Jenkins Pipeline Triggers

What are the different ways to trigger Jenkins pipelines?

Jenkins pipelines can be triggered in various ways, depending on your use case and environment. Here are some common methods:

1. Manually from the Jenkins UI

• You can manually trigger a pipeline by navigating to the Jenkins job in the Jenkins web interface and clicking the “Build Now” button.

2. Webhook Triggers (GitHub, GitLab, Bitbucket, etc.)

• Jenkins pipelines can be triggered by webhooks from version control systems like GitHub, GitLab, or Bitbucket.

• When a push or pull request event occurs in the repository, a webhook triggers the pipeline.

3. Poll SCM

• Jenkins can periodically check the source code repository for changes using the Poll SCM feature.

• You define a cron-like schedule, and Jenkins checks for any updates. If changes are detected, the pipeline starts automatically.

4. Scheduled Builds (Cron Jobs)

• You can schedule pipelines to run at specific times using cron syntax in Jenkins.

• This is useful for nightly builds or periodic maintenance tasks.

5. Trigger from Other Jenkins Jobs

• Pipelines can be triggered as part of a downstream process from another Jenkins job.

• This can be achieved using “Build Trigger” options like “Build after other projects are built”.

6. Trigger via REST API

• Jenkins provides a REST API that can be used to trigger builds programmatically.

• You can send a HTTP POST request to Jenkins to start a build with or without parameters.

7. Git Hooks (on Git Server)

• Similar to webhooks, git hooks on the repository can be configured to send signals to Jenkins to trigger builds based on certain events like git push.

8. Parameterized Builds

• Pipelines can be triggered manually or automatically with specific parameters (e.g., branch, environment).

• These parameters can be set when triggering the pipeline from the Jenkins UI, REST API, or another job.

9. Using Jenkinsfile (Declarative Pipeline)

• In a Jenkinsfile, you can define triggers like cron or pollSCM within the pipeline script itself, which will automatically schedule builds or poll for changes.

Example:

pipeline {

  triggers {

        cron('H 4/* 0 0 1-5') // Trigger every day at 4 AM.

  }

}

10. Build Triggers from External Tools

• Jenkins pipelines can be triggered by external tools like Ansible, Terraform, or any automation platform via API or script integrations.

11. Jenkins CLI

• Jenkins also provides a command-line interface (CLI) that allows you to trigger builds from the terminal.

12. Git Plugin (Branch Specifiers)

• You can set branch-specific pipelines to trigger based on changes in specific branches using the Git Plugin.

These options provide flexibility for continuous integration and delivery workflows, allowing teams to tailor how pipelines are triggered based on their project needs.