Feat: implement addon init command

[charlie0129]

Description of your changes

As described in #4116 (comment), this pr adds a vela addon init command.

• If the user provides all three Chart-related parameters, an addon scaffold, with a helm component inside, will be created.
• If the user does't provide all the necessary parameters to create a helm component, a basic addon scaffold is generated instead.

This pr does not close that issue, since more features are needed.

Command Help Text

$ vela addon init -h
Create an addon scaffold for quick starting. A Helm Component is generated if you provide Chart-related parameters.

Usage:
  vela addon init [flags]

Examples:
	vela addon init mongodb --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16
will create something like this:
	mongodb/
	├── definitions
	├── metadata.yaml
	├── readme.md
	├── resources
	│   └── mongodb.cue
	├── schemas
	└── template.yaml

If you want to store the scaffold in a different directory, you can use the -p/--path flag:
	vela addon init mongodb -p ./some/repo --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16

If you don't want the Helm component, just omit the three Chart-related parameters. We will create an empty scaffold for you.
	vela addon init mongodb

Flags:
      --chart string           Helm Chart name
      --helm-repo-url string   URL that points to a Helm repo
  -h, --help                   help for init
  -p, --path string            path to the addon directory (default is ./<addon-name>)
      --version string         version of the Chart

Global Flags:
  -y, --yes   Assume yes for all user prompts

Examples:

Normal creation

Only when ./<addon-name> (or user-specified path with -p) does not exist, or is an empty directory, will this command succeed. Otherwise, to prevent overwrites, this command will fail.

$ vela addon create mongodb --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16 -p mongo/addon
Scaffold created in directory mongo/addon. What to do next:
- Review and edit what we have generated in mongo/addon
- Check out our guide on how to build your own addon: https://kubevela.io/docs/platform-engineers/addon/intro
- To enable the addon, run: vela addon enable mongo/addon

File Structure and Contents (Helm Component)

$ vela addon init mongo-helm --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16
Scaffold created in directory mongo-helm. What to do next:
- Check out our guide on how to build your own addon: https://kubevela.io/docs/platform-engineers/addon/intro
- Review and edit what we have generated in mongo-helm
- To enable the addon, run: vela addon enable mongo-helm

$ tree mongo-helm
mongo-helm
├── definitions
├── metadata.yaml
├── readme.md
├── resources
│   └── mongo-helm.cue
├── schemas
└── template.yaml

3 directories, 4 files

$ cat mongo-helm/resources/mongo-helm.cue
output: {
	type: "helm"
	properties: {
		url:      "https://marketplace.azurecr.io/helm/v1/repo"
		repoType: "helm"
		chart:    "mongodb"
		version:  "12.1.16"
	}
}

$ cat mongo-helm/metadata.yaml
dependencies:
- name: fluxcd
description: An addon for KubeVela.
icon: ""
invisible: false
name: mongo-helm
tags:
- 12.1.16
version: 12.1.16

$ cat mongo-helm/readme.md
# Example mongo-helm Addon

Also check how to build your own addon: https://kubevela.net/docs/platform-engineers/addon/intro

## Directory Structure

- `template.yaml`: contains the basic app, you can add some component and workflow to meet your requirements. Other files in `resources/` and `definitions/` will be rendered as Components and appended in `spec.components`
- `metadata.yaml`: contains addon metadata information.
- `definitions/`: contains the X-Definition yaml/cue files. These file will be rendered as KubeVela Component in `template.yaml`
- `resources/`:
  - `parameter.cue` to expose parameters. It will be converted to JSON schema and rendered in UI forms.
  - All other files will be rendered as KubeVela Components. It can be one of the two types:
    - YAML file that contains only one resource. This will be rendered as a `raw` component
    - CUE template file that can read user input as `parameter.XXX` as defined `parameter.cue`.
      Basically the CUE template file will be combined with `parameter.cue` to render a resource.
      **You can specify the type and trait in this format**

$ cat mongo-helm/template.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  creationTimestamp: null
  name: mongo-helm
  namespace: vela-system
spec:
  components: null
status: {}

File Structure and Contents (Basic)

$ vela addon init mongo-sample
Scaffold created in directory mongo-sample. What to do next:
- Check out our guide on how to build your own addon: https://kubevela.io/docs/platform-engineers/addon/intro
- Review and edit what we have generated in mongo-sample
- To enable the addon, run: vela addon enable mongo-sample

$ tree mongo-sample
mongo-sample
├── definitions
├── metadata.yaml
├── readme.md
├── resources
├── schemas
└── template.yaml

3 directories, 3 files

$ cat mongo-sample/metadata.yaml
description: An addon for KubeVela.
icon: ""
invisible: false
name: mongo-sample
version: 1.0.0

$ cat mongo-sample/template.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  creationTimestamp: null
  name: mongo-sample
  namespace: vela-system
spec:
  components: null
status: {}

Directory already exists in local filesystem

If the directory is empty, it will behave the same as above.

$ vela addon init mongodb --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16
Error: directory mongodb is not empty. To avoid any data loss, manually delete it first

File with the same name already exists or other reasons

$ vela addon init main --helm-repo-url=https://marketplace.azurecr.io/helm/v1/repo --chart=mongodb --version=12.1.16
Error: we can't create directory main. Make sure the name has not already been taken and you have the proper rights to write to it

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Relevant unit tests have been added. Also manually tested several conditions described above.

Special notes for your reviewer

[codecov]

Codecov Report

Merging #4162 (61418c6) into master (f978519) will increase coverage by 0.03%.
The diff coverage is 78.16%.

@@            Coverage Diff             @@
##           master    #4162      +/-   ##
==========================================
+ Coverage   60.36%   60.39%   +0.03%     
==========================================
  Files         330      335       +5     
  Lines       31799    32540     +741     
==========================================
+ Hits        19195    19654     +459     
- Misses      10093    10330     +237     
- Partials     2511     2556      +45     

Flag	Coverage Δ
apiserver-unittests	34.59% <0.00%> (-0.84%)	⬇️
core-unittests	55.27% <78.16%> (+0.63%)	⬆️
e2e-multicluster-test	20.15% <0.00%> (+0.04%)	⬆️
e2e-rollout-tests	22.16% <0.00%> (-0.18%)	⬇️
e2etests	29.14% <0.00%> (-0.13%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/addon/create.go	78.04% <78.04%> (ø)
pkg/utils/file.go	62.16% <80.00%> (+6.60%)	⬆️
pkg/velaql/parse.go	65.67% <0.00%> (-26.00%)	⬇️
pkg/apiserver/domain/service/project.go	49.25% <0.00%> (-17.41%)	⬇️
pkg/workflow/hooks/data_passing.go	29.41% <0.00%> (-16.05%)	⬇️
pkg/apiserver/event/sync/cr2ux.go	44.77% <0.00%> (-15.23%)	⬇️
pkg/workflow/tasks/discover.go	68.93% <0.00%> (-13.95%)	⬇️
pkg/appfile/dryrun/dryrun.go	14.28% <0.00%> (-6.17%)	⬇️
pkg/resourcekeeper/resourcekeeper.go	69.69% <0.00%> (-4.50%)	⬇️
pkg/cue/definition/template.go	62.80% <0.00%> (-2.80%)	⬇️
... and 63 more

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[wangyikewxgm]

We can support a flag -p allow user to define the target path, default is ./

[charlie0129]

We can support a flag -p allow user to define the target path, default is ./

Yes, manually specifying path is supported. Just vela addon create ./some/path/to/addon-name, addon-name will be used as addon name.

kubevela/references/cli/addon.go

Line 379 in 7bd5e06

return fmt.Errorf("an addon name is required. You can specify a path. It will be used as the base directory for the addon")

[wangyikewxgm]

We can support a flag -p allow user to define the target path, default is ./

Yes, manually specifying path is supported. Just vela addon create ./some/path/to/addon-name, addon-name will be used as addon name.

kubevela/references/cli/addon.go

Line 379 in 7bd5e06

return fmt.Errorf("an addon name is required. You can specify a path. It will be used as the base directory for the addon")

IMO this is little bit tricky,

vela addon create name -p ./ 

Is better, and this is helm style.

[charlie0129]

Is better, and this is helm style.

Well, it is good to follow existing user habits. Will develop a -p option.

[wangyikewxgm]

Generally LGTM. Good job! Please fix the comments.

[wonderflow]

The empty scaffold should also create other addon dir for convenience, it's even better if we could put some meanful files as example in it.

https://kubevela.io/docs/platform-engineers/addon/intro#build-an-addon

[charlie0129]

Yes, there will be a minimal example in it (required files of an addon and other directories).

File Structure and Contents (Basic)

$ vela addon init mongo-sample
Scaffold created in directory mongo-sample. What to do next:
- Check out our guide on how to build your own addon: https://kubevela.io/docs/platform-engineers/addon/intro
- Review and edit what we have generated in mongo-sample
- To enable the addon, run: vela addon enable mongo-sample

$ tree mongo-sample
mongo-sample
├── definitions
├── metadata.yaml
├── readme.md
├── resources
├── schemas
└── template.yaml

3 directories, 3 files

$ cat mongo-sample/metadata.yaml
description: An addon for KubeVela.
icon: ""
invisible: false
name: mongo-sample
version: 1.0.0

$ cat mongo-sample/readme.md
# mongo-sample

Also check how to build your own addon: https://kubevela.net/docs/platform-engineers/addon/intro

## Directory Structure

- `template.yaml`: contains the basic app, you can add some component and workflow to meet your requirements. Other files in `resources/` and `definitions/` will be rendered as Components and appended in `spec.components`
- `metadata.yaml`: contains addon metadata information.
- `definitions/`: contains the X-Definition yaml/cue files. These file will be rendered as KubeVela Component in `template.yaml`
- `resources/`:
  - `parameter.cue` to expose parameters. It will be converted to JSON schema and rendered in UI forms.
  - All other files will be rendered as KubeVela Components. It can be one of the two types:
    - YAML file that contains only one resource. This will be rendered as a `raw` component
    - CUE template file that can read user input as `parameter.XXX` as defined `parameter.cue`.
      Basically the CUE template file will be combined with `parameter.cue` to render a resource.
      **You can specify the type and trait in this format**

$ cat mongo-sample/template.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  creationTimestamp: null
  name: mongo-sample
  namespace: vela-system
spec:
  components: null
status: {}

[wonderflow]

great

[wangyikewxgm]

great pr!

[Somefive]

Great Job!