ruadan

ruadan

Environment Variable configuration with CLI flag override. Based on the amazing work of Kelsey Hightower's envconfig this aims to solve a similar problem with the addition of cli override flags for each part of your config. Currently you can configure everything with the tags of envconfig, envcli, json, and clidesc.

Note: Complex types are not supported yet and only basic, top level, arrays are set up

API Documentation

See godoc

Getting Started

$ go get github.com/bit-cmdr/ruadan

Example Usage

Predefined struct

package main

import (
  "log"
  "os"

  rd "github.com/bit-cmdr/ruadan"
)

type config struct {
  TestString string  `envconfig:"TEST_STRING"`
  TestInt    int     `envconfig:"TEST_INT" envcli:"testint"`
  TestFloat  float64 `envconfig:"TEST_FLOAT" envcli:"testfloat" clidesc:"set a float 64 value"`
  Pass       bool    `envcli:"pass"`
}

func main() {
  var cfg config

  fs, err := rd.GetConfigFlagSet(os.Args[1:], &cfg)
  if err != nil {
    log.Fatalf("Unable to configure:\n%v\n", err)
  }

  if !cfg.Pass {
    fs.PrintDefaults()
  }

  log.Printf("read so far:\n%+v\n", cfg)
}

Undefined struct method

package main

import (
  "log"
  "os"

  rd "github.com/bit-cmdr/ruadan"
)

func main() {
  cfg := rd.BuildConfig(
      rd.NewOptionString(
      "TestString", 
      rd.OptionENVName("TEST_STRING"), 
      rd.OptionCLIName("TEST_STRING"), 
      rd.OptionJSONName("testString"),
    ),
    rd.NewOptionInt(
      "TestInt", 
      rd.OptionENVName("TEST_INT"), 
      rd.OptionCLIName("testint"), 
      rd.OptionJSONName("testInt"),
    ),
    rd.NewOptionFloat(
      "TestFloat", 
      rd.OptionENVName("TEST_FLOAT"), 
      rd.OptionCLIName("testfloat"), 
      rd.OptionJSONName("testFloat"), 
      rd.OptionCLIUsage("set a float 64 value"),
    ),
    rd.NewOptionBool(
      "Pass", 
      rd.OptionENVName("PASS"), 
      rd.OptionCLIName("pass"), 
      rd.OptionJSONName("pass"),
    ),
  )
  
  // Note that the cfg.Config returned here is already a pointer, there's no need to pass by address
  fs, err := ruadan.GetConfigFlagSet(os.Args[1:], cfg.Config)
  if err != nil {
    log.Fatalf("Unable to configure:\n%v\n", err)
  }

  if !cfg.GetBool("Pass") {
    fs.PrintDefaults()
  }

  log.Printf("read so far:\n%+v\n", cfg)
}

Output for either method

$ go run main.go -pass
read so far:
{TestString: TestInt:0 TestFloat:0 Pass:true}

$ go run main.go -testint 1
  -TEST_STRING string
      flag: TEST_STRING or env: TEST_STRING
  -pass
      flag: pass or env: PASS
  -testfloat float
      set a float 64 value
  -testint int
      flag: testint or env: TEST_INT

read so far:
{TestString: TestInt:1 TestFloat:0 Pass:false}

$ go run main.go -TEST_STRING test
  -TEST_STRING string
      flag: TEST_STRING or env: TEST_STRING
  -pass
      flag: pass or env: PASS
  -testfloat float
      set a float 64 value
  -testint int
      flag: testint or env: TEST_INT

read so far:
{TestString:test TestInt:0 TestFloat:0 Pass:false}

$ PASS=true go run main.go -testint 5 -TEST_STRING testit -testfloat 3.14
read so far:
{TestString:testit TestInt:5 TestFloat:3.14 Pass:true}

Struct and Tags

type example struct {
    NoTags       int
    EnvConfig    int `envconfig:"EX_CONF"`
    EnvCliConfig int `envcli:"conf"`
    CliDesc      int `clidesc:"simple usage explanation"`
}

• NoTags will look for an env of NOTAGS and a cli of N0TAGS and have a description of flag: NOTAGS or env: NOTAGS
• EnvConfig will look for an env of EX_CONF and a cli of EX_CONF and have a description of flag: EX_CONF or env: EX_CONF
• EnvCliConfig will look for an env of CONF and a cli of conf and have a description of flag: conf or env: CONF
• CliDesc will look for an env of CLIDESC and a cli of CliDesc and have a description of simple usage explanation

It's meant to be as conventional as possible with the option to be incredibly specific

Build Config

cfg := rd.BuildConfig(
  rd.NewOptionBool(
    "Example",
    rd.OptionENVName("ENV_NAME")
    rd.OptionJSONName("jsonName")
    rd.OptionCLIName("cliflagname")
    rd.OptionCLIUsage("use this to describe how to use it from the cli")
  )
)

• NewOptionBool will add a new field to your struct. The first parameter is the name of the field, remember Go's naming conventions for exposing a field and capitalize the first letter. The rest of the Option fields are optional.
• OptionENVName is used to set the envconfig tag on the field
• OptionJSONName is used to set the json tag on the field
• OptionCLIName is used to set the envcli tag on the field
• OptionCLIUsage is used to set the clidesc tag on the field

In addition to NewOptionBool there is also

• NewOptionInt
• NewOptionString
• NewOptionFloat

There is also NewOptionComplex which takes a default value after the name argument in order to determine the underlying type, the value is not used. All of the NewOption... functions accept the same options, and their use is the same for all of them.