DevOps Classroom Series – 22/Dec/2019 – Jenkins Distributed Build

Jenkins Build Triggers

• Will help in triggering the Jenkins Build based on
  • Schedule:
    • Periodic: eg. Every 1 hour, Every 2 hours etc
    • On Schedule: eg Every weekday at 3 AM
  • Git Commits: Any new commits to Git Repo. Two ways of doing this
    • POll SCM: Jenkins will poll Git
    • Git/Web Hooks: Git will inform Jenkins whenever new commits happen
  • After Other Jobs are Built

Build Periodically

• Here you configure the schedules by using syntax whichi is much like cron jobs.

MINUTE HOUR DOM MONTH DOW
H/15 * * * *
0 4,15 * * *

Poll SCM

• Triggers a build whenever changes appear in git.
• Using Jenkins, user should describe how frequently poll should happen. For this we use the same syntax mentioned above

Build Environment

• Some of the Prebuild Actions such as cleaning workspace
• Build Settings such when build is taking more time , abort/fail etc can be configured
• Additions to console logs

Jenkins Logical Architecture

Queue

• Any build from Jenkins will be sent to Queue.
• It stays in the Queue till it finds free executor

Executor

• Is Execution unit of Jenkins (This is where build happens)
• Number of Executors signify number of parallel builds that can happen
• By Default, A project if it is under execution , will not be executed by other executors (Clicking Build now twice on same project will not lead to two executors)

Jenkins Distributed Builds

• Two kinds of Server Components are present in Jenkins
  • Master:
    • Jenkins Service will be running
    • Jenkins Home directory will be present
    • Communicates with Jenkins Agents using SSH/TCP (jnlp)
  • Node
    • Jenkins Agent will be running
    • Only the builds workspaces scheduled will be available
    • Every Agent should have some labels.