cape

README

CLI

This module contains the code for adding commands to our CLI for the coordinator and client CLI.

Adding a new command

The first step to adding a command is familiarizing yourself with the CLI Style Guide. The style guide must be adhered to to the best of our abilities so that we have a great and consistent CLI experience.

When creating a new high level command, a new file should be created where the file name is the name of the command (e.g. cape update would result in a cmd/update.go file). All sub-commands can live in this file or be pulled out into other files as needed.

In each high-level file there will be init block that initializes the high-level command and any sub-commands. Once the commands are initialized the high-level command is append to the commands list which is then used by the cmd/root.go file to add the commands to the app.

func init() {
	startCmd := &cli.Command{
        ...
	}

	coordinatorCmd := &cli.Command{
        ...
		Subcommands: []*cli.Command{startCmd},
	}

	commands = append(commands, coordinatorCmd)
}

See cmd/coordinator.go to see a full example of our the above would look.

All flags should go in the cmd/flags.go file, all errors should go in the cmd/errors.go file, and arguments in cmd/arguments.go.

Implementing a new command

When you are implementing a command, you will declare a function that will be passed a *cli.Context variable. There are various middlewares and helpers that you can use to make writing a new command easy.

Accessing Flags

You can easily pull your flags off of the cli.Context. E.g. if you specified a port flag, you would access it with c.Int("port").

See cmd/flags.go for examples of declaring flags.

Accessing Arguments

Similarly, if you declared a URL argument named MyURLArgument, you could access it like so

URLValue, ok := Arguments(c.Context, MyURLArgument).(models.URL)

see cmd/arguments.go for examples on declaring arguments.

Communicating with the server

Through our middleware, you can easily get a reference to a client that can talk to the cape coordinator.

This can be done with

provider := GetProvider(c.Context)
client, err := provider.Client(c.Context)

Printing to the screen

One thing to note, is that your command should not ever directly print output. E.g. you should never write fmt.Printf. Instead, you should use the ui object. This will handle how to print what you want, where to print it based on user settings, and more.

Again, the UI is automatically provided to you via middleware. You can get access to it like so

provider := GetProvider(c.Context)
u := provider.UI(c.Context)

cmd/tokens.go has a good examples of different ways you can use the ui class.