Implement EKS provisioning and support multiple provisioners.

[gargravarr]

This Pull Request updates the eks-support branch with the following changes:

• Updates the CLM entry point support both Zalando AWS end EKS provisioning. I replaced the main provisioner instance with a map of provisioners. This map replaces the single provisioner parameter in the control loop, while command line picks the provisioner based on the specified provider.
• Splits EKS and self-managed provisioning in two structs: ZalandoAWSProvisioner and ZalandoEKSProvisioner:
  • ZalandoAWSProvisioner: just calls the provisioning/decommissioning methods of clusterPyProvisioner.
  • ZalandoEKSProvisioner: creates the EKS token source before calling provisioning/decommissioning methods of clusterPyProvisioner. Additionally for decommissioning passes the specific Certificate Authority data.
• Adds a ProvisionModifier interface. EKS Provisioning implements this interface, and the clusterPyProvisioner calls back GetPostOptions. When provisioning EKS, only after this stage it is possible to know some configuration necessary to provision a cluster, like: API Server endpoint, custom Certificate Authority, and Availability Zone information.
• Updates clusterpyProvisioner in the following:
  • Adds a provider field and implements a common Supports method.
  • Adds an optional modifier, which maybe used at a later provisioning stage
  • Hides the interface from outside provisioner (the provisioners have a clusterPyProvisioner as a field).
  • Provides the AWS Adapter as a parameter to provision(). The EKS provisioner needs this adapter before provisioning, to build a token source.
  • Refactors prepareProvision() to only apply default valuers to the various manifests. Gathering instance type information from AWS is now done by provision.
  • Calls back a modifier interface right after applying the first cluster.yaml CloudFormation.
  • Adds an optional Certificate Authority data to decommission(), necessary for decommissioning an EKS cluster.
• Updates the lower level Kubernetes functions (found in pkg/kubernetes) with support an optional parameter with custom Certificate Authority data. This certificate is necessary when provisioning an EKS cluster.
• Removes the token source parameter when creating the AWS Adapter. The token source is not used by the adapter.

This Pull Request does not add tests. A follow-up Pull Request to master will have more testing.

[linki]

👍

[gargravarr]

:+1: