cfgen/main.go

package main

import (
	"errors"
	"flag"
	"fmt"
	"os"
	"text/template"

	"git.milar.in/milarin/adverr"
	"gopkg.in/yaml.v2"
)

var (
	ConfigFile = &Config{}
)

func main() {
	flag.Parse()

	if err := ReadConfigFile(); err != nil {
		fmt.Fprintln(os.Stderr, "no config file provided")
		os.Exit(1)
	}

	tmplMap, err := ParseTemplates(template.New("template"), ConfigFile.TemplateDir)
	if err != nil {
		adverr.Fatalln(err, 2)
	}

	if err := os.MkdirAll(ConfigFile.TargetDir, 0755); err != nil {
		adverr.Fatalln(ErrDirectoryCreationFailed.Wrap(err, ConfigFile.TargetDir), 3)
	}

	for _, tmpl := range tmplMap {
		if err := HandleTemplate(tmpl); err != nil {
			adverr.Fatalln(err, 4)
		}
	}
}

func ReadConfigFile() error {
	filename := flag.Arg(0)
	if filename == "" {
		return errors.New("no config file provided")
	}

	file, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	if err := yaml.NewDecoder(file).Decode(ConfigFile); err != nil {
		return err
	}

	ConfigFile.TemplateDir = os.ExpandEnv(ConfigFile.TemplateDir)
	ConfigFile.TargetDir = os.ExpandEnv(ConfigFile.TargetDir)
	RecursiveEnvLookupForMap(ConfigFile.Globals)

	return nil
}

func RecursiveEnvLookupForMap(m map[interface{}]interface{}) {
	for k, v := range m {
		if str, ok := v.(string); ok {
			m[k] = os.ExpandEnv(str)
		} else if m2, ok := v.(map[interface{}]interface{}); ok {
			RecursiveEnvLookupForMap(m2)
		} else if arr, ok := v.([]interface{}); ok {
			RecursiveEnvLookupForSlice(arr)
		}
	}
}

func RecursiveEnvLookupForSlice(s []interface{}) {
	for i, v := range s {
		if str, ok := v.(string); ok {
			s[i] = os.ExpandEnv(str)
		} else if m, ok := v.(map[interface{}]interface{}); ok {
			RecursiveEnvLookupForMap(m)
		} else if arr, ok := v.([]interface{}); ok {
			RecursiveEnvLookupForSlice(arr)
		}
	}
}