From 557f1a39749344ce0bccee02a31ae3e49ff706c9 Mon Sep 17 00:00:00 2001
From: Markus Wennrich <markus.wennrich@f-i-ts.de>
Date: Tue, 29 Sep 2026 09:07:18 +0200
Subject: [PATCH] enable environment based configuration

---
 README.md            | 6 ++++++
 cmd/config/config.go | 2 +-
 cmd/root.go          | 5 +++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 04a72be..2be37a5 100644
--- a/README.md
+++ b/README.md
@@ -110,3 +110,9 @@ $ metalctlv2 ctx add <context-name> --activate --default-project <project-uuid>
 ```
 
 The configuration file is by default written to `~/.metal-stack/config.yaml`.
+
+## Environment Variables
+
+All flags can also be provided as environment variables prefixed with `METAL_STACK_`. The flag name is uppercased and dashes are replaced by underscores, e.g. `--api-url` becomes `METAL_STACK_API_URL`.
+
+An explicitly provided flag takes precedence over an environment variable, which in turn takes precedence over the context in `~/.metal-stack/config.yaml`.
diff --git a/cmd/config/config.go b/cmd/config/config.go
index fdc692c..a83c3b5 100644
--- a/cmd/config/config.go
+++ b/cmd/config/config.go
@@ -21,7 +21,7 @@ const (
 	// BinaryName is the name of the cli in all help texts
 	BinaryName = "metalctlv2"
 	// ConfigDir is the directory in either the homedir or in /etc where the cli searches for a file config.yaml
-	// also used as prefix for environment based configuration, e.g. METAL_STACK_CLOUD_ will be the variable prefix.
+	// also used as prefix for environment based configuration, e.g. METAL_STACK_ will be the variable prefix.
 	ConfigDir = "metal-stack"
 )
 
diff --git a/cmd/root.go b/cmd/root.go
index 821a391..e9adb01 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -3,6 +3,7 @@ package cmd
 import (
 	"log/slog"
 	"os"
+	"strings"
 
 	client "github.com/metal-stack/api/go/client"
 	"github.com/metal-stack/metal-lib/pkg/genericcli"
@@ -42,6 +43,10 @@ func Execute() {
 }
 
 func NewRootCmd(c *config.Config) *cobra.Command {
+	viper.SetEnvPrefix(strings.ToUpper(config.ConfigDir))
+	viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
+	viper.AutomaticEnv()
+
 	rootCmd := &cobra.Command{
 		Use:          config.BinaryName,
 		Aliases:      []string{"m"},