From 571abd37009ae907e675f07628121667e184ab2f Mon Sep 17 00:00:00 2001
From: msshin <anarcher@gmail.com>
Date: Wed, 5 Aug 2015 16:30:41 +0900
Subject: [PATCH] Initial commit

---
 README.md | 28 +++++++++++++++++
 main.go   | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100644 README.md
 create mode 100644 main.go

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d47f0b7
--- /dev/null
+++ b/README.md
@@ -0,0 +1,28 @@
+# envconf
+
+It's simple env based config file transform for docker boot time configuration.
+
+
+```
+$cat a.conf
+[servera]
+HOST={{ .HOST | default "B" }}
+
+$export HOST="HOSTA"
+
+$envconf a.conf
+
+$cat a.conf
+```
+
+``` 
+$envconf a.conf b.conf ...
+or
+$export ENV_CONF_FILES=a.conf:b.conf:c.conf
+$envconf
+```
+
+
+
+
+
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..d89bf43
--- /dev/null
+++ b/main.go
@@ -0,0 +1,90 @@
+package main
+
+import (
+	"github.com/namsral/flag"
+	"log"
+	"os"
+	"strings"
+	"text/template"
+)
+
+const (
+	CONF_FILES = "ENV_CONF_FILES"
+)
+
+var (
+	env             map[string]string = make(map[string]string)
+	confPaths       []string
+	templateFuncMap template.FuncMap
+)
+
+func init() {
+	flag.Parse()
+
+	if len(flag.Args()) >= 0 {
+		for _, path := range flag.Args() {
+			confPaths = append(confPaths, path)
+		}
+	}
+
+	for _, pair := range os.Environ() {
+		item := strings.SplitN(pair, "=", 2)
+		if len(item) < 2 {
+			log.Fatalf("invalid item from os.Environ %s", pair)
+		}
+		env[item[0]] = item[1]
+	}
+
+	if val, ok := env[CONF_FILES]; ok {
+		paths := strings.Split(val, ":")
+		for _, path := range paths {
+			confPaths = append(confPaths, path)
+		}
+	}
+
+	templateFuncMap = template.FuncMap{
+		"default": func(args ...string) string {
+			return args[0]
+		},
+	}
+}
+
+func main() {
+	for _, path := range confPaths {
+		err := transformFile(path)
+		if err != nil {
+			log.Printf("Err: %s,%s", path, err)
+		} else {
+			log.Printf("Transformed %s", path)
+		}
+	}
+}
+
+func transformFile(path string) error {
+	t := template.New(path)
+	t = t.Funcs(templateFuncMap)
+	t, err := t.ParseFiles(path)
+	if err != nil {
+		log.Printf("Err: Parsing file %s %s", path, err)
+		return err
+	}
+
+	t = t.Funcs(templateFuncMap)
+
+	file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		log.Printf("Err: Can't open a file %s %s", path, err)
+		return err
+	}
+	defer func() {
+		if file != nil {
+			file.Close()
+		}
+	}()
+
+	if err = t.Execute(file, env); err != nil {
+		return err
+	}
+
+	return nil
+}