feat: config supports variables

[IronCore864]

Summary

Key Points

• This is a breaking change.
• Documentation (new or existing) is updated.

Description

Config file now supports the use of variables.

• Use dtm --var-file to specify the location of the var file. Defaults to variables.yaml.
• If no --var-file is specified, and variables.yaml doesn't exist, continue without an error.

Related Issues

Related to #393 but not totally finished yet. Another PR of documentation with e2e test comes soon.

Screenshots

tiexin@mbp ~/work/stream $ ./dtm --debug apply -f config-variables.yaml
2022-04-14 15:40:43 ℹ [INFO]  Log level is: debug.
2022-04-14 15:40:43 ℹ [INFO]  Apply started.
2022-04-14 15:40:43 ℹ [DEBUG]  Original config:
tools:
- name: myapp
  plugin: gitlabci-generic
  options:
    pathWithNamespace: [[ gitlabUser ]]/go-hello-world
    branch: [[ defaultBranch ]]
    templateURL: [[ gitlabCIGolangTemplate ]]
    templateVariables:
      App: hello


2022-04-14 15:40:43 ℹ [DEBUG]  Variables file:
gitlabUser: ironcore864
defaultBranch: main
gitlabCIGolangTemplate: https://gitlab.com/ironcore864/go-hello-world/-/raw/main/go.tpl


2022-04-14 15:40:43 ℹ [DEBUG]  Config file after rendering with variables:
tools:
- name: myapp
  plugin: gitlabci-generic
  options:
    pathWithNamespace: ironcore864/go-hello-world
    branch: main
    templateURL: https://gitlab.com/ironcore864/go-hello-world/-/raw/main/go.tpl
    templateVariables:
      App: hello