feat(featureflags): improved feature flag handling [EE-4609] (#8222)

* updated and improved feature flags using new module

* merge init into parse

* update the package documentation

* better docs

* minor tidy

pkg/featureflags/featureflags_test.go

@@ -0,0 +1,75 @@
+package featureflags
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_enableFeaturesFromFlags(t *testing.T) {
+	is := assert.New(t)
+
+	supportedFeatures := []Feature{"supported", "supported2", "supported3", "supported4", "supported5"}
+
+	t.Run("supported features should be supported", func(t *testing.T) {
+		Init(supportedFeatures)
+
+		for _, featureFlag := range supportedFeatures {
+			is.True(IsSupported(featureFlag))
+		}
+	})
+
+	t.Run("unsupported features should not be supported", func(t *testing.T) {
+		Init(supportedFeatures)
+
+		is.False(IsSupported("unsupported"))
+	})
+
+	tests := []struct {
+		cliFeatureFlags []string
+		envFeatureFlags []string
+	}{
+		{[]string{"supported", "supported2"}, []string{"supported3", "supported4"}},
+	}
+
+	for _, test := range tests {
+		Init(supportedFeatures)
+
+		os.Unsetenv("PORTAINER_FEATURE_FLAGS")
+		os.Setenv("PORTAINER_FEATURE_FLAGS", strings.Join(test.envFeatureFlags, ","))
+
+		t.Run("testing", func(t *testing.T) {
+			Parse(test.cliFeatureFlags)
+			supported := toFeatureMap(test.cliFeatureFlags, test.envFeatureFlags)
+
+			// add env flags to supported flags
+			for _, featureFlag := range test.envFeatureFlags {
+				supported[Feature(featureFlag)] = true
+			}
+
+			for _, featureFlag := range supportedFeatures {
+				if _, ok := supported[featureFlag]; ok {
+					is.True(IsEnabled(featureFlag))
+				} else {
+					is.False(IsEnabled(featureFlag))
+				}
+			}
+		})
+	}
+}
+
+// helper
+func toFeatureMap(cliFeatures []string, envFeatures []string) map[Feature]bool {
+	m := map[Feature]bool{}
+	for _, s := range cliFeatures {
+		m[Feature(s)] = true
+	}
+
+	for _, s := range envFeatures {
+		m[Feature(s)] = true
+	}
+
+	return m
+}