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Post-start

(See Job Lifecycle for an explanation of when post-start scripts run.)

Note

This feature is available with bosh-release v255.4+ and only for releases deployed with 3125+ stemcells.

Note

Releases that make use of post-start scripts and are deployed on older stemcells or with an older Director may potentially deploy; however, post-start script will not be called.

Release job can have a post-start script that will run after the job is started (specifically after monit successfully starts a process). This script allows the job to execute any additional commands against a machine and/or persistent data before considering release job as successfully started.

Job Configuration

To add a post-start script to a release job:

  1. Create a script with any name in the templates directory of a release job.
  2. In the templates section of the release job spec file, add the script name and the bin/post-start directory as a key value pair.

Example:

---
name: cassandra_node
templates:
  post-start.erb: bin/post-start

Script Implementation

Post-start script is usually just a regular shell script. Since post-start script is executed in a similar way as other release job scripts (start, stop, drain scripts) you can use job's package dependencies.

Post-start script should be idempotent. It may be called multiple times after process is successfully started.

Unlike a drain script, a post-start script uses an exit code to indicate its success (exit code 0) or failure (any other exit code).

Post-start script is called every time after job is started (ctl script is called) by the Director, which means that post-start script should perform its operations in an idempotent way.

Note

Running monit start directly on a VM will not trigger post-start scripts.

Post-start scripts in a single deployment job (typically is composed of multiple release jobs) are executed in parallel.

Logs

You can find logs for each release job's post-start script in the following locations:

  • stdout in /var/vcap/sys/log/<job-name>/post-start.stdout.log
  • stderr in /var/vcap/sys/log/<job-name>/post-start.stderr.log

Since post-start script will be called multiple times, new output will be appended to the files above. Standard log rotation policy applies.