Initial commit

envtmpl.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+)
+
+var (
+	ctx        *Context = &Context{Fallback: "", Envs: map[string]string{}}
+	inputPath  string   = ""
+	outputPath string   = ""
+)
+
+type Context struct {
+	Envs     map[string]string
+	Input    io.Reader
+	Output   io.Writer
+	Fallback string
+}
+
+func (c *Context) Fetch(arg string) string {
+	if c.Envs[arg] == "" {
+		return c.Fallback
+	}
+
+	return c.Envs[arg]
+}
+
+func (c *Context) Execute() {
+	tmpl := ""
+	scanner := bufio.NewScanner(c.Input)
+
+	for scanner.Scan() {
+		if tmpl == "" {
+			tmpl = scanner.Text()
+		} else {
+			tmpl += "\n" + scanner.Text()
+		}
+	}
+
+	t := template.New("envtmpl")
+
+	t.Parse(tmpl)
+
+	t.Execute(c.Output, c.Envs)
+}
+
+func init() {
+	flag.StringVar(&inputPath, "i", "", "Input template file path")
+	flag.StringVar(&inputPath, "input", "", "Input template file path")
+	flag.StringVar(&outputPath, "o", "", "Output path")
+	flag.StringVar(&outputPath, "output", "", "Output path")
+}
+
+func main() {
+	flag.Parse()
+
+	if inputPath != "" {
+		absInputPath, _ := filepath.Abs(inputPath)
+		input, err := os.OpenFile(absInputPath, os.O_RDONLY, 0666)
+
+		if err != nil {
+			panic(err.Error())
+		}
+		defer input.Close()
+
+		ctx.Input = input
+	} else {
+		ctx.Input = os.Stdin
+	}
+
+	if outputPath != "" {
+		absOutputPath, _ := filepath.Abs(outputPath)
+		output, err := os.OpenFile(absOutputPath, os.O_WRONLY|os.O_CREATE, 0666)
+
+		if err != nil {
+			panic(err.Error())
+		}
+		defer output.Close()
+
+		ctx.Output = output
+	} else {
+		ctx.Output = os.Stdout
+	}
+
+	for _, env := range os.Environ() {
+		r := strings.Split(env, "=")
+
+		if len(r) > 1 {
+			ctx.Envs[r[0]] = r[1]
+		}
+	}
+
+	ctx.Execute()
+}