In addition to custom flags, an application may register completely new commands. For example, to support alternative topologies or integrated automated acceptance tests as part of a CI/CD pipeline.
To register a custom command, define a new cobra.Command and add it to the sparta.CommandLineOptions.Root command value. Ensure you use the xxxxE Cobra functions so that errors can be properly propagated.
httpServerCommand := &cobra.Command{
Use: "httpServer",
Short: "Sample HelloWorld HTTP server",
Long: `Sample HelloWorld HTTP server that binds to port: ` + HTTPServerPort,
RunE: func(cmd *cobra.Command, args []string) error {
http.HandleFunc("/", helloWorldResource)
return http.ListenAndServe(fmt.Sprintf(":%d", HTTPServerPort), nil)
},
}
sparta.CommandLineOptions.Root.AddCommand(httpServerCommand)
Registering a user-defined command makes that command’s usage information seamlessly integrate with the standard commands:
$ go run main.go --help
Provision AWS Lambda and EC2 instance with same code
Usage:
main [command]
Available Commands:
delete Delete service
describe Describe service
execute Start the application and begin handling events
explore Interactively explore a provisioned service
help Help about any command
httpServer Sample HelloWorld HTTP server
profile Interactively examine service pprof output
provision Provision service
status Produce a report for a provisioned service
version Display version information
Flags:
-f, --format string Log format [text, json] (default "text")
-h, --help help for main
--ldflags string Go linker string definition flags (https://golang.org/cmd/link/)
-l, --level string Log level [panic, fatal, error, warn, info, debug] (default "info")
--nocolor Boolean flag to suppress colorized TTY output
-n, --noop Dry-run behavior only (do not perform mutations)
-t, --tags string Optional build tags for conditional compilation
-z, --timestamps Include UTC timestamp log line prefix
And you can query for user-command specific usage as in:
$ ./SpartaOmega httpServer --help
Custom command
Usage:
SpartaOmega httpServer [flags]
Global Flags:
-l, --level string Log level [panic, fatal, error, warn, info, debug] (default "info")
-n, --noop Dry-run behavior only (do not perform mutations)