documentation updates and tweaking workflows with env vars. It now throws errors if they're not set

README.md

@@ -29,6 +29,9 @@ charts:
     set:                                 # values (--set)
       - name: address
         value: https://vault.example.com
+    env:                                 # values (--set) but value will be pulled from environment variables. Will throw an error if the environment variable is not set.
+      - name: db.password
+        value: DB_PASSWORD               # $DB_PASSOWRD needs to be set in the calling environment ex: export DB_PASSWORD='password1'
 
 ```
 
@@ -41,24 +44,24 @@ charts:
 
 ```
 NAME:
-   helmfile
+   helmfile -
 
 USAGE:
-   helmfile [global options] command [command options] [arguments...]
+   main [global options] command [command options] [arguments...]
 
 VERSION:
-   0.0.0
+   0.1.0
 
 COMMANDS:
-     repos    sync repositories from state file (helm repo add && help repo update)
-     charts   sync charts from state file (helm repo upgrade --install)
-     sync     sync all resources from state file (repos && charts)
-     delete   delete charts from state file (helm delete)
-     help, h  Shows a list of commands or help for one command
+     repos   sync repositories from state file (helm repo add && helm repo update)
+     charts  sync charts from state file (helm repo upgrade --install)
+     sync    sync all resources from state file (repos && charts)
+     delete  delete charts from state file (helm delete)
 
 GLOBAL OPTIONS:
    --file FILE, -f FILE  load config from FILE (default: "charts.yaml")
    --quiet, -q           silence output
+   --kube-context value  Set kubectl context. Uses current context by default
    --help, -h            show help
    --version, -v         print the version
 ```

main.go

@@ -21,6 +21,7 @@ func main() {
 	app := cli.NewApp()
 	app.Name = "helmfile"
 	app.Usage = ""
+	app.Version = "0.1.0"
 	app.Flags = []cli.Flag{
 		cli.StringFlag{
 			Name:  "file, f",
@@ -33,7 +34,7 @@ func main() {
 		},
 		cli.StringFlag{
 			Name: "kube-context",
-			Usage: "Set kubectl context",
+			Usage: "Set kubectl context. Uses current context by default",
 		},
 	}
 

state/state.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"errors"
 
 	"github.com/roboll/helmfile/helmexec"
 
@@ -164,7 +165,12 @@ func flagsForChart(chart *ChartSpec) ([]string, error) {
 	if len(chart.EnvValues) > 0 {
 		val := []string{}
 		for _, set := range chart.EnvValues {
-			val = append(val, fmt.Sprintf("%s=%s", set.Name, os.Getenv(set.Value)))
+			value, isSet := os.LookupEnv(set.Value)
+			if isSet {
+				val = append(val, fmt.Sprintf("%s=%s", set.Name, value))
+			} else {
+				return nil, errors.New(fmt.Sprintf("Unset env var: %s", set.Name))
+			}
 		}
 		flags = append(flags, "--set", strings.Join(val, ","))
 	}