openstack/tripleo-image-elements
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tripleo-image-elements/HACKING.rst
Alexis Lee c470a1b9c9 Create HACKING.rst for elements 
First item - idempotency of os-refresh-config scripts.

Change-Id: Idcf34021f5ec6fce80dec840d4eb37fecb75194b
2014-11-21 10:35:17 +00:00

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TripleO Style Guidelines

  • Step 1: Read the OpenStack Style Guidelines1.
  • Step 2: Read the tripleo-incubator HACKING.rst2.
  • Step 3: Read on.

Element Specific Guidelines

  • Idempotency. A new version of metadata can be pushed at any time, for example due to a heat stack-update. Elements' os-refresh-config scripts must handle this gracefully. If they cannot be fully idempotent, they must fence their once-only sections.

    For example, the keepalived element's configure.d script either reloads or restarts the service based on whether it appears to be already running. Another method of fencing would be to write a marker to ephemeral storage on first execution and skip once-only sections if the marker is present.

References

  1. http://docs.openstack.org/developer/hacking/↩︎

  2. http://docs.openstack.org/developer/tripleo-incubator/HACKING.html↩︎