Package for feature toggles

pkg/features/features.go

@@ -0,0 +1,37 @@
+package features
+
+import (
+	"os"
+)
+
+const ComponentsUpgradesEnvVar = "COMPONENTS_UPGRADE"
+
+var cache = newMutexMap()
+
+type Feature struct {
+	Name     string
+	IsActive func() bool
+}
+
+func IsActive(feature Feature) bool {
+	return feature.IsActive()
+}
+
+func isActiveForEnvVar(envVar string) func() bool {
+	return func() bool {
+		active, ok := cache.load(envVar)
+		if !ok {
+			active = os.Getenv(envVar) == "true"
+			cache.store(envVar, active)
+		}
+
+		return active
+	}
+}
+
+func ComponentsUpgrade() Feature {
+	return Feature{
+		Name:     "Core components upgrade",
+		IsActive: isActiveForEnvVar(ComponentsUpgradesEnvVar),
+	}
+}

pkg/features/features_test.go

@@ -0,0 +1,54 @@
+package features
+
+import (
+	"os"
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+const fakeFeatureEnvVar = "fakeFeatureEnvVar"
+
+func fakeFeature() Feature {
+	return Feature{
+		Name:     "Core components upgrade",
+		IsActive: isActiveForEnvVar(fakeFeatureEnvVar),
+	}
+}
+
+func setupContext(t *testing.T) {
+	envVarOrgValue, set := os.LookupEnv(fakeFeatureEnvVar)
+	t.Cleanup(func() {
+		// cleanup cache
+		cache = newMutexMap()
+		if set {
+			os.Setenv(fakeFeatureEnvVar, envVarOrgValue)
+		} else {
+			os.Unsetenv(fakeFeatureEnvVar)
+		}
+	})
+}
+
+func TestIsActiveEnvVarUnset(t *testing.T) {
+	g := NewWithT(t)
+	setupContext(t)
+
+	os.Unsetenv(fakeFeatureEnvVar)
+	g.Expect(IsActive(fakeFeature())).To(BeFalse())
+}
+
+func TestIsActiveEnvVarSetFalse(t *testing.T) {
+	g := NewWithT(t)
+	setupContext(t)
+
+	os.Setenv(fakeFeatureEnvVar, "false")
+	g.Expect(IsActive(fakeFeature())).To(BeFalse())
+}
+
+func TestIsActiveEnvVarSetTrue(t *testing.T) {
+	g := NewWithT(t)
+	setupContext(t)
+
+	g.Expect(os.Setenv(fakeFeatureEnvVar, "true")).To(Succeed())
+	g.Expect(IsActive(fakeFeature())).To(BeTrue())
+}

pkg/features/mutexmap.go

@@ -0,0 +1,27 @@
+package features
+
+import "sync"
+
+func newMutexMap() *mutexMap {
+	return &mutexMap{
+		internal: make(map[string]bool),
+	}
+}
+
+type mutexMap struct {
+	internal map[string]bool
+	sync.RWMutex
+}
+
+func (m *mutexMap) load(key string) (value bool, ok bool) {
+	m.RLock()
+	result, ok := m.internal[key]
+	m.RUnlock()
+	return result, ok
+}
+
+func (m *mutexMap) store(key string, value bool) {
+	m.Lock()
+	m.internal[key] = value
+	m.Unlock()
+}

pkg/features/mutexmap_test.go

@@ -0,0 +1,23 @@
+package features
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+func TestMutextMapLoadAndStore(t *testing.T) {
+	g := NewWithT(t)
+	m := newMutexMap()
+
+	key := "key"
+	value := true
+	v, ok := m.load(key)
+	g.Expect(ok).To(BeFalse())
+	g.Expect(v).To(BeFalse())
+
+	m.store(key, value)
+	v, ok = m.load(key)
+	g.Expect(ok).To(BeTrue())
+	g.Expect(v).To(Equal(value))
+}