main.go

/*******************************************************************************
*
* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*
*******************************************************************************/

package main

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"text/template"

	"github.com/BurntSushi/toml"
	"github.com/MasterMinds/sprig"
)

const defaultInputs = `/etc/replicator.d/*.toml`

func failIf(err error) {
	if err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
		os.Exit(1)
	}
}

func readConfig(globs string) map[string]interface{} {
	var paths []string
	for _, glob := range filepath.SplitList(globs) {
		globPaths, err := filepath.Glob(glob)
		failIf(err)
		if len(globPaths) == 0 {
			failIf(fmt.Errorf("no matches for glob: %s", glob))
		}
		paths = append(paths, globPaths...)
	}

	result := map[string]interface{}{}
	for _, path := range paths {
		bytes, err := ioutil.ReadFile(path)
		failIf(err)
		var next map[string]interface{}
		failIf(toml.Unmarshal(bytes, &next))
		result, err = MergeTables(result, next)
		failIf(err)
	}

	return result
}

func main() {
	inputs := os.Getenv("REPLICATOR_INPUTS")
	if inputs == "" {
		inputs = defaultInputs
	}

	var locals struct {
		Vars map[string]interface{}
	}
	locals.Vars = readConfig(inputs)

	tmplText, err := ioutil.ReadAll(os.Stdin)
	failIf(err)
	tmpl, err := template.New("stdin").Funcs(sprig.TxtFuncMap()).Funcs(customFuncMap()).Parse(string(tmplText))
	failIf(err)
	failIf(tmpl.Execute(os.Stdout, &locals))
}

func customFuncMap() template.FuncMap {
	return template.FuncMap{
		"toToml": toToml,
	}
}
func toToml(val interface{}) (string, error) {
	var buf bytes.Buffer
	err := toml.NewEncoder(&buf).Encode(val)
	return buf.String(), err
}