rebazer

Helper service to handle pull requests (PRs) on GitHub or Bitbucket. Primary it rebases the source branch of PRs against target branch to streamline commit history.

The rebazer polls in a configurable interval GitHub and Bitbucket repositories. The processing for each repository is described below:

• Has PR changed since last run?
  • If no wait again for source/target branch, build result or approval change
• Is the corresponding build green?
  • If no wait again for green build
• Is source branch on top of target branch?
  • Rebase source branch
  • Conflict while rebasing?
    • On conflict abort rebase and comment PR
  • Wait for green build
• Is PR approved?
  • Wait for approval
• Merge PR into
• Delete merged branch

Illustrated as a flowchart:

Configuration

The rebazer relies on several parameters to configure the handled repositories. The configuration can be specified in any way supported by spring boot. Recommended is to use a application.yml file. The roll out of the application.yml depends on type of deployment.

Minimal configuration example:

rebazer: hosts: - type: GITHUB teams: - name: your_company user: service_user pass: dont_use_this_pass_at_home repos: - name: foo - name: bar

An example in-depth can be found in application-example.yml.

Mandatory parameter

Parameter	Explanation
rebazer.hosts[ ].type	Hosting platform type, possible values GITHUB or BITBUCKET
rebazer.hosts[ ].teams[ ].name	Team/company/project name of the repos, first part of the slug
rebazer.hosts[ ].teams[ ].pass	Password to access the repositories
rebazer.hosts[ ].teams[ ].repos[ ].name	Name/Key of a specific repository

Optional parameter

Parameter	Explanation	Default Value
rebazer.workspace	Workspace Directory for checkouts	./rebazer-workspace
rebazer.garbageCollectionCountdown	Number of rebases before a git GC is triggered	20
rebazer.pollInterval	Delay in seconds between checks for changes on configured repos	60
rebazer.hosts[ ].url	Base URL to the hosting platform api	Depents on ..hosts[ ].type, e.g. https://api.github.com
rebazer.hosts[ ].teams[ ].user	User for the specific team to access repositories	Same as ..teams[ ].name
rebazer.hosts[ ].teams[ ].repos[ ].mainBranch	Branch to reset git repo on cleanup after rebase	main

Deployment

Spring Application JAR

This JAR can basically be run everywhere a JVM is present; there are no further dependencies. However, for a successful start, several parameters need to be configured (see configuration section for details). There are quite a number of ways to specify these parameters.

If e.g. all parameters are specified in a file called application.yml, the following command should be sufficient for starting rebazer:

java -jar rebazer-VERSION.jar --spring.config.location=file:./application.yml

Docker

We provide a docker image on docker hub. An example configuration for the docker container is placed in the docker-compose.yml.

To configure the rebazer mount the configuration file at /application.yml. To optimize production setups it is recommended to mount /rebazer-workspace as an external storage or ram disk.

Example:

docker run -v $(pwd)/application.yml:/application.yml -e SPRING_CONFIG_LOCATION=file:/application.yml retest/rebazer

Debian package

Attention: We don't ship a fully functional configuration for this package. So after installation, one must ensure that a proper configuration is placed in /etc/rebazer. Also make sure that the configuration file is accessible by the user rebazer.

This package automatically creates:

• System user for running rebazer
• Proper logging via systemd/syslog (to /var/log/rebazer)
• Systemd service named rebazer.service
• Workspace in /var/lib/rebazer (can be configured in /etc/defaults/rebazer)

The debian package overwrites the rebazer.workspace parameter via an environment variable.

Troubleshooting

Symptom: Errors during startup

Solution: Please make sure the folder /etc/rebazer contains a valid configuration and the user rebazer has access to it.

chmod 755 /etc/rebazer
chmod 600 /etc/rebazer/application.yml
chown rebazer:rebazer /etc/rebazer/application.yml

Build

Build prerequisites

Before building the rebazer application, please make sure that the following tools are installed:

• Java 8
• Maven (3.3+)
• Git

A typical build involves calling the package target via maven from the root of the cloned repository:

mvn clean package

The major artifacts are then build inside the target directory: rebazer-$VERSION.jar.

There are maven profiles to build docker or deb packages.

mvn clean package -P deb

mvn clean package -P docker

mvn clean package -P deb,docker