Understanding YAML triggers

This is an important topic since YAML pipelines don’t have a graphical UI to define triggers and schedules for the pipelines.

All the steps will be done in the trigger section of the YAML file. It defines which branches will automatically run the pipeline when a push (commit or merge) happens.

trigger:
  - main
  - dev

Runs automatically when code is pushed to main or dev.

Specify branches #

You can use include and exclude rules to select which branches trigger a pipeline:

trigger:
  branches:
    include:
      - main
      - releases/*
    exclude:
      - dev/*

The example above will:

• Includes pushes to main and any branch starting with releases/ (e.g. releases/1.0).
• Excludes pushes to dev/* branches, even if they match an include pattern.

If you use both include and exclude, the exclude rules take precedence.

Disable All Branch Triggers #

trigger: none

Use this if you want to run the pipeline manually, for example.

Schedules #

With the schedules keyword, you can run your pipeline automatically at specific times (like nightly or weekly builds).

This is what it looks like:

schedules:
  - cron: "0 3 * * 1-5"   # Every weekday at 03:00 UTC
    displayName: Weekday Nightly Build
    branches:
      include:
        - main
    always: true

Now let’s see what the parameters are:

• cron: Standard cron format (minute hour day month day-of-week), it runs at 03:00 UTC, Monday to Friday. The times are always in UTC. You need to calculate the time depending on your time zone.
• branches.include: Runs the schedule only for the main branch.
• always: true: Runs even if there were no new commits since the last run. Use false if you want to only trigger the build when there are code changes.

If you’re not familiar with the cron format, here’s a crontab expression generator. Using ChatGPT/Copilot is quite helpful as well.