feat: support HELMFILE_KUBE_CONTEXT env var for default kube context (#2593)

* feat: support HELMFILE_KUBE_CONTEXT env var for default kube context

Mirrors the existing HELMFILE_ENVIRONMENT pattern: the --kube-context
CLI flag takes precedence, falling back to HELMFILE_KUBE_CONTEXT when
unset.

Refs #1213.

Signed-off-by: Dominik Schmidt <dev@dominik-schmidt.de>

* docs: mention HELMFILE_KUBE_CONTEXT in cli.md and templating.md

Signed-off-by: Dominik Schmidt <dev@dominik-schmidt.de>

---------

Signed-off-by: Dominik Schmidt <dev@dominik-schmidt.de>

cmd/root.go

@@ -136,7 +136,7 @@ func setGlobalOptionsForRootCmd(fs *pflag.FlagSet, globalOptions *config.GlobalO
 	fs.BoolVar(&globalOptions.HelmOCIPlainHTTP, "oci-plain-http", false, `use plain HTTP for OCI registries (required for local/insecure registries in Helm 4)`)
 	fs.BoolVarP(&globalOptions.Quiet, "quiet", "q", false, "Silence output. Equivalent to log-level warn")
 	fs.StringVar(&globalOptions.Kubeconfig, "kubeconfig", "", "Use a particular kubeconfig file")
-	fs.StringVar(&globalOptions.KubeContext, "kube-context", "", "Set kubectl context. Uses current context by default")
+	fs.StringVar(&globalOptions.KubeContext, "kube-context", "", `Set kubectl context. Overrides "HELMFILE_KUBE_CONTEXT" OS environment variable when specified. Uses current kubectl context by default`)
 	fs.BoolVar(&globalOptions.Debug, "debug", false, "Enable verbose output for Helm and set log-level to debug, this disables --quiet/-q effect")
 	fs.BoolVar(&globalOptions.Color, "color", false, "Output with color")
 	fs.BoolVar(&globalOptions.NoColor, "no-color", false, "Output without color")

docs/cli.md

@@ -49,7 +49,7 @@ Flags:
   -b, --helm-binary string                    Path to the helm binary (default "helm")
   -h, --help                                  help for helmfile
   -i, --interactive                           Request confirmation before attempting to modify clusters
-      --kube-context string                   Set kubectl context. Uses current context by default
+      --kube-context string                   Set kubectl context. Overrides "HELMFILE_KUBE_CONTEXT" OS environment variable when specified. Uses current kubectl context by default
   -k, --kustomize-binary string               Path to the kustomize binary (default "kustomize")
       --log-level string                      Set log level, default info (default "info")
   -n, --namespace string                      Set namespace. Uses the namespace set in the context by default, and is available in templates as {{ .Namespace }}

docs/templating.md

@@ -66,6 +66,7 @@ Helmfile uses some OS environment variables to override default behaviour:
 * `HELMFILE_USE_HELM_STATUS_TO_CHECK_RELEASE_EXISTENCE` - expecting non-empty value to use `helm status` to check release existence, instead of `helm list` which is the default behaviour
 * `HELMFILE_EXPERIMENTAL` - enable experimental features, expecting `true` lower case
 * `HELMFILE_ENVIRONMENT` - specify [Helmfile environment](environments.md), it has lower priority than CLI argument `--environment`
+* `HELMFILE_KUBE_CONTEXT` - specify the kubectl context, it has lower priority than CLI argument `--kube-context`
 * `HELMFILE_TEMPDIR` - specify directory to store temporary files
 * `HELMFILE_UPGRADE_NOTICE_DISABLED` - expecting any non-empty value to skip the check for the latest version of Helmfile in [helmfile version](cli.md#version)
 * `HELMFILE_GO_YAML_V3` - use *go.yaml.in/yaml/v3* instead of *go.yaml.in/yaml/v2*.  It's `false` by default in Helmfile v0.x, and `true` in Helmfile v1.x.

pkg/config/global.go

@@ -124,7 +124,17 @@ func (g *GlobalImpl) Kubeconfig() string {
 
 // KubeContext returns the name of the kubectl context to use.
 func (g *GlobalImpl) KubeContext() string {
-	return g.GlobalOptions.KubeContext
+	var kubeContext string
+
+	switch {
+	case g.GlobalOptions.KubeContext != "":
+		kubeContext = g.GlobalOptions.KubeContext
+	case os.Getenv("HELMFILE_KUBE_CONTEXT") != "":
+		kubeContext = os.Getenv("HELMFILE_KUBE_CONTEXT")
+	default:
+		kubeContext = ""
+	}
+	return kubeContext
 }
 
 // Namespace returns the namespace to use.

pkg/config/global_test.go

@@ -45,3 +45,40 @@ func TestFileOrDir(t *testing.T) {
 	}
 	os.Unsetenv(envvar.FilePath)
 }
+
+// TestKubeContext tests the kube-context flag and HELMFILE_KUBE_CONTEXT env var fallback
+func TestKubeContext(t *testing.T) {
+	tests := []struct {
+		opts     GlobalOptions
+		env      string
+		expected string
+	}{
+		{
+			opts:     GlobalOptions{},
+			env:      "",
+			expected: "",
+		},
+		{
+			opts:     GlobalOptions{},
+			env:      "envset",
+			expected: "envset",
+		},
+		{
+			opts:     GlobalOptions{KubeContext: "flagset"},
+			env:      "",
+			expected: "flagset",
+		},
+		{
+			opts:     GlobalOptions{KubeContext: "flagset"},
+			env:      "envset",
+			expected: "flagset",
+		},
+	}
+
+	for _, test := range tests {
+		os.Setenv(envvar.KubeContext, test.env)
+		received := NewGlobalImpl(&test.opts).KubeContext()
+		require.Equalf(t, test.expected, received, "KubeContext expected %s, received %s", test.expected, received)
+	}
+	os.Unsetenv(envvar.KubeContext)
+}

pkg/envvar/const.go

@@ -9,6 +9,7 @@ const (
 	DisableRunnerUniqueID = "HELMFILE_DISABLE_RUNNER_UNIQUE_ID"
 	Experimental          = "HELMFILE_EXPERIMENTAL" // environment variable for experimental features, expecting "true" lower case
 	Environment           = "HELMFILE_ENVIRONMENT"
+	KubeContext           = "HELMFILE_KUBE_CONTEXT"
 	FilePath              = "HELMFILE_FILE_PATH"
 	TempDir               = "HELMFILE_TEMPDIR"
 	UpgradeNoticeDisabled = "HELMFILE_UPGRADE_NOTICE_DISABLED"