How to use BOSH os-conf release to run script at different deployment stage

Products

• VMware Tanzu Kubernetes Grid Integrated Edition

Issue/Introduction

You may want to perform special task at some specific BOSH deployment stage. For example,

• Install a package which is not shipped with Stemcell by default
• Modify config file of some job on the BOSH instance

BOSH os-conf release contains the jobs which could help in such case at the following BOSH deployment stages.

• pre-start
• pre-stop
• post-deploy
• post-stop

This KB article provides an example to utilise pre-start-script job included in os-conf release to run some commands at pre-start stage of a BOSH deployment. BOSH runtime config is also used here to apply it on specific deployments/instance groups/jobs.

Environment

BOSH instances on Tanzu Platform

Resolution

1. Upload os-conf release to BOSH director

$ bosh upload-release --sha1=sha256:efcf30754ce4c5f308aedab3329d8d679f5967b2a4c3c453204c7cb10c7c5ed9   "https://bosh.io/d/github.com/cloudfoundry/os-conf-release?v=23.0.0"

 

2. Create BOSH runtime config to apply os-conf release job for specific BOSH instance group/deployment/job. 

For example, you have the following testdep deployment in your environment.

$ bosh -d testdep vms
Using environment '#.#.#.#' as client 'ops_manager'

Task 4542. Done

Deployment 'testdep'

Instance                                     Process State  AZ   IPs            VM CID                                   VM Type  Active  Stemcell  
master/d8cf70de-####-43b47c44a019            running        az1  #.#.#.#        vm-547853ad-####-7c1d1d1169c0            micro    true    bosh-vsphere-esxi-ubuntu-jammy-go_agent/1.866  
worker/7f24f10a-####-82e2e5a701b3            running        az1  #.#.#.#        vm-20df7a54-####-99806fd20a7b            micro    true    bosh-vsphere-esxi-ubuntu-jammy-go_agent/1.866  

Create a runtime config to apply the pre-start-script (or other scripts mentioned above) of the os-conf release to selected deployments/instance groups/jobs.

Refer to the BOSH document for details of runtime config properties.

For example, the following runtime config applies to the master/worker instance group shown previously.

$ cat osconf-runtime.yml 
releases:  
- name: os-conf   
  version: 23.0.0 

addons:
- name: osconf-prestart-config   
  jobs:      
  - name: pre-start-script        
    release: os-conf        
    properties:          
      script: |-
         #!/bin/bash
         if [ -f /var/vcap/jobs/bosh-dns/config/config.json ]; then
             echo "# this is a test " > /var/vcap/jobs/bosh-dns/config/osconf-test.txt
         fi
include:
  instance_groups:
  - master
  - worker

Create the runtime config

$ bosh update-runtime-config --name=osconf-prestart-config osconf-runtime.yml

 

3. Generate the manifest of this testdep deployment and deploy it again to apply the runtime config

$ bosh -d testdep deploy testdep_manifest.yml 
Using environment '#.#.#.#' as client 'ops_manager'

Using deployment 'testdep'

  releases:
+ - name: os-conf
+   version: 23.0.0
  
  addons:
+ - jobs:
+   - name: pre-start-script
+     properties:
+       script: "<redacted>"
+     release: os-conf
+   name: tkgi-prestart-config

Continue? [yN]: y
......

 

4. Verify the pre-start-script is executed successfully

$ bosh -d testdep ssh  -c 'sudo ls -l /var/vcap/jobs/bosh-dns/config/osconf-test.txt'  | grep stdout
worker/7f24f10a-####-82e2e5a701b3: stdout | -rw-r--r-- 1 root root 18 Oct 28 07:13 /var/vcap/jobs/bosh-dns/config/osconf-test.txt
master/d8cf70de-####-43b47c44a019: stdout | -rw-r--r-- 1 root root 18 Oct 28 07:12 /var/vcap/jobs/bosh-dns/config/osconf-test.txt

 

Additional Information

References

BOSH os-conf release Github repo

BOSH runtime config