Initial version of rconfig

2024-11-09 16:30:04 +00:00 · 2015-07-12 11:51:19 +02:00 · 2015-07-12 11:51:19 +02:00 · 0c78105a26
commit 0c78105a26
5 changed files with 664 additions and 0 deletions
--- a/13
+++ b/13
@ -0,0 +1,13 @@
+Copyright 2015 Knut Ahlers <knut@ahlers.me>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
--- a/README.md
+++ b/README.md
@ -0,0 +1,58 @@
+[![Circle CI](https://circleci.com/gh/Luzifer/rconfig.svg?style=svg)](https://circleci.com/gh/Luzifer/rconfig)
+[![License: Apache v2.0](https://badge.luzifer.io/v1/badge?color=5d79b5&title=license&text=Apache+v2.0)](http://www.apache.org/licenses/LICENSE-2.0)
+[![Documentation](https://badge.luzifer.io/v1/badge?title=godoc&text=reference)](https://godoc.org/github.com/Luzifer/rconfig)
+
+## Description
+
+> Package rconfig implements a CLI configuration reader with struct-embedded defaults, environment variables and posix compatible flag parsing using the [pflag](https://github.com/spf13/pflag) library.
+
+## Installation
+
+Install by running:
+
+```
+go get -u github.com/Luzifer/rconfig
+```
+
+Run tests by running:
+
+```
+go test -v -race -cover github.com/Luzifer/rconfig
+```
+
+## Usage
+
+As a first step define a struct holding your configuration:
+
+```go
+type config struct {
+  Username string `default:"unknown" flag:"user" description:"Your name"`
+  Details  struct {
+    Age int `default:"25" flag:"age" env:"age" description:"Your age"`
+  }
+}
+```
+
+Next create an instance of that struct and let `rconfig` fill that config:
+
+```go
+var cfg config
+func init() {
+  cfg = config{}
+  rconfig.Parse(&cfg)
+}
+```
+
+You're ready to access your configuration:
+
+```go
+func main() {
+  fmt.Printf("Hello %s, happy birthday for your %dth birthday.",
+		cfg.Username,
+		cfg.Details.Age)
+}
+```
+
+## More info
+
+You can see the full reference documentation of the rconfig package [at godoc.org](https://godoc.org/github.com/Luzifer/rconfig), or through go's standard documentation system by running `godoc -http=:6060` and browsing to [http://localhost:6060/pkg/github.com/Luzifer/rconfig](http://localhost:6060/pkg/github.com/Luzifer/rconfig) after installation.
--- a/config.go
+++ b/config.go
@ -0,0 +1,282 @@
+// Package rconfig implements a CLI configuration reader with struct-embedded
+// defaults, environment variables and posix compatible flag parsing using
+// the pflag library.
+package rconfig //import "github.com/Luzifer/rconfig"
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"github.com/spf13/pflag"
+)
+
+var fs *pflag.FlagSet
+
+// Parse takes the pointer to a struct filled with variables which should be read
+// from ENV, default or flag. The precedence in this is flag > ENV > default. So
+// if a flag is specified on the CLI it will overwrite the ENV and otherwise ENV
+// overwrites the default specified.
+//
+// For your configuration struct you can use the following struct-tags to control
+// the behavior of rconfig:
+//
+//     default: Set a default value
+//     env: Read the value from this environment variable
+//     flag: Flag to read in format "long,short" (for example "listen,l")
+//     description: A help text for Usage output to guide your users
+//
+// The format you need to specify those values you can see in the example to this
+// function.
+//
+func Parse(config interface{}) error {
+	return parse(config, nil)
+}
+
+// Usage prints a basic usage with the corresponding defaults for the flags to
+// os.Stdout. The defaults are derived from the `default` struct-tag and the ENV.
+func Usage() {
+	if fs != nil && fs.Parsed() {
+		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
+		fs.PrintDefaults()
+	}
+}
+
+func parse(in interface{}, args []string) error {
+	if args == nil {
+		args = os.Args
+	}
+
+	fs = pflag.NewFlagSet(os.Args[0], pflag.ExitOnError)
+	if err := execTags(in, fs); err != nil {
+		return err
+	}
+
+	return fs.Parse(args)
+}
+
+func execTags(in interface{}, fs *pflag.FlagSet) error {
+	if reflect.TypeOf(in).Kind() != reflect.Ptr {
+		return errors.New("Calling parser with non-pointer")
+	}
+
+	if reflect.ValueOf(in).Elem().Kind() != reflect.Struct {
+		return errors.New("Calling parser with pointer to non-struct")
+	}
+
+	st := reflect.ValueOf(in).Elem()
+	for i := 0; i < st.NumField(); i++ {
+		valField := st.Field(i)
+		typeField := st.Type().Field(i)
+
+		if typeField.Tag.Get("default") == "" && typeField.Tag.Get("env") == "" && typeField.Tag.Get("flag") == "" && typeField.Type.Kind() != reflect.Struct {
+			// None of our supported tags is present and it's not a sub-struct
+			continue
+		}
+
+		value := envDefault(typeField.Tag.Get("env"), typeField.Tag.Get("default"))
+		parts := strings.Split(typeField.Tag.Get("flag"), ",")
+
+		switch typeField.Type.Kind() {
+		case reflect.String:
+			if typeField.Tag.Get("flag") != "" {
+				if len(parts) == 1 {
+					fs.StringVar(valField.Addr().Interface().(*string), parts[0], value, typeField.Tag.Get("description"))
+				} else {
+					fs.StringVarP(valField.Addr().Interface().(*string), parts[0], parts[1], value, typeField.Tag.Get("description"))
+				}
+			} else {
+				valField.SetString(value)
+			}
+
+		case reflect.Bool:
+			v := value == "true"
+			if typeField.Tag.Get("flag") != "" {
+				if len(parts) == 1 {
+					fs.BoolVar(valField.Addr().Interface().(*bool), parts[0], v, typeField.Tag.Get("description"))
+				} else {
+					fs.BoolVarP(valField.Addr().Interface().(*bool), parts[0], parts[1], v, typeField.Tag.Get("description"))
+				}
+			} else {
+				valField.SetBool(v)
+			}
+
+		case reflect.Int, reflect.Int8, reflect.Int32, reflect.Int64:
+			vt, err := strconv.ParseInt(value, 10, 64)
+			if err != nil {
+				if value == "" {
+					vt = 0
+				} else {
+					return err
+				}
+			}
+			if typeField.Tag.Get("flag") != "" {
+				registerFlagInt(typeField.Type.Kind(), fs, valField.Addr().Interface(), parts, vt, typeField.Tag.Get("description"))
+			} else {
+				valField.SetInt(vt)
+			}
+
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			vt, err := strconv.ParseUint(value, 10, 64)
+			if err != nil {
+				if value == "" {
+					vt = 0
+				} else {
+					return err
+				}
+			}
+			if typeField.Tag.Get("flag") != "" {
+				registerFlagUint(typeField.Type.Kind(), fs, valField.Addr().Interface(), parts, vt, typeField.Tag.Get("description"))
+			} else {
+				valField.SetUint(vt)
+			}
+
+		case reflect.Float32, reflect.Float64:
+			vt, err := strconv.ParseFloat(value, 64)
+			if err != nil {
+				if value == "" {
+					vt = 0.0
+				} else {
+					return err
+				}
+			}
+			if typeField.Tag.Get("flag") != "" {
+				registerFlagFloat(typeField.Type.Kind(), fs, valField.Addr().Interface(), parts, vt, typeField.Tag.Get("description"))
+			} else {
+				valField.SetFloat(vt)
+			}
+
+		case reflect.Struct:
+			if err := execTags(valField.Addr().Interface(), fs); err != nil {
+				return err
+			}
+
+		case reflect.Slice:
+			switch typeField.Type.Elem().Kind() {
+			case reflect.Int:
+				def := []int{}
+				for _, v := range strings.Split(value, ",") {
+					it, err := strconv.ParseInt(strings.TrimSpace(v), 10, 64)
+					if err != nil {
+						return err
+					}
+					def = append(def, int(it))
+				}
+				if len(parts) == 1 {
+					fs.IntSliceVar(valField.Addr().Interface().(*[]int), parts[0], def, typeField.Tag.Get("description"))
+				} else {
+					fs.IntSliceVarP(valField.Addr().Interface().(*[]int), parts[0], parts[1], def, typeField.Tag.Get("description"))
+				}
+			case reflect.String:
+				del := typeField.Tag.Get("delimiter")
+				if len(del) == 0 {
+					del = ","
+				}
+				def := strings.Split(value, del)
+				if len(parts) == 1 {
+					fs.StringSliceVar(valField.Addr().Interface().(*[]string), parts[0], def, typeField.Tag.Get("description"))
+				} else {
+					fs.StringSliceVarP(valField.Addr().Interface().(*[]string), parts[0], parts[1], def, typeField.Tag.Get("description"))
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+func registerFlagFloat(t reflect.Kind, fs *pflag.FlagSet, field interface{}, parts []string, vt float64, desc string) {
+	switch t {
+	case reflect.Float32:
+		if len(parts) == 1 {
+			fs.Float32Var(field.(*float32), parts[0], float32(vt), desc)
+		} else {
+			fs.Float32VarP(field.(*float32), parts[0], parts[1], float32(vt), desc)
+		}
+	case reflect.Float64:
+		if len(parts) == 1 {
+			fs.Float64Var(field.(*float64), parts[0], float64(vt), desc)
+		} else {
+			fs.Float64VarP(field.(*float64), parts[0], parts[1], float64(vt), desc)
+		}
+	}
+}
+
+func registerFlagInt(t reflect.Kind, fs *pflag.FlagSet, field interface{}, parts []string, vt int64, desc string) {
+	switch t {
+	case reflect.Int:
+		if len(parts) == 1 {
+			fs.IntVar(field.(*int), parts[0], int(vt), desc)
+		} else {
+			fs.IntVarP(field.(*int), parts[0], parts[1], int(vt), desc)
+		}
+	case reflect.Int8:
+		if len(parts) == 1 {
+			fs.Int8Var(field.(*int8), parts[0], int8(vt), desc)
+		} else {
+			fs.Int8VarP(field.(*int8), parts[0], parts[1], int8(vt), desc)
+		}
+	case reflect.Int32:
+		if len(parts) == 1 {
+			fs.Int32Var(field.(*int32), parts[0], int32(vt), desc)
+		} else {
+			fs.Int32VarP(field.(*int32), parts[0], parts[1], int32(vt), desc)
+		}
+	case reflect.Int64:
+		if len(parts) == 1 {
+			fs.Int64Var(field.(*int64), parts[0], int64(vt), desc)
+		} else {
+			fs.Int64VarP(field.(*int64), parts[0], parts[1], int64(vt), desc)
+		}
+	}
+}
+
+func registerFlagUint(t reflect.Kind, fs *pflag.FlagSet, field interface{}, parts []string, vt uint64, desc string) {
+	switch t {
+	case reflect.Uint:
+		if len(parts) == 1 {
+			fs.UintVar(field.(*uint), parts[0], uint(vt), desc)
+		} else {
+			fs.UintVarP(field.(*uint), parts[0], parts[1], uint(vt), desc)
+		}
+	case reflect.Uint8:
+		if len(parts) == 1 {
+			fs.Uint8Var(field.(*uint8), parts[0], uint8(vt), desc)
+		} else {
+			fs.Uint8VarP(field.(*uint8), parts[0], parts[1], uint8(vt), desc)
+		}
+	case reflect.Uint16:
+		if len(parts) == 1 {
+			fs.Uint16Var(field.(*uint16), parts[0], uint16(vt), desc)
+		} else {
+			fs.Uint16VarP(field.(*uint16), parts[0], parts[1], uint16(vt), desc)
+		}
+	case reflect.Uint32:
+		if len(parts) == 1 {
+			fs.Uint32Var(field.(*uint32), parts[0], uint32(vt), desc)
+		} else {
+			fs.Uint32VarP(field.(*uint32), parts[0], parts[1], uint32(vt), desc)
+		}
+	case reflect.Uint64:
+		if len(parts) == 1 {
+			fs.Uint64Var(field.(*uint64), parts[0], uint64(vt), desc)
+		} else {
+			fs.Uint64VarP(field.(*uint64), parts[0], parts[1], uint64(vt), desc)
+		}
+	}
+}
+
+func envDefault(env, def string) string {
+	value := def
+
+	if env != "" {
+		if e := os.Getenv(env); e != "" {
+			value = e
+		}
+	}
+
+	return value
+}
--- a/config_test.go
+++ b/config_test.go
@ -0,0 +1,274 @@
+package rconfig
+
+import (
+	"os"
+	"testing"
+)
+
+func TestGeneralMechanics(t *testing.T) {
+	cfg := struct {
+		Test        string `default:"foo" env:"shell" flag:"shell" description:"Test"`
+		Test2       string `default:"blub" env:"testvar" flag:"testvar,t" description:"Test"`
+		DefaultFlag string `default:"goo"`
+		SadFlag     string
+	}{}
+
+	parse(&cfg, []string{
+		"--shell=test23",
+		"-t", "bla",
+	})
+
+	if cfg.Test != "test23" {
+		t.Errorf("Test should be 'test23', is '%s'", cfg.Test)
+	}
+
+	if cfg.Test2 != "bla" {
+		t.Errorf("Test2 should be 'bla', is '%s'", cfg.Test2)
+	}
+
+	if cfg.SadFlag != "" {
+		t.Errorf("SadFlag should be '', is '%s'", cfg.SadFlag)
+	}
+
+	if cfg.DefaultFlag != "goo" {
+		t.Errorf("DefaultFlag should be 'goo', is '%s'", cfg.DefaultFlag)
+	}
+
+	parse(&cfg, []string{})
+
+	if cfg.Test != "foo" {
+		t.Errorf("Test should be 'foo', is '%s'", cfg.Test)
+	}
+
+	os.Setenv("shell", "test546")
+	parse(&cfg, []string{})
+
+	if cfg.Test != "test546" {
+		t.Errorf("Test should be 'test546', is '%s'", cfg.Test)
+	}
+}
+
+func TestBool(t *testing.T) {
+	cfg := struct {
+		Test1 bool `default:"true"`
+		Test2 bool `default:"false" flag:"test2"`
+		Test3 bool `default:"true" flag:"test3,t"`
+		Test4 bool `flag:"test4"`
+	}{}
+
+	parse(&cfg, []string{
+		"--test2",
+		"-t",
+	})
+
+	if !cfg.Test1 {
+		t.Errorf("Test1 should be 'true', is '%+v'", cfg.Test1)
+	}
+	if !cfg.Test2 {
+		t.Errorf("Test1 should be 'true', is '%+v'", cfg.Test2)
+	}
+	if !cfg.Test3 {
+		t.Errorf("Test1 should be 'true', is '%+v'", cfg.Test3)
+	}
+	if cfg.Test4 {
+		t.Errorf("Test1 should be 'false', is '%+v'", cfg.Test3)
+	}
+}
+
+func TestInt(t *testing.T) {
+	cfg := struct {
+		Test    int   `flag:"int"`
+		TestP   int   `flag:"intp,i"`
+		Test8   int8  `flag:"int8"`
+		Test8P  int8  `flag:"int8p,8"`
+		Test32  int32 `flag:"int32"`
+		Test32P int32 `flag:"int32p,3"`
+		Test64  int64 `flag:"int64"`
+		Test64P int64 `flag:"int64p,6"`
+		TestDef int8  `default:"66"`
+	}{}
+
+	parse(&cfg, []string{
+		"--int=1", "-i", "2",
+		"--int8=3", "-8", "4",
+		"--int32=5", "-3", "6",
+		"--int64=7", "-6", "8",
+	})
+
+	if cfg.Test != 1 || cfg.TestP != 2 || cfg.Test8 != 3 || cfg.Test8P != 4 || cfg.Test32 != 5 || cfg.Test32P != 6 || cfg.Test64 != 7 || cfg.Test64P != 8 {
+		t.Errorf("One of the int tests failed.")
+	}
+
+	if cfg.TestDef != 66 {
+		t.Errorf("TestDef should be '66', is '%d'", cfg.TestDef)
+	}
+}
+
+func TestUint(t *testing.T) {
+	cfg := struct {
+		Test    uint   `flag:"int"`
+		TestP   uint   `flag:"intp,i"`
+		Test8   uint8  `flag:"int8"`
+		Test8P  uint8  `flag:"int8p,8"`
+		Test16  uint16 `flag:"int16"`
+		Test16P uint16 `flag:"int16p,1"`
+		Test32  uint32 `flag:"int32"`
+		Test32P uint32 `flag:"int32p,3"`
+		Test64  uint64 `flag:"int64"`
+		Test64P uint64 `flag:"int64p,6"`
+		TestDef uint8  `default:"66"`
+	}{}
+
+	parse(&cfg, []string{
+		"--int=1", "-i", "2",
+		"--int8=3", "-8", "4",
+		"--int32=5", "-3", "6",
+		"--int64=7", "-6", "8",
+		"--int16=9", "-1", "10",
+	})
+
+	if cfg.Test != 1 || cfg.TestP != 2 || cfg.Test8 != 3 || cfg.Test8P != 4 || cfg.Test32 != 5 || cfg.Test32P != 6 || cfg.Test64 != 7 || cfg.Test64P != 8 || cfg.Test16 != 9 || cfg.Test16P != 10 {
+		t.Errorf("One of the uint tests failed.")
+	}
+
+	if cfg.TestDef != 66 {
+		t.Errorf("TestDef should be '66', is '%d'", cfg.TestDef)
+	}
+}
+
+func TestFloat(t *testing.T) {
+	cfg := struct {
+		Test32  float32 `flag:"float32"`
+		Test32P float32 `flag:"float32p,3"`
+		Test64  float64 `flag:"float64"`
+		Test64P float64 `flag:"float64p,6"`
+		TestDef float32 `default:"66.256"`
+	}{}
+
+	parse(&cfg, []string{
+		"--float32=5.5", "-3", "6.6",
+		"--float64=7.7", "-6", "8.8",
+	})
+
+	if cfg.Test32 != 5.5 || cfg.Test32P != 6.6 || cfg.Test64 != 7.7 || cfg.Test64P != 8.8 {
+		t.Errorf("One of the int tests failed.")
+	}
+
+	if cfg.TestDef != 66.256 {
+		t.Errorf("TestDef should be '66.256', is '%.3f'", cfg.TestDef)
+	}
+}
+
+func TestSubStruct(t *testing.T) {
+	cfg := struct {
+		Test string `default:"blubb"`
+		Sub  struct {
+			Test string `default:"Hallo"`
+		}
+	}{}
+
+	if err := parse(&cfg, []string{}); err != nil {
+		t.Errorf("Test errored: %s", err)
+	}
+
+	if cfg.Test != "blubb" {
+		t.Errorf("Test should be 'blubb', is '%s'", cfg.Test)
+	}
+
+	if cfg.Sub.Test != "Hallo" {
+		t.Errorf("Sub.Test should be 'Hallo', is '%s'", cfg.Sub.Test)
+	}
+}
+
+func TestSlice(t *testing.T) {
+	cfg := struct {
+		Int     []int    `default:"1,2,3" flag:"int"`
+		String  []string `default:"a,b,c" flag:"string"`
+		IntP    []int    `default:"1,2,3" flag:"intp,i"`
+		StringP []string `default:"a,b,c" flag:"stringp,s"`
+	}{}
+
+	if err := parse(&cfg, []string{
+		"--int=4,5", "-s", "hallo,welt",
+	}); err != nil {
+		t.Errorf("Test errored: %s", err)
+	}
+
+	if len(cfg.Int) != 2 || cfg.Int[0] != 4 || cfg.Int[1] != 5 {
+		t.Errorf("Int should be '4,5', is '%+v'", cfg.Int)
+	}
+
+	if len(cfg.String) != 3 || cfg.String[0] != "a" || cfg.String[1] != "b" {
+		t.Errorf("String should be 'a,b,c', is '%+v'", cfg.String)
+	}
+
+	if len(cfg.StringP) != 2 || cfg.StringP[0] != "hallo" || cfg.StringP[1] != "welt" {
+		t.Errorf("StringP should be 'hallo,welt', is '%+v'", cfg.StringP)
+	}
+}
+
+func TestErrors(t *testing.T) {
+	if err := parse(&struct {
+		A int `default:"a"`
+	}{}, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+
+	if err := parse(&struct {
+		A float32 `default:"a"`
+	}{}, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+
+	if err := parse(&struct {
+		A uint `default:"a"`
+	}{}, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+
+	if err := parse(&struct {
+		B struct {
+			A uint `default:"a"`
+		}
+	}{}, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+
+	if err := parse(&struct {
+		A []int `default:"a,bn"`
+	}{}, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+}
+
+func TestOSArgs(t *testing.T) {
+	os.Args = []string{"--a=bar"}
+
+	cfg := struct {
+		A string `default:"a" flag:"a"`
+	}{}
+
+	Parse(&cfg)
+
+	if cfg.A != "bar" {
+		t.Errorf("A should be 'bar', is '%s'", cfg.A)
+	}
+}
+
+func TestNonPointer(t *testing.T) {
+	cfg := struct {
+		A string `default:"a"`
+	}{}
+
+	if err := parse(cfg, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+}
+
+func TestOtherType(t *testing.T) {
+	cfg := "test"
+
+	if err := parse(&cfg, []string{}); err == nil {
+		t.Errorf("Test should have errored")
+	}
+}
--- a/example_test.go
+++ b/example_test.go
@ -0,0 +1,37 @@
+package rconfig
+
+import (
+	"fmt"
+	"os"
+)
+
+func ExampleParse() {
+	// We're building an example configuration with a sub-struct to be filled
+	// by the Parse command.
+	config := struct {
+		Username string `default:"unknown" flag:"user,u" description:"Your name"`
+		Details  struct {
+			Age int `default:"25" flag:"age" description:"Your age"`
+		}
+	}{}
+
+	// To have more relieable results we're setting os.Args to a known value.
+	// In real-life use cases you wouldn't do this but parse the original
+	// commandline arguments.
+	os.Args = []string{
+		"example",
+		"--user=Luzifer",
+	}
+
+	Parse(&config)
+
+	fmt.Printf("Hello %s, happy birthday for your %dth birthday.",
+		config.Username,
+		config.Details.Age)
+
+	// You can also show an usage message for your user
+	Usage()
+
+	// Output:
+	// Hello Luzifer, happy birthday for your 25th birthday.
+}