update kubebuilder_v0_v1_difference.md

Author: Liujingfang1

docs/kubebuilder_v0_v1_difference.md

@@ -1,6 +1,9 @@
 # Kubebuilder v0 v.s. v1
 
-## command difference
+Kubebuilder 1.0 adds a new flag `--project-version`, it accepts two different values, `v0` and `v1`. When `v0` is used, the kubebuilder behavior and workflow is the same as kubebuilder 0.*. When `v1` is specified, the generated v1 project layout is architecturally different from v0 project. v1 project uses [controller-runtime](https://github.com/kubernetes-sigs/controller-runtime) set of libraries for controller implementation and used tools under [controller-tools](https://github.com/kubernetes-sigs/controller-tools) for scaffolding and generation. 
+
+
+## Command difference
   - kubebuilder v0 has `init`, `create controller`, `create resouece`, `create config`, `generate` commands and the workflow is
 
 ```
@@ -25,100 +28,28 @@
   make run
 ```
   In v1 project, there is no generate command. When the resource or controller is updated, users don't need to regenerate the project.
-  
-## scaffolding difference
-  Init a project with example.com and add a resource/api with group apps, version v1, kind Hello in both v0 and v1. The scaffolded projects are as follows.
-  - v0 project
-```
-.
-├── cmd
-│   └── controller-manager
-│       └── main.go
-├── Dockerfile.controller
-├── Gopkg.lock
-├── Gopkg.toml
-├── hack
-│   ├── boilerplate.go.txt
-│   ├── doc.go
-│   ├── imports.go
-│   └── sample
-│       └── hello.yaml
-├── pkg
-│   ├── apis
-│   │   ├── apps
-│   │   │   ├── doc.go
-│   │   │   └── v1
-│   │   └── doc.go
-│   ├── client
-│   │   ├── clientset
-│   │   │   └── versioned
-│   │   ├── informers
-│   │   │   └── externalversions
-│   │   └── listers
-│   │       └── apps
-│   ├── controller
-│   │   ├── doc.go
-│   │   └── hello
-│   │       ├── controller.go
-│   │       ├── controller_test.go
-│   │       └── hello_suite_test.go
-│   ├── doc.go
-│   └── inject
-│       ├── args
-│       │   └── args.go
-│       ├── doc.go
-│       ├── inject.go
-│       └── zz_generated.kubebuilder.go
-└── vendor
 
-```
-  - v1 project
-```
-├── cmd
-│   └── manager
-│       └── main.go
-├── config
-│   ├── crds
-│   │   └── apps_v1_hello.yaml
-│   └── manager
-│       ├── apps_rolebinding_rbac.yaml
-│       ├── apps_role_rbac.yaml
-│       └── manager.yaml
-├── Dockerfile
-├── Gopkg.toml
-├── hack
-│   └── boilerplate.go.txt
-├── Makefile
-├── pkg
-│   ├── apis
-│   │   ├── addtoscheme_apps_v1.go
-│   │   ├── apis.go
-│   │   └── apps
-│   │       ├── group.go
-│   │       └── v1
-│   │           ├── doc.go
-│   │           ├── hello_types.go
-│   │           ├── hello_types_test.go
-│   │           ├── register.go
-│   │           └── v1_suite_test.go
-│   └── controller
-│       ├── add_hello.go
-│       ├── controller.go
-│       └── hello
-│           ├── hello_controller.go
-│           ├── hello_controller_suite_test.go
-│           └── hello_controller_test.go
-├── PROJECT
-└── vendor
-```
-Compared with v0 project, there is no `client`, `inject` folders.
+## Scaffolding difference
+
+- v0 project contains a directory pkg/client while v1 project doesn't
+- v0 project contains a directory inject while v1 project doesn't
+- v0 project layout follows predefined directory layout `pkg/apis` and `pkg/controller` while v1 project accepts user specified path
+- In v1 project, there is a `init()` function for every api and controller.
+
+  
+## Library difference
+### Controller libraries
+  - v0 projects import the controller library from kubebuilder `kubebuilder/pkg/controller`. It provides a `GenericController` type with a list of functions. 
 
-## library difference
+  - v1 projects import the controller libraries from controller-runtime, such as `controller-runtime/pkg/controller`, `controller-runtime/pkg/reconcile`.
 
-  - v0 projects import the libraries from kubebuilder, for example kubebuilder/pkg/controller. It provides a `GenericController` type with a list of functions. Note that for created resources, the corresponding client library is generated under the project folder `pkg/client`
+### Client libraries
 
-  - v1 projects import the libraries from controller-runtime, for example controller-runtime/pkg/controller, controller-runtime/pkg/client, controller-runtime/pkg/reconcile. Note that for created resources or core types, the client library is provided by controller-runtime.
+  - In v0 projects, the client libraries is generated by `kubebuilder generate` under directory `pkg/client` and imported wherever they are used in the project.
 
-## wiring difference
+  - v1 projects imports the dynamic client library from controller-runtime `controller-runtime/pkg/client`.
+    
+## Wiring difference
+Wiring refers to the machanics of integrating controllers to controller-manager and injecting the dependencies in them. 
   - v0 projects has a `inject` package and it provides functions for adding the controller to controller-manager as well as registering CRDs.
   - v1 projects doesn't have a `inject` package, the controller is added to controller-manager by a `init` function inside add_<type>.go file inside the controller directory. The types is registered by a `init` function inside <type>_types.go file inside the apis directory.