recipe driven actions

[AmitKumarDas]

Thoughts 0

• kind Menu
  • Menu will be a K8s CR with a backing controller
  • Menu can list the Recipes that needs to be run
  • Menu can enable or disable one or more Recipe(s)
  • Menu is equivalent to test suite in testing world
  • NOTE: Menu is not necessarily tied to testing
• kind Recipe
  • Recipe will be a K8s CR with a backing controller
  • Recipe will consist of various actions that needs to be run
  • Recipe is equivalent to test case in testing world
  • NOTE: Recipe is not necessarily tied to testing
• Action
  • Action is not a K8s CR
  • An action can be any operation against a K8s resource
  • An action can be either of following:
  • create, apply, delete, assert, teardown, & more
  • When action is not backed by a K8s resource, we can have a jsonnet action
  • A jsonnet action can be an entire k8s controller in itself (refer MetaController)
  • NOTE: jsonnet action should solve the basic programming constructs only
  • NOTE: We should move from jsonnet action to specific K8s CustomResource eventually
• kind RecipeItem
  • RecipeItem will be a K8s CR without a backing controller
  • RecipeItem can consist of one or more Actions
  • RecipeItem can be referred to by one or more Recipe
  • RecipeItem will not have a backing controller
• kind RecipeValue
  • RecipeValue will be a K8s CR without a backing controller
  • RecipeValue can hold user values that can be used by jsonnet actions
  • RecipeValue can be used to store runtime values while executing jsonnet actions
  • RecipeValue can be used as a config to Recipe
• Assumptions
  • Pure declarative approach
  • No use of templating
  • No use of smart programming syntax
  • Use jsonnet i.e. (json that can embed code) when need for syntax arises
  • Actions of a Recipe can be run in parallel or serial
  • Use additional CR(s) & their backing controllers to make Recipe(s) easy
• Advantage:
  • Declarative intents should help in reducing the effort to build Recipes
  • No bash in yaml
  • No code in yaml
  • One can build a e2e test case in few minutes
  • One can build a install platform in few minutes

References

• Metacontroller

[AmitKumarDas]

NOTE: I have been merging initial code drops w.r.t recipe driven reconciliation. It is under controller/run & types/run.

Current Thought Process

• Should Run reconciler replicate attachments field of GenericController into its own spec
• Should Run reconciler list the attachments before invoking reconcile logic
• Should Run reconciler apply the attachments post invoking the reconcile logic
• Should Run reconciler invoke GenericController's controller code & reduce its GenericController to mere informer handler with updates to watch only
• Should Run reconciler either search for Run CR or Run config within the binary to execute the reconcile logic
• What should be considered to make things simple
• What should be considered to avoid dealing with multiple CRDs & CRs
• How should a user's CR delegate reconciliation to a Run resource where Run resource can either be a CR or a config within the binary.