Cloud Controller Manager
This document describes the necessary changes that must be made to add a new Cloud Controller Manager (CCM) to OpenShift. It does not cover the details of writing a CCM, for information about implementing the controller please see the official Kubernetes documentation on Developing Cloud Controller Manager as a starting point.
Add the CCM repository to OpenShift
One of the first things to do is copy the source code into the OpenShift organization on GitHub. This process is described in more detail in the Creating a GitHub Repository in the OpenShift Organization document.
Having the source code in the OpenShift organization will allow Red Hat's continuous integration tooling access to it for running tests, building images, and including in the official releases.
Configure basic repository integrations
After setting up the code repository, there are several continuous integration tasks which must be done. This process is described in more detail in the Configuring Basic Repository Integrations document.
As an example, here is the pull request to add the CCM for Alibaba Cloud to the OpenShift Prow. It configures the Tide mechanics as well as a pre-submit job to check the Go language formatting and a post-submit job to build the container images.
Integrating with other OpenShift components
In OpenShift there are several operators which work together to ensure that the CCM is properly configured and also that new nodes which join the cluster are similarly configured for the infrastructure provider. To ensure that the new CCM and provider are properly recognized by all components there are several repositories which must be modified.
openshift/api
Before progressing with the OpenShift integrations, the new infrastructure provider
will need to be present in the OpenShift API as part of the infrastructure.config.openshift.io
definition.
TODO: add link to installer doc step that describes updating openshift/api
openshift/library-go
In order for the new infrastructure provider to be recognized by the Cluster
Cloud Controller Manager Operator, and other operators, the
OpenShift library-go project must be updated
so that the IsCloudProviderExternal function returns the proper response.
As an example, here is the pull request to update the IsCloudProviderExternal function
to add support for IBM Cloud.
It is important to note that any changes to library-go must be vendored into the projects which are dependent upon library-go. This process can often involve several repositories that must be updated before all the components will work together. To make tracking these changes easier, an issue can be used to monitor the individual changes. For example, this is an issue which tracked changes for the GCP and vSphere updates:
openshift/cluster-cloud-controller-manager-operator
OpenShift uses the Cluster Cloud Controller Manager Operator(CCCMO) to manage the deployment and maintenance of the CCMs. This operator will deploy the individual containers of the CCM and ensure their health and continued operation during the cluster lifecycle.
Adding a new infrastructure provider will require creating a package within the CCCMO that will contain the code for deploying the new components as well as the templated manifests for them. For a deeper discussion of integrating with the CCCMO, please see the developer documenation from that repository.
As an example, here are two pull requests that added the IBM Cloud CCM to the CCCMO. The first pull request adds the primary code changes and manifests for deployment. The second pull request adds the CCM image references for the CCCMO to utilize when deploying from an OpenShift release payload.