honk-env.diff

diff --git a/main.go b/main.go
index 4bc5c9a..54b5b3f 100644
--- a/main.go
+++ b/main.go
@@ -103,8 +103,8 @@ func main() {
 			usage()
 		},
 	}
-	flag.StringVar(&dataDir, "datadir", dataDir, "data directory")
-	flag.StringVar(&viewDir, "viewdir", viewDir, "view directory")
+	flag.StringVar(&dataDir, "datadir", getFromEnvOrDefault("DATA_DIR", dataDir), "data directory")
+	flag.StringVar(&viewDir, "viewdir", getFromEnvOrDefault("VIEW_DIR", viewDir), "view directory")
 	flag.Usage = usage
 
 	flag.Parse()
diff --git a/util.go b/util.go
index 7dad7c7..e59b9c9 100644
--- a/util.go
+++ b/util.go
@@ -461,3 +461,11 @@ func openListener() (net.Listener, error) {
 	listenSocket = listener
 	return listener, nil
 }
+
+func getFromEnvOrDefault(key, value string) string {
+	v, ok := os.LookupEnv(key)
+	if !ok {
+		return value
+	}
+	return v
+}