Rename ENV var to TF_STATE

The old one is still supported.

README.md

@@ -20,10 +20,10 @@ add it, if you think that would be useful.
 ## Usage
 
 Ansible doesn't (seem to) support calling the inventory script with parameters,
-so you can specify the path to the state file using the `TI_TFSTATE` environment
+so you can specify the path to the state file using the `TF_STATE` environment
 variable, like so:
 
-	TI_TFSTATE=deploy/terraform.tfstate ansible-playbook --inventory-file=terraform-inventory deploy/playbook.yml
+	TF_STATE=deploy/terraform.tfstate ansible-playbook --inventory-file=terraform-inventory deploy/playbook.yml
 
 Alternately, you can create a little shell script and call that. Something like:
 

main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	env "github.com/danryan/env"
 	"os"
 	"path/filepath"
 )
@@ -12,52 +11,52 @@ var version = flag.Bool("version", false, "print version information and exit")
 var list = flag.Bool("list", false, "list mode")
 var host = flag.String("host", "", "host mode")
 
-type Config struct {
-	TfState string `env:"key=TI_TFSTATE"`
-}
-
 func main() {
 	flag.Parse()
 	file := flag.Arg(0)
-	cfg := &Config{}
-	env.MustProcess(cfg)
 
 	if *version == true {
 		fmt.Printf("%s version %s\n", os.Args[0], versionInfo())
 		return
 	}
 
+	// not given on the command line? try ENV.
 	if file == "" {
-		if cfg.TfState == "" {
-			fmt.Printf("Usage: %s [options] path\n", os.Args[0])
-			os.Exit(1)
-		} else {
-			file = cfg.TfState
-		}
+		file = os.Getenv("TF_STATE")
+	}
+
+	// also try the old ENV name.
+	if file == "" {
+		file = os.Getenv("TI_TFSTATE")
+	}
+
+	if file == "" {
+		fmt.Printf("Usage: %s [options] path\n", os.Args[0])
+		os.Exit(1)
 	}
 
 	if !*list && *host == "" {
-		fmt.Println("Either --host or --list must be specified")
+		fmt.Fprint(os.Stderr, "Either --host or --list must be specified")
 		os.Exit(1)
 	}
 
 	path, err := filepath.Abs(file)
 	if err != nil {
-		fmt.Printf("Invalid file: %s\n", err)
+		fmt.Fprintf(os.Stderr, "Invalid file: %s\n", err)
 		os.Exit(1)
 	}
 
 	stateFile, err := os.Open(path)
 	defer stateFile.Close()
 	if err != nil {
-		fmt.Printf("Error opening tfstate file: %s\n", err)
+		fmt.Fprintf(os.Stderr, "Error opening tfstate file: %s\n", err)
 		os.Exit(1)
 	}
 
 	var s state
 	err = s.read(stateFile)
 	if err != nil {
-		fmt.Printf("Error reading tfstate file: %s\n", err)
+		fmt.Fprintf(os.Stderr, "Error reading tfstate file: %s\n", err)
 		os.Exit(1)
 	}