LearnCobra.md

Learn Cobra

• cobra + viper:

  • https://github.com/spf13/cobra
  • https://github.com/spf13/viper

• cobra generator:

  • https://github.com/spf13/cobra/blob/master/cobra/README.md Note: does not support go modules yet!

• tutorials

  • https://ordina-jworks.github.io/development/2018/10/20/make-your-own-cli-with-golang-and-cobra.html
  • https://github.com/nickgeudens/hello-cli
  • https://towardsdatascience.com/how-to-create-a-cli-in-golang-with-cobra-d729641c7177

basic concepts

e.g.: kubectl describe deployment <DEPLOYMENT_NAME> -o yaml

$ RootCommand Command SubCommand Args --Flags

("RootCommand" aka "AppName")

$ AppName Command Args --Flags

("Args" aka "positional arguments")

$ AppName Command SubCommand Args --Flags

("Flags" aka "named parameters/options")

In short ...

• Commands represent actions
• Args are things
• Flags are modifiers for those actions

e.g.: 
$ ./app say hello --name=Homer
$ ./app say hello --help

flags: local vs persistent flags

see: https://towardsdatascience.com/how-to-create-a-cli-in-golang-with-cobra-d729641c7177

• persistent flags: This flag will be available to the command it is assigned as well as all the child or subcommands of the command

e.g.: $ ./app say hello --help

• local flags: This flag is only available to the command which it is assigned to

e.g.: $ ./app say hello --name=Homer