The Automation Broker works in conjunction with the Kubernetes Service Catalog to make services and applications easily deployable. An end user selects a service to be provisioned, selects a "plan" that describes the level of service (small, large, paid, free, persistent, ephemeral, etc), and then provides any required parameters. In this scenario, Helm charts can be utilized in two possible ways.
- The Automation Broker's "helm registry adapter" can inspect a chart repository and make each discovered chart available as a service class. The chart's
values.yamlfile is made available as a single parameter for a single default plan.
- The tool
helm2bundlecreates a Service Bundle image that includes a specific chart. The image can be modified like any service bundle, including changes to metadata such as those in
This post explores how to use Ansible Automation with the latter option to extend the behavior of a helm bundle.
service bundle - a container image that represents a service class's metadata and behavior.
helm bundle - a service bundle that contains a helm chart.
APB - aka Ansible Playbook bundle, a service bundle that uses Ansible Automation.
Automate Chart Input
Helm charts, which take input as a free-form yaml file, can take advantage of Ansible Automation by being included in a helm bundle that is based on the
For example, the
stable/redis chart has a setting in its
values.yml that always needs to be changed in order to run in OpenShift. These are the steps to set that automatically based on Ansible facts.
Make the helm bundle
$ helm fetch stable/redis
$ helm2bundle redis-1.1.12.tar.gz
Create overrides template
helm-ansible-base image knows to look for a file called
overrides.yml.j2. If found, it gets rendered using ansible facts and then passed into helm as a settings file. It should be a subset of the values that are settable for the chart, as described in the chart's
Ours should look like this:
## Pod Security Context
Change the Dockerfile
Set the base image in the
helm-ansible-base, and add the overrides template file.
COPY redis-1.1.12.tgz /opt/chart.tgz
COPY overrides.yml.j2 /opt/overrides.yml.j2
If you build and use that Helm Bundle to provision Redis, it will create a new fact based on the value of an existing fact, and then use the new fact to render a helm settings file. Ansible made it easy for us to dynamically configure this setting. While this example is relatively trivial, the same technique can be employed to do much more sophisticated configuration.
In the next blog post, we will use a similar technique to add rich parameters to a helm bundle, so that the user input experience is easier than editing yaml.