Structure of a VM

All managed VMs include:

  • BOSH Agent
  • Monit daemon
  • /var/vcap/ directory

Each BOSH managed VM may be assigned a single copy of a deployment job to run. At that point VM is considered to be an instance of that deployment job -- it has a name and an index (e.g. redis-server/0).

When the assignment is made, the Agent will populate /var/vcap/jobs directory with the jobs specified in the instance group definition from the deployment manifest. If the jobs depend on packages, then those will also be downloaded and placed into the /var/vcap/packages directory. For example given a following deployment job definition:

- name: redis-master
  - {name: redis-server, release: redis}
  - {name: syslog-forwarder, release: syslog}

Then the Agent will download the two jobs into the following directories:

  • redis-server into /var/vcap/jobs/redis-server
  • syslog-forwarder into /var/vcap/jobs/syslog-forwarder

Assuming that the redis-server job depends on a redis package and the syslog-forwarder job depends on a syslog-forwarder package, the Agent will download two release packages into the following directories:

  • redis into /var/vcap/packages/redis
  • syslog-forwarder into /var/vcap/packages/syslog-forwarder