README
¶
clap
Microservices oriented 12-factor Go library for parsing environment variables and command line flags to arbitrary config struct using struct tags to define default values and to override flag names and environment variables' names.
Example
package main
import (
"fmt"
"os"
"go.ectobit.com/clap"
)
func main() {
type config struct {
Port int `def:"3000"`
DB struct {
Kind clap.StringSlice `desc:"database kinds to use" def:"pg,mongo"`
Postgres struct {
Host string `flag:"pg-host" env:"PG_HOST" def:"localhost"`
Port string `flag:"pg-port" env:"PG_PORT" def:"5432"`
}
Mongo struct {
Host string `flag:"mongo-host" env:"MONGO_HOST" def:"mongodb://localhost:27017"`
}
}
}
cfg := &config{}
cmd := clap.New("myapp", os.Args[1:])
cmd.MustConfig(cfg)
}
Output of -help flag
Usage of myapp:
-db-kind value
database kinds to use (env MYAPP_DB_KIND) (default [pg mongo])
-mongo-host string
db mongo host (env MONGO_HOST) (default "mongodb://localhost:27017")
-pg-host string
db postgres host (env PG_HOST) (default "localhost")
-pg-port string
db postgres port (env PG_PORT) (default "5432")
-port int
port (env MYAPP_PORT) (default 3000)
Supported struct tags
- flag - override generated flag name
- env - override generated environment variable name
- desc - override generated flag description
- def - override default (zero) value
Custom flag types
- clap.StringSlice
- clap.IntSlice
- clap.URL
Order of precedence:
- command line options
- environment variables
- default values
TODO
- support req struct tag to mark required values
Origin of the name
This library is named the same as Rust's crate clap, but other than that there are not many similarities. Name clap fits very well to something used at the start.
Documentation
¶
Overview ¶
Package clap is a library for parsing command line flags in config struct using struct tags.
Example (Basic) ¶
package main
import (
"fmt"
"os"
"go.ectobit.com/clap"
)
func main() {
type config struct {
Host string
Port int
DB struct {
Kind string
Postgres struct {
Host string
}
Mongo struct {
Host clap.StringSlice
}
}
}
cfg := &config{}
cmd := clap.New("cool", os.Args[1:])
cmd.MustConfig(cfg)
fmt.Printf("Config:\n%#v\n", cfg)
}
Output:
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Clap ¶
type Clap struct {
// contains filtered or unexported fields
}
Clap is an abstraction of a CLI command.
func (*Clap) MustConfig ¶
func (c *Clap) MustConfig(config interface{})
MustConfig parses command line flags in supplied config struct using struct tags to optionally override generated environment variables' names, flags names, descriptions and default values.
func (*Clap) SetExit ¶ added in v0.2.1
SetExit overrides default exit function which uses os.Exit. Useful for testing.
type IntSlice ¶
type IntSlice []int
IntSlice implements flag.Getter interface for []int type.
func (*IntSlice) Set ¶
Set sets flag's value by splitting provided comma separated string.
type StringSlice ¶
type StringSlice []string
StringSlice implements flag.Getter interface for []string type.
func (*StringSlice) Set ¶
func (f *StringSlice) Set(s string) error
Set sets flag's value by splitting provided comma separated string.
type URL ¶
URL implements flag.Getter interface for url.URL type.
Source Files