How To: Stop monitoring a child pipeline once a step is reached


When running child builds from within a Codefresh build, sometimes you only need to monitor the progress of the child build up to a certain point, and don’t want the calling step to wait until the entire child build is done before proceeding.

For instance, you may need the parent pipeline to wait for some steps in a child build to finish, but don’t want the parent build to then wait for an approval step in the child to complete before moving on.

You can potentially run the child pipeline in detached mode with the DETACH: true argument (or -d option, if you are directly running the codefresh run CLI command). This way the parent pipeline will just start the child build and move on. But running with detached mode means that the parent build will not monitor the progress of the child build at all, which will cause issues if you still need things to run in a certain order.


If possible for your pipeline, the best approach would be to split off one additional pipeline from the child pipeline for every step that the top-level parent does not need to wait on, to be called by the child pipeline in detached mode. The top level parent build would wait for the child build to execute the first set of steps, the child build calls the grandchild in detached mode and immediately end, and the top level parent then resumes without waiting for steps in the grandchild to complete.

If this is not feasible given the structure of your pipeline, you can set up a freestyle step to start a child build using the codefresh run CLI command, then parse this command’s output for specific key words that mark the build reaching a certain state. Once a match has been found in the output, terminate the command so that the step can exit and the build can move on to the next step. The child build will continue running in the meantime.

This step will start a child build from the pipeline test/test_approval, wait for it to run until it reaches an approval step, then exit and move on to the rest of the pipeline.

    title: "Run Child PIpeline"
    type: "freestyle"
    image: "codefresh/cli:latest"
      - "{ codefresh run test/test_approval & echo $! > pid; } | { grep -m1 'Pending approval step reached, pausing workflow' && kill -9 $(cat pid) && rm pid; }"

You can modify this command to stop monitoring on specific steps by changing the match string. For example, running grep for the string Step: run_test will stop the monitoring once the child build has reached the step run_test.

Notes This second approach does require making assumptions about the build’s status based purely on console log output. Be careful that the string you’re matching for is truly unique to the state you’re watching for, and the same string is not duplicated elsewhere in the build. Likewise, if the log output for the state you’re watching for changes in any way, the match string will need to be updated.

This step will exit with status “success” once a match in the output is found.

If the child pipeline fails before this calling step stops monitoring, then this calling step will exit with status “failure.”

Because we are directly calling the CLI instead of using the plugin step, this method loses the link that would normally be able take you from the parent build to the child build, and makes them more difficult to track and manage.