CI best practices

Continuous Integration - best practices

General tips

• keep the builds and tests fast!
  • true to the XP spirit, turnaround time between check in and feedback (build successful/failed) should be kept to a minimum
  • long running builds and tests should be split up
    • eg. into staged tests: test a few basic things first and only if they are successful, run more detailed tests
• a CI server is not a build artifact repository or storage server!
  • build artifacts in general should be seen as ephemeral
  • if a build artifact is considered a milestone, release candidate, release, etc. it should be copied to a storage server (eg. downloads.eclipse.org)
  • public announcements like "You can get the latest release from our Hudson/Jenkins instance" are considered to be bad practice

Job configuration smells

• build logic leaks to job
• too many build steps
• shell steps
• not under SCM

Source: https://narkisr.github.io/jenkins-scaling/#configuration-smells

Deal with branches

• managing branches from UI results in duplication, create a template project and clone, use programmatic API instead

Disk usage

Builds and tests can consume large amounts of data while checking out Git repositories, downloading Maven artifacts and compiling multi-OS, multi-arch, multi-bitness artifacts, etc.
Disk space is cheap, but not free (yet). Therefore disk usage should be reasonable.

Here is a rough guideline for HIPPs/JIPPs:

• up to 50GB of disk space is considered to be fine.
• 50-100GB is mostly considered to be OK, if it has no impact on other projects.
• upwards of 100GB is considered to be excessive and you should check your job structure/configurations

As always there are exceptions to that rule. If a project has a good reason to use a lot of disk space this will be respected.
If not, you will be notified and ultimately blamed publicly.

Build history

• a build history is a good indicator to track the health/stability/test coverage, etc. of your project
• since the build history can take up considerable large amounts of disk space it should be kept at bay
  • it's nice to see the last 500 builds, but in many cases 10-20 builds have nearly the same value to see trends
  • in most cases there is no benefit in keeping more than a few builds with their artifacts, especially if the size is in the 500MB+ range
  • console logs are important, but if all debug levels are dialed to 11, they can become quite big (100s of MB)
    • Hudson is not good at dealing with huge console logs, Jenkins is better
    • browsers in general don't like huge console logs
    • try to find a balance between huge logs and time spent to run a build again with different logging levels if something failed (maybe a log level parameter can help)

Old build jobs

• best case scenario: all your build configurations are stored in a SCM and you don't have to keep extra job configurations
• if a build job is deprecated or archived, consider deleting the workspace to save disk space