GoCD - Git feature branch support

This is a GoCD SCM plugin for Git feature branch support. Discussion Thread

Supported (as separate plugins):

• Git repository for branches
• Github repository for Pull Requests
• Gitlab repository for Merge Requests
• Stash repository for Pull Requests
• Gerrit repository for Change Sets

Migration from Git Feature Branch plugin 1.2.x to 1.3

Addition of the white and blacklist feature to Git Feature Branch plugin changes the identity of the SCM material. This means that it may trigger automatically triggered pipelines that use Git Feature Branch material. When moving from version 1.2.x to 1.3.x be sure to pause all pipelines which shouldn't be triggered or be ready to cancel them in case they are triggered.

Requirements

These plugins require GoCD version v15.x or above.

Get Started

Installation:

• Download the latest plugin jar from the Releases section. Place it in <go-server-location>/plugins/external & restart Go Server. You can find the location of the Go Server installation here.
• One more thing to note: The release section contains different plugins for different SCM types. Select the one which is a correct match for your desired SCM type. Choosing mismatching plugins will cause weird issues.

Usage:

• Make sure plugins are loaded. Note: You can use GoCD build status notifier to update status of Pull Requests with build status.

• Assuming you already have a pipeline "ProjectA" for one of your repos

• 'Extract Template' from the pipeline, if its not templatized already (this is optional step)

• Create new pipeline say "ProjectA-FeatureBranch" off of the extracted template. You can clone "ProjectA" pipeline to achieve this.

• In the materials configuration for your newly created pipeline, you will see that there is a new material for each of the plugins you have installed (Git Feature Branch, Github, Stash or Gerrit). Select one of these new materials, fill in the details and the plugin will build the pull requests from the given material.

• You can delete the old material that is left over from cloning your pipeline.

Behavior

• First run of the new pipeline will be off of the 'Default Branch' configured in the Material. This creates base PR-Revision map. It also serves as sanity check for newly created pipeline.

• From then on, any new change (new PR create / new commits to existing PR) will trigger the new pipeline.

• PR details (id, author etc.) will be available as environment variables for tasks to consume.

• Build status notifier plugin will update Pull Request with build status

Github

Authentication:

• You can create a file ~/.github with the following contents: (Note: ~/.github needs to be available on Go Server)

login=johndoe
password=thisaintapassword

• You can also generate & use oauth token. To do so create a file ~/.github with the following contents: (Note: ~/.github needs to be available on Go Server)

login=johndoe
oauth=thisaintatoken

Github Enterprise:

• If you intend to use this plugin with 'Github Enterprise' then add the following content in ~/.github (Note: ~/.github needs to be available on Go Server)

# for enterprise installations - Make sure to add /api/v3 to the hostname
# ignore this field or have the value to https://api.github.com
endpoint=http://code.yourcompany.com/api/v3

Environment Variables

When working with Github PR material, we also make available the following list of environment variables in the pipeline.

Note: Their name will vary depending on your material's name. For example, if you name it my-material, they will be available under GO_SCM_MY_MATERIAL_* prefix.

Troubleshooting: Those variables will be seen only if you have managed to setup GH authentication correctly. See this comment for more info. (Otherwise, you might end up with a situation in which the PR pipeline is triggered, but is missing the env variables.)

Environment Variable	Description
GO_SCM_*_PR_BRANCH	Pull Request was submitted from this organisation/user and branch. Eg. ashwankthkumar:feature-1
GO_SCM_*_TARGET_BRANCH	Pull Request was submitted for this organisation/user and branch. Eg. ashwankthkumar:master
GO_SCM_*_PR_ID	Pull Request ID on the Github
GO_SCM_*_PR_URL	Pull Request URL on the Github
GO_SCM_*_PR_AUTHOR_EMAIL	Email address of the author who submitted the Pull Request.
Note: This is subject to availability on their Github profile.
GO_SCM_*_PR_TITLE	Title of the Pull Request
GO_SCM_*_PR_DESCRIPTION	Description of the Pull Request

Gitlab / Gitlab Enterprise

Authentication:

• You can create a file ~/.gitlab with the following contents: (Note: ~/.gitlab needs to be available on Go Server)

login=johndoe
accessToken=personalaccesstoken

Please refer this link for more details on how to create a personal access token.

Stash

Authentication

If authentication is required, place a file named .netrc under the Go user's home directory. The file needs to be created in both the server and any number of agents that will build this material. You can find the home directory for Go server here and for Go Agent here.

The .netrc file takes the following format:

machine stash.vm.com 
login myusername
password mypassword

Git

Branch filtering

Git feature branches support filtering the branches with whitelist and blacklist. Both lists support glob syntax (*, ?, [...], {...}) and multiple branch patterns can be given as a comma separated list. The glob syntax is same as defined in Java's FileSystem.getPathMatcher() method. If neither blacklist or whitelist pattern is defined, all branches will be built.

The blacklist takes precedence over whitelist. I.e. a branch will not be built if the blacklist pattern matches to the branch name.

To Dos

• Clean up the code esp. the JSON SerDe part
• Add proper tests around the plugin

FAQs

Pull Request isn't being built

• If more than 1 PR gets updated (create/update) Go bunches them together for the next pipeline run & uses the top change in the "build-cause" to build. You can force trigger pipeline with other revisions until this get fixed (thread).