Settings: Allow setting feature toggles via GF_FEATURE_TOGGLES_<feature_name> env vars

pkg/setting/setting.go

@@ -655,6 +655,25 @@ func (cfg *Cfg) applyEnvVariableOverrides(file *ini.File) error {
 		}
 	}
 
+	// Override feature toggles from environment variables.
+	// This is done separately because feature toggles are not stored in the ini file.
+	// Overriding feature toggles from environment variables is useful when setting them to `false`.
+	// To set them to `true`, `GF_FEATURE_TOGGLES_ENABLED` can also be used.
+	const featureTogglesPrefix = "GF_FEATURE_TOGGLES_"
+	featuresSection := file.Section("feature_toggles")
+	for _, kv := range os.Environ() {
+		parts := strings.SplitN(kv, "=", 2)
+		if len(parts) != 2 {
+			continue
+		}
+		featureName := parts[0]
+		featureValue := parts[1]
+		if !strings.HasPrefix(featureName, featureTogglesPrefix) {
+			continue
+		}
+		featuresSection.Key(strings.TrimPrefix(featureName, featureTogglesPrefix)).SetValue(featureValue)
+		cfg.appliedEnvOverrides = append(cfg.appliedEnvOverrides, fmt.Sprintf("%s=%s", featureName, RedactedValue(featureName, featureValue)))
+	}
 	return nil
 }
 

pkg/setting/setting_test.go

@@ -681,3 +681,30 @@ func TestDynamicSection(t *testing.T) {
 		assert.Equal(t, value, ds.section.Key(key).String())
 	})
 }
+
+func TestFeatureTogglesEnvVars(t *testing.T) {
+	t.Run("should read feature toggles from ini", func(t *testing.T) {
+		cfg := NewCfg()
+		const feature = "someFeature"
+
+		err := cfg.Load(CommandLineArgs{HomePath: "../../", Config: "testdata/feature_toggles.ini"})
+		require.NoError(t, err)
+
+		require.True(t, cfg.IsFeatureToggleEnabled(feature))
+	})
+
+	t.Run("should override feature toggles from env vars", func(t *testing.T) {
+		cfg := NewCfg()
+		const someFeature = "someFeature"
+		const otherFeature = "otherFeature"
+
+		require.NoError(t, os.Setenv("GF_FEATURE_TOGGLES_"+someFeature, "false"))
+		require.NoError(t, os.Setenv("GF_FEATURE_TOGGLES_"+otherFeature, "true"))
+
+		err := cfg.Load(CommandLineArgs{HomePath: "../../", Config: "testdata/feature_toggles.ini"})
+		require.NoError(t, err)
+
+		require.False(t, cfg.IsFeatureToggleEnabled(someFeature))
+		require.True(t, cfg.IsFeatureToggleEnabled(otherFeature))
+	})
+}

pkg/setting/testdata/feature_toggles.ini

@@ -0,0 +1,7 @@
+app_mode = production
+
+[server]
+domain = test.com
+
+[feature_toggles]
+someFeature = true