R & D: Enhancing the operational experience of Argo CD

Summary

Configuring Argo CD can be an arduous process with a growing number of configuration knobs in large configmaps and secrets. Example https://argoproj.github.io/argo-cd/operator-manual/argocd-cm.yaml

This enhancement proposal aims to introduce a set of strongly typed APIs a.k.a CRDs to make configuration of clusters, repository credentials, and health checks.

Motivation

• Make it extremely hard for operators to enter incorrect configuration.
• Operators should be able to define key configuration information as custom resources.
• Use the Kubernetes best practices to deprecate API attributes ( example ) .
• Provide feedback to operators as information in the `.status` section of the configuration object or deny admission of an incorrectly formatted configuration.

Goals

• Build a set of operator-focused APIs that hide the configuration information that goes into argocd-cm.yaml
• Use the operator-focused APIs to convey compatibility information to operators.

    Non-Goals

• Enhancing https://github.com/argoproj-labs/argocd-operator is a non-goal. We may consider having these controllers in a separate repo or the same as  https://github.com/argoproj-labs/argocd-operator . 
• This proposal doesn’t intend to define how the APIs would look in detail.
• This proposal doesn’t intend to define the exhaustive list of configurations.

Proposal

1. Define & manage a set of CRD/Controllers in a separate Github repository that simplify configuration of Argo CD.  
2. Define a Repository CRD and controller which watches Repository CRs and configures the relevant configmaps. argoproj/argo-cd/issues/5720
3. Define a CustomHealthCheck CRD and controller which watches CustomHealthCheck and  configures the relevant configmaps  argoproj/argo-cd/issues/5506
4. Define a ArgoCDConfig CRD and controller which watches ArgoCDConfig CRs and configures relevant configmaps that captures the equivalent of https://argoproj.github.io/argo-cd/operator-manual/argocd-cm.yaml for areas which aren’t covered by other CRDs.
5. argoproj/argo-cd/issues/5721Define a ConfigManagementPlugin CRD and controller which watches ConfigManagementPlugin CRs and configures the appropriate workloads

 These CRDs need may live with the Argo CD Operator project.

Use cases

Use case 1:

As an operator, I wish to add/remove repository configurations following an OpenAPI Validation Schema.

Use case 2:

As an operator, I wish to add/remove custom health checks following an OpenAPI Validation Schema.

Use case 3:

As an operator, I wish to configure ArgoCD  following an OpenAPI Validation Schema.