Image build

The appliance always uses the ansible in ansible/site.yml but this can be used in two ways:

1. To directly configure VMs.
2. To build an image in Packer, which can subsequently be deployed to VMs.

It is recommended that:

• An initial deployment is done by directly configuring VMs, probably on a smaller cluster than the final goal. This enables any bugs in config, networking, DNS etc to be worked out. The ansible/adhoc/tests.yml can be run to check hardware/software stack performance is as expected.
• Once happy, it is strongly recommended that images are built and deployed to the final cluster. This ensures that nodes are replaceable as it protects against changes in upstream repos (e.g. OpenHPC releases) which may make subsequent directly-configured nodes incompatible with the existing cluster.

If using dev/staging/prod environments consider:

• Using direct configuration in dev
• Testing built images in staging
• Only deploying images in prod