Using Mistral to execute Workflows on an arbitrary cloud

It is possible to execute a workflow on any arbitrary cloud without additional configuration on the Mistral server side. It is possible to have Mistral use an external OpenStack cloud even when it isn’t deployed in an OpenStack environment (i.e. no Keystone integration).

This setup is particularly useful when Mistral is used in standalone mode, where the Mistral service is not part of the OpenStack cloud and runs separately.

To enable this operation, the user can use --os-target-username, --os-target-password, --os-target-tenant-id, --os-target-tenant-name, --os-target-auth-token, --os-target-auth-url, --os-target_cacert, and --os-target-region-name parameters.

For example, the user can return the heat stack list with this setup as shown below:

$ mistral \
    --os-target-auth-url= \
    --os-target-username=testuser \
    --os-target-tenant=testtenant \
    --os-target-password="MistralRuleZ" \
    --os-mistral-url= \
    run-action heat.stacks_list

The OS-TARGET-* parameters can be set in environment variables as:

$ export OS_TARGET_USERNAME=admin
$ export OS_TARGET_TENANT_NAME=tenant
$ export OS_TARGET_PASSWORD=secret
$ export OS_TARGET_REGION_NAME=region

Note on the –os-target_cacert parameter

The –os-target_cacert parameter can be used to set a CA certificate for SSL communication with the target cloud’s Keystone service. The CA certificate file is NOT transferred to the Mistral server. It is the responsibility of the user to ensure that the SSL Certificate is accessible for the Mistral Executor and SSL communication is possible with the target cloud. For testing purposes it is suggested to use the –target_insecure parameter.