moby--moby/docs/sources/project/make-a-contribution.md

page_title: Make a project contribution page_description: Basic workflow for Docker contributions page_keywords: contribute, pull request, review, workflow, white-belt, black-belt, squash, commit

Make a project contribution

Contributing is a process where you work with Docker maintainers and the community to improve Docker. There is a formal process for contributing. We try to keep our contribution process simple so you want to come back.

In this section, you will create a new branch and work on some Docker code that you choose. Before you work through this process, take a few minutes to read through the next section which explains our basic contribution workflow.

The basic contribution workflow

You are about to work through our basic contribution workflow by fixing a single white-belt issue in the docker/docker repository. The workflow for fixing simple issues looks like this:

All Docker repositories have code and documentation. This workflow works for either content type. For example, you can find and fix doc or code issues. Also, you can propose a new Docker feature or propose a new Docker tutorial.

Some workflow stages have slight differences for code or documentation contributions. When you reach that point in the flow, we make sure to tell you.

Find and claim an existing issue

An existing issue is something reported by a Docker user. As issues come in, our maintainers triage them. Triage is its own topic. For now, it is important for you to know that triage includes ranking issues according to difficulty.

Triaged issues have either a white-belt or black-belt label. A white-belt issue is considered an easier issue. Issues can have more than one label, for example, bug, improvement, project/doc, and so forth. These other labels are there for filtering purposes but you might also find them helpful.

In the next procedure, you find and claim an open white-belt issue.

1. Go to the docker/docker repository.

2. Click on the "Issues" link.

   A list of the open issues appears.

   

3. Look for the white-belt items on the list.

4. Click on the "labels" dropdown and select white-belt.

   The system filters to show only open white-belt issues.

5. Open an issue that interests you.

   The comments on the issues can tell you both the problem and the potential solution.

6. Make sure that no other user has chosen to work on the issue.

   We don't allow external contributors to assign issues to themselves, so you need to read the comments to find if a user claimed an issue by saying:

   • "I'd love to give this a try~"
   • "I'll work on this!"
   • "I'll take this."

   The community is very good about claiming issues explicitly.

7. When you find an open issue that both interests you and is unclaimed, claim it yourself by adding a comment.

   

   This example uses issue 11038. Your issue # will be different depending on what you claimed.

8. Make a note of the issue number; you'll need it later.

Sync your fork and create a new branch

If you have followed along in this guide, you forked the docker/docker repository. Maybe that was an hour ago or a few days ago. In any case, before you start working on your issue, sync your repository with the upstream docker/docker master. Syncing ensures your repository has the latest changes.

To sync your repository:

1. Open a terminal on your local host.

2. Change directory to the docker-fork root.

    $ cd ~/repos/docker-fork
   

3. Checkout the master branch.

    $ git checkout master
    Switched to branch 'master'
    Your branch is up-to-date with 'origin/master'.
   

   Recall that origin/master is a branch on your remote GitHub repository.

4. Make sure you have the upstream remote docker/docker by listing them.

    $ git remote -v
    origin	https://github.com/moxiegirl/docker.git (fetch)
    origin	https://github.com/moxiegirl/docker.git (push)
    upstream	https://github.com/docker/docker.git (fetch)
    upstream	https://github.com/docker/docker.git (
   

   If the upstream is missing, add it.

    $ git remote add upstream https://github.com/docker/docker.git
   

5. Fetch all the changes from the upstream/master branch.

    $ git fetch upstream/master
    remote: Counting objects: 141, done.
    remote: Compressing objects: 100% (29/29), done.
    remote: Total 141 (delta 52), reused 46 (delta 46), pack-reused 66
    Receiving objects: 100% (141/141), 112.43 KiB | 0 bytes/s, done.
    Resolving deltas: 100% (79/79), done.
    From github.com:docker/docker
       9ffdf1e..01d09e4  docs       -> upstream/docs
       05ba127..ac2521b  master     -> upstream/master
   

   This command says get all the changes from the master branch belonging to the upstream remote.

6. Rebase your local master with the upstream/master.

    $ git rebase upstream/master
    First, rewinding head to replay your work on top of it...
    Fast-forwarded master to upstream/master.
   

   This command writes all the commits from the upstream branch into your local branch.

7. Check the status of your local branch.

   $ git status
   On branch master
   Your branch is ahead of 'origin/master' by 38 commits.
     (use "git push" to publish your local commits)
   nothing to commit, working directory clean
   

   Your local repository now has any changes from the upstream remote. You need to push the changes to your own remote fork which is origin/master.

8. Push the rebased master to origin/master.

    $ git push
    Username for 'https://github.com': moxiegirl
    Password for 'https://moxiegirl@github.com': 
    Counting objects: 223, done.
    Compressing objects: 100% (38/38), done.
    Writing objects: 100% (69/69), 8.76 KiB | 0 bytes/s, done.
    Total 69 (delta 53), reused 47 (delta 31)
    To https://github.com/moxiegirl/docker.git
       8e107a9..5035fa1  master -> master
   

9. Create a new feature branch to work on your issue.

   Your branch name should have the format XXXX-descriptive where XXXX is the issue number you are working on. For example:

    $ git checkout -b 11038-fix-rhel-link
    Switched to a new branch '11038-fix-rhel-link'
   

   Your branch should be up-to-date with the upstream/master. Why? Because you branched off a freshly synced master. Let's check this anyway in the next step.

10. Rebase your branch from upstream/master.

     $ git rebase upstream/master
     Current branch 11038-fix-rhel-link is up to date.
    

    At this point, your local branch, your remote repository, and the Docker repository all have identical code. You are ready to make changesfor your issues.

Work on your issue

The work you do for your issue depends on the specific issue you picked. This section gives you a step-by-step workflow. Where appropriate, it provides command examples. However, this is a generalized workflow, depending on your issue you may you may repeat steps or even skip some. How much time it takes you depends on you --- you could spend days or 30 minutes of your time.

Follow this workflow as you work:

1. Review the appropriate style guide.

   If you are changing code, review the coding style guide. Changing documentation? Review the documentation style guide.

2. Make changes in your feature branch.

   Your feature branch you created in the last section. Here you use the development container. If you are making a code change, you can mount your source into a development container and iterate that way. For documentation alone, you can work on your local host.

   Review if you forgot the details of working with a container.

3. Test your changes as you work.

   If you have followed along with the guide, you know the make test target runs the entire test suite and make docs builds the documentation. If you forgot the other test targets, see the documentation for testing both code and documentation.

4. For code changes, add unit tests if appropriate.

   If you add new functionality or change existing functionality, you should add a unit test also. Use the existing test files for inspiration. Aren't sure if you need tests? Skip this step; you can add them later in the process if necessary.

5. Format your source files correctly.

   File type	How to format
   .go	Format .go files using the gofmt command. For example, if you edited the `docker.go` file you would format the file like this: $ gofmt -s -w file.go Most file editors have a plugin to format for you. Check your editor's documentation.
   .md and non-.go files	Wrap lines to 80 characters.

6. List your changes.

    $ git status
    On branch 11038-fix-rhel-link
    Changes not staged for commit:
      (use "git add <file>..." to update what will be committed)
      (use "git checkout -- <file>..." to discard changes in working directory)
   
    modified:   docs/sources/installation/mac.md
    modified:   docs/sources/installation/rhel.md
   

   The status command lists what changed in the repository. Make sure you see the changes you expect.

7. Add your change to Git.

    $ git add docs/sources/installation/mac.md
    $ git add docs/sources/installation/rhel.md
   

8. Commit your changes making sure you use the -s flag to sign your work.

    $ git commit -s -m "Fixing RHEL link"
   

9. Push your change to your repository.

    $ git push --set-upstream origin 11038-fix-rhel-link
    Username for 'https://github.com': moxiegirl
    Password for 'https://moxiegirl@github.com': 
    Counting objects: 60, done.
    Compressing objects: 100% (7/7), done.
    Writing objects: 100% (7/7), 582 bytes | 0 bytes/s, done.
    Total 7 (delta 6), reused 0 (delta 0)
    To https://github.com/moxiegirl/docker.git
     * [new branch]      11038-fix-rhel-link -> 11038-fix-rhel-link
    Branch 11038-fix-rhel-link set up to track remote branch 11038-fix-rhel-link from origin.
   

10. Open your fork on GitHub to see your change.

Create a pull request to docker/docker

A pull request sends your code to the Docker maintainers for review. Your pull request goes from your forked repository to the docker/docker repository. You can see the list of active pull requests to Docker on GitHub.

To create a pull request for your change:

1. In a terminal window, go to the root of your docker-fork repository.

    $ cd ~/repos/docker-fork
   

2. Checkout your feature branch.

    $ git checkout 11038-fix-rhel-link
    Already on '11038-fix-rhel-link'
   

3. Run the full test suite on your branch.

    $ make test
   

   All the tests should pass. If they don't, find out why and correct the situation. If you also modified the documentation, run make docs and check your work.

4. Update your remote repository with any changes that result from your last minute checks.

   Use the git add, the git commit -s, and git push commands to do this.

5. Fetch any of the last minute changes from docker/docker.

    $ git fetch upstream master
    From github.com:docker/docker
     * branch            master     -> FETCH_HEAD
   

6. Squash your individual separate commits into one by using Git’s interactive rebase:

    $ git rebase -i upstream/master
   

   This commit will open up your favorite editor with all the comments from all your latest commits.

    pick 1a79f55 Tweak some of the other text for grammar
    pick 53e4983 Fix a link
    pick 3ce07bb Add a new line about RHEL
   

7. Replace the pick keyword with squash on all but the first commit.

    pick 1a79f55 Tweak some of the other text for grammar
    squash 53e4983 Fix a link
    squash 3ce07bb Add a new line about RHEL
   

   After closing the file, git opens your editor again to edit the commit message.

8. Save your commit message.

9. Push any changes to your fork on GitHub.

    $ git push origin 11038-fix-rhel-link
   

10. Open your browser to your fork on GitHub.

    You should see the latest activity from your branch.

    

11. Click "Compare & pull request".

    The system displays the pull request dialog.

    

    The pull request compares your changes to the master branch on the docker/docker repository.

12. Edit the dialog's description and add a reference to the issue you are fixing.

    GitHub helps you out by searching for the issue as you type.

    

13. Scroll down and verify the PR contains the commits and changes you expect.

    For example, is the file count correct? Are the changes in the files what you expect.

    

14. Press "Create pull request".

    The system creates the request and opens it for you in the docker/docker repository.

    

Your pull request under review

At this point, your pull request is reviewed. The first reviewer is Gordon. He might who might look slow in this picture:

He is actually pretty fast over a network. He checks your pull request (PR) for common problems like missing signatures. If Gordon finds a problem, he'll send an email to your GitHub user.

After Gordon, the core Docker maintainers look at your pull request and comment on it. The shortest comment you might see is LGTM which means looks-good-to-me. If you get an LGTM, that is a good thing, you passed that review.

For complex changes, maintainers may ask you questions or ask you to change something about your submission. All maintainer comments on a PR go to the email address associated with your GitHub account. Any GitHub user who "participates" in a PR receives an email to. Participating means creating or commenting on a PR.

Our maintainers are very experienced Docker users and open source contributors. So, they value your time and will try to work efficiently with you by keeping their comments specific and brief. If they ask you to make a change, you'll need to update your pull request with additional changes.

To update your existing pull request:

1. Change one or more files in your local docker-fork repository.

2. Commit the change with the git commit --amend command.

    $ git commit --amend 
   

   Git opens an editor containing your last commit message.

3. Adjust your last comment to reflect this new change.

    Added a new sentence per Anaud's suggestion	
   
    Signed-off-by: Mary Anthony <mary@docker.com>
   
    # Please enter the commit message for your changes. Lines starting
    # with '#' will be ignored, and an empty message aborts the commit.
    # On branch 11038-fix-rhel-link
    # Your branch is up-to-date with 'origin/11038-fix-rhel-link'.
    #
    # Changes to be committed:
    #		modified:   docs/sources/installation/mac.md
    #		modified:   docs/sources/installation/rhel.md
   

4. Push to your origin.

    $ git push origin
   

5. Open your browser to your pull request on GitHub.

   You should see your pull request now contains your newly pushed code.

6. Add a comment to your pull request.

   GitHub only notifies PR participants when you comment. For example, you can mention that you updated your PR. Your comment alerts the maintainers that you made an update.

A change requires LGTMs from an absolute majority of an affected component's maintainers. For example, if you change docs/ and registry/ code, an absolute majority of the docs/ and the registry/ maintainers must approve your PR. Once you get approval, we merge your pull request into Docker's master code branch.

After the merge

It can take time to see a merged pull request in Docker's official release. A master build is available almost immediately though. Docker builds and updates its development binaries after each merge to master.

1. Browse to https://master.dockerproject.com/.

2. Look for the binary appropriate to your system.

3. Download and run the binary.

   You might want to run the binary in a container though. This will keep your local host environment clean.

4. View any documentation changes at docs.master.dockerproject.com.

Once you've verified everything merged, feel free to delete your feature branch from your fork. For information on how to do this, see the GitHub help on deleting branches.

Where to go next

At this point, you have completed all the basic tasks in our contributors guide. If you enjoyed contributing, let us know by completing another white-belt issue or two. We really appreciate the help.

If you are very experienced and want to make a major change, go onto learn about advanced contributing.