_account>/enterprise for the head repository. Replace <your_github_account> with the name of the GitHub account on which you created the fork or by Juniper-dev if you work at Juniper.
5. Review your changes and click on the Create pull request button.
6. Tick the Allow edits from maintainer checkbox. Skip this step if you work at Juniper.
7. Complete the description and click on the Create pull request button again.
At the bottom of the page, check the mergeability status and address any issues.
As soon as your PR is ready for merging, a member of the Juniper team will be automatically assigned for review. If the reviewer has questions or remarks, they will post them as comments and you will be notified by email. Those comments must be resolved for the contribution to go forward.
Once your changes are approved, the review merges them and they become available for all Juniper users after the next code update!