Can I have a cron job pipeline trigger that only runs when code is changed?

Question

In Azure Devops we had nightly builds via pipelines and there was a checkbox to say "only run this if code has changed"

Now we have to use bitbucket, and we use the cron job pipeline trigger feature, but it runs every night even if there is no need to?

Robert Hiles · Answer

Building on the earlier suggestions, a more reliable guard than a fixed time window is to record the commit hash from the last successful nightly build and compare it with the current HEAD at the start of the scheduled pipeline. If the hashes match, exit early without running the heavier steps, and if they differ, run the build and update the stored hash only after it succeeds. That way a missed night does not cause an unnecessary run or skip a build that is still pending.

Arkadiusz Wroblewski · Answer

Hi @Jan Martin

One addition to Jairo's answer.

Checking commits from the last 24 hours can be unreliable, especially if a scheduled build is missed. A better method is to compare the current commit SHA with the last successful one. An external cron job can check for changes and trigger Bitbucket via its REST API only when necessary.

https://developer.atlassian.com/cloud/bitbucket/rest/api-group-pipelines/

Atlassian also has a feature request for this:

https://jira.atlassian.com/browse/BCLOUD-20166

Best,

Arek🤠🧙‍♂️

Jairo Merea · Answer

Hi Abdul,

Bitbucket doesn't have a native option to prevent a Scheduled Pipeline from running if there are no recent code changes u.u. To address this, you can opt for the solution provided a few years ago by Patrik S. https://community.atlassian.com/forums/discussion/2057955/bitbucket-pipelines-run-or-skip-step-based-on-condition-and-schedule

It consists of reusing your task logic using anchors (&my-step-anchor). You define a default pipeline that validates paths with changesets for regular commits, and create a dedicated custom pipeline for the Cron job.

YAML

definitions: 
  steps:
    - step: &my-step-anchor
        name: Build and test
        script:
          - echo "Executing process"
 pipelines:
  default: 
    - step:
        <<: *my-step-anchor
        condition:
          changesets:
            includePaths:
              - "src/**"                    
  custom: 
    customPipelineForSchedule: 
      - step: *my-step-anchor

The issue is that the scheduled pipeline will execute completely in every cycle, regardless of whether the code changed or not.

However, you can also add a validation at the beginning of your script to check the Git history. If it doesn't detect recent commits, it forces an early successful exit (exit 0), stopping the container.

YAML

clone:
  depth: full

pipelines:
  custom:
    tareas-programadas:
      - step:
          script:
            - CAMBIOS=$(git log --since="24 hours ago" --oneline)
            - if [ -z "$CAMBIOS" ]; then echo "No changes."; exit 0; fi
            - echo "Executing tasks..."

* Pros: Saves build minutes by avoiding compilation or test execution when there has been no activity.
* Cons: Consumes a small initial overhead (15 to 30 seconds) while Bitbucket spins up the container and clones the repository. Additionally, it requires setting clone: depth: full and ensuring your Docker image includes Git.