fix: work around Viper dropping nil-value keys

internal/config/config.go

@@ -97,7 +97,7 @@ func parseConfig(configFile string) (*Config, error) {
 		slog.Info("Configuration file found", "path", "concierge.yaml")
 	}
 
-	fixNilSnapEntries(viper.GetViper())
+	fixNilYAMLEntries(viper.GetViper())
 
 	conf := &Config{}
 	err := viper.Unmarshal(conf)

internal/config/config_test.go

@@ -136,6 +136,52 @@ host:
 	}
 }
 
+func TestK8sFeaturesWithoutConfig(t *testing.T) {
+	yamlConfig := `
+providers:
+  k8s:
+    enable: true
+    bootstrap: true
+    features:
+      dns:
+      ingress:
+      local-storage:
+      network:
+      load-balancer:
+        l2-mode: "true"
+        cidrs: 10.0.0.0/24
+`
+
+	tmpFile, err := os.CreateTemp("", "concierge-test-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = os.Remove(tmpFile.Name()) }()
+
+	if _, err := tmpFile.Write([]byte(yamlConfig)); err != nil {
+		t.Fatal(err)
+	}
+	if err := tmpFile.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := parseConfig(tmpFile.Name())
+	if err != nil {
+		t.Fatalf("Failed to parse config: %v", err)
+	}
+
+	for _, name := range []string{"dns", "ingress", "local-storage", "network", "load-balancer"} {
+		if _, ok := cfg.Providers.K8s.Features[name]; !ok {
+			t.Fatalf("expected k8s feature %q to be present in map, got: %v", name, cfg.Providers.K8s.Features)
+		}
+	}
+
+	lb := cfg.Providers.K8s.Features["load-balancer"]
+	if lb["l2-mode"] != "true" || lb["cidrs"] != "10.0.0.0/24" {
+		t.Fatalf("expected load-balancer config preserved, got: %v", lb)
+	}
+}
+
 func TestExtraBootstrapArgsFromYAML(t *testing.T) {
 	yamlConfig := `
 juju:

internal/config/presets.go

@@ -42,18 +42,26 @@ func Preset(preset string) (*Config, error) {
 	return loadPreset(data)
 }
 
-// fixNilSnapEntries replaces nil-valued snap entries with empty maps so that
-// Viper's Unmarshal does not silently drop bare YAML keys like "charmcraft:".
-func fixNilSnapEntries(v *viper.Viper) {
-	if snaps, ok := v.Get("host.snaps").(map[string]any); ok {
-		for name, val := range snaps {
+// fixNilMapEntries replaces nil-valued entries within the map at the given
+// Viper key with empty maps, so that Unmarshal does not silently drop bare
+// YAML keys like "charmcraft:" or "ingress:".
+func fixNilMapEntries(v *viper.Viper, key string) {
+	if entries, ok := v.Get(key).(map[string]any); ok {
+		for name, val := range entries {
 			if val == nil {
-				v.Set("host.snaps."+name, map[string]any{})
+				v.Set(key+"."+name, map[string]any{})
 			}
 		}
 	}
 }
 
+// fixNilYAMLEntries fixes bare YAML keys that Viper would otherwise silently
+// drop when unmarshalling into typed maps.
+func fixNilYAMLEntries(v *viper.Viper) {
+	fixNilMapEntries(v, "host.snaps")
+	fixNilMapEntries(v, "providers.k8s.features")
+}
+
 // loadPreset parses YAML data into a Config using a fresh Viper instance.
 func loadPreset(data []byte) (*Config, error) {
 	v := viper.New()
@@ -63,7 +71,7 @@ func loadPreset(data []byte) (*Config, error) {
 		return nil, fmt.Errorf("failed to parse preset: %w", err)
 	}
 
-	fixNilSnapEntries(v)
+	fixNilYAMLEntries(v)
 
 	conf := &Config{}
 	if err := v.Unmarshal(conf); err != nil {

tests/provider-k8s/concierge.yaml

@@ -4,7 +4,10 @@ providers:
     bootstrap: true
     channel: 1.32-classic/stable
     features:
+      dns:
+      ingress:
       local-storage:
+      network:
       load-balancer:
         l2-mode: true
         cidrs: 10.64.140.43/32

tests/provider-k8s/task.yaml

@@ -15,9 +15,14 @@ execute: |
   echo $list | MATCH juju
   echo $list | MATCH kubectl
 
-  sudo k8s status --output-format yaml | yq '.dns.enabled' | MATCH true
-  sudo k8s status --output-format yaml | yq '.load-balancer.enabled' | MATCH true
-  sudo k8s status --output-format yaml | yq '.load-balancer.message' | MATCH "enabled, L2 mode"
+  status="$(sudo k8s status --output-format yaml)"
+  # Bare-key features (no inline config) must still be enabled — see issue #189.
+  echo "$status" | yq '.dns.enabled' | MATCH true
+  echo "$status" | yq '.ingress.enabled' | MATCH true
+  echo "$status" | yq '.["local-storage"].enabled' | MATCH true
+  echo "$status" | yq '.network.enabled' | MATCH true
+  echo "$status" | yq '.["load-balancer"].enabled' | MATCH true
+  echo "$status" | yq '.["load-balancer"].message' | MATCH "enabled, L2 mode"
   sudo k8s get | yq '.load-balancer.cidrs' | MATCH "10.64.140.43/32"
 
   kubectl config current-context | MATCH "k8s"