Project layout for Go-based Operators

The operator-sdk CLI can generate, or scaffold, a number of packages and files for each Operator project.

Go-based project layout

Go-based Operator projects, the default type, generated using the operator-sdk init command contain the following files and directories:

File or directory	Purpose
`main.go`	Main program of the Operator. This instantiates a new manager that registers all custom resource definitions (CRDs) in the `apis/` directory and starts all controllers in the `controllers/` directory.
`apis/`	Directory tree that defines the APIs of the CRDs. You must edit the `apis/<version>/<kind>_types.go` files to define the API for each resource type and import these packages in your controllers to watch for these resource types.
`controllers/`	Controller implementations. Edit the `controller/<kind>_controller.go` files to define the reconcile logic of the controller for handling a resource type of the specified kind.
`config/`	Kubernetes manifests used to deploy your controller on a cluster, including CRDs, RBAC, and certificates.
`Makefile`	Targets used to build and deploy your controller.
`Dockerfile`	Instructions used by a container engine to build your Operator.
`manifests/`	Kubernetes manifests for registering CRDs, setting up RBAC, and deploying the Operator as a deployment.