Load from Azure Front Door support

Author: linglingye001

azureappconfiguration/azureappconfiguration.go

@@ -28,6 +28,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/afd"
 	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/jsonc"
 	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/refresh"
 	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/tracing"
@@ -51,12 +52,13 @@ type AzureAppConfiguration struct {
 	trimPrefixes         []string
 	watchedSettings      []WatchedSetting
 	loadBalancingEnabled bool
+	afdUsed              bool
 
 	// Settings used for refresh scenarios
 	sentinelETags          map[WatchedSetting]*azcore.ETag
 	watchAll               bool
-	kvETags                map[comparableSelector][]*azcore.ETag
-	ffETags                map[comparableSelector][]*azcore.ETag
+	kvWatchers             map[comparableSelector][]settingWatcher
+	ffWatchers             map[comparableSelector][]settingWatcher
 	keyVaultRefs           map[string]string // unversioned Key Vault references
 	kvRefreshTimer         refresh.Condition
 	secretRefreshTimer     refresh.Condition
@@ -117,11 +119,18 @@ func Load(ctx context.Context, authentication AuthenticationOptions, options *Op
 		credential:     options.KeyVaultOptions.Credential,
 	}
 
+	if authentication.Credential != nil {
+		if _, ok := authentication.Credential.(*afd.EmptyTokenCredential); ok {
+			azappcfg.afdUsed = true
+			azappcfg.tracingOptions.AfdUsed = true
+		}
+	}
+
 	if options.RefreshOptions.Enabled {
 		azappcfg.kvRefreshTimer = refresh.NewTimer(options.RefreshOptions.Interval)
 		azappcfg.watchedSettings = normalizedWatchedSettings(options.RefreshOptions.WatchedSettings)
 		azappcfg.sentinelETags = make(map[WatchedSetting]*azcore.ETag)
-		azappcfg.kvETags = make(map[comparableSelector][]*azcore.ETag)
+		azappcfg.kvWatchers = make(map[comparableSelector][]settingWatcher)
 		if len(options.RefreshOptions.WatchedSettings) == 0 {
 			azappcfg.watchAll = true
 		}
@@ -137,7 +146,7 @@ func Load(ctx context.Context, authentication AuthenticationOptions, options *Op
 		azappcfg.ffSelectors = getFeatureFlagSelectors(deduplicateSelectors(options.FeatureFlagOptions.Selectors))
 		if options.FeatureFlagOptions.RefreshOptions.Enabled {
 			azappcfg.ffRefreshTimer = refresh.NewTimer(options.FeatureFlagOptions.RefreshOptions.Interval)
-			azappcfg.ffETags = make(map[comparableSelector][]*azcore.ETag)
+			azappcfg.ffWatchers = make(map[comparableSelector][]settingWatcher)
 		}
 	}
 
@@ -150,6 +159,41 @@ func Load(ctx context.Context, authentication AuthenticationOptions, options *Op
 	return azappcfg, nil
 }
 
+func (azappcfg *AzureAppConfiguration) LoadFromAzureFrontDoor(ctx context.Context, endpoint string, options *Options) (*AzureAppConfiguration, error) {
+	if options == nil {
+		options = &Options{}
+	}
+
+	if options.ReplicaDiscoveryEnabled != nil && *options.ReplicaDiscoveryEnabled {
+		return nil, errors.New("replica discovery is not supported when loading from Azure Front Door. For guidance on how to take advantage of geo-replication when Azure Front Door is used, visit https://aka.ms/appconfig/geo-replication-with-afd")
+	}
+
+	if options.LoadBalancingEnabled {
+		return nil, errors.New("load balancing is not supported when loading from Azure Front Door. For guidance on how to take advantage of geo-replication when Azure Front Door is used, visit https://aka.ms/appconfig/geo-replication-with-afd")
+	}
+
+	if options.RefreshOptions.Enabled &&
+		len(options.RefreshOptions.WatchedSettings) > 0 {
+		return nil, errors.New("specifying watched settings is not supported when loading from Azure Front Door. If refresh is enabled, all loaded configuration settings will be watched automatically")
+	}
+
+	disableReplicaDiscovery := false
+	options.ReplicaDiscoveryEnabled = &disableReplicaDiscovery
+
+	if options.ClientOptions == nil {
+		options.ClientOptions = &azappconfig.ClientOptions{}
+	}
+
+	options.ClientOptions.PerRetryPolicies = append(options.ClientOptions.PerRetryPolicies, afd.NewAnonymousRequestPipelinePolicy(), afd.NewRemoveSyncTokenPipelinePolicy())
+
+	authOptions := AuthenticationOptions{
+		Endpoint:   endpoint,
+		Credential: afd.NewEmptyTokenCredential(),
+	}
+
+	return Load(ctx, authOptions, options)
+}
+
 // Unmarshal parses the configuration and stores the result in the value pointed to v. It builds a hierarchical configuration structure based on key separators.
 // It supports converting values to appropriate target types.
 //
@@ -432,7 +476,7 @@ func (azappcfg *AzureAppConfiguration) loadKeyValues(ctx context.Context, settin
 	maps.Copy(kvSettings, secrets)
 	azappcfg.keyValues = kvSettings
 	azappcfg.keyVaultRefs = getUnversionedKeyVaultRefs(keyVaultRefs)
-	azappcfg.kvETags = settingsResponse.pageETags
+	azappcfg.kvWatchers = settingsResponse.pageWatchers
 
 	return nil
 }
@@ -509,7 +553,7 @@ func (azappcfg *AzureAppConfiguration) loadFeatureFlags(ctx context.Context, set
 		},
 	}
 
-	azappcfg.ffETags = settingsResponse.pageETags
+	azappcfg.ffWatchers = settingsResponse.pageWatchers
 	azappcfg.featureFlags = ffSettings
 
 	return nil
@@ -857,10 +901,10 @@ func normalizedWatchedSettings(s []WatchedSetting) []WatchedSetting {
 func (azappcfg *AzureAppConfiguration) newKeyValueRefreshClient(client *azappconfig.Client) refreshClient {
 	var monitor eTagsClient
 	if azappcfg.watchAll {
-		monitor = &pageETagsClient{
+		monitor = &pageWatcherClient{
 			client:         client,
 			tracingOptions: azappcfg.tracingOptions,
-			pageETags:      azappcfg.kvETags,
+			pageWatchers:   azappcfg.kvWatchers,
 		}
 	} else {
 		monitor = &watchedSettingClient{
@@ -892,10 +936,10 @@ func (azappcfg *AzureAppConfiguration) newFeatureFlagRefreshClient(client *azapp
 			client:         client,
 			tracingOptions: azappcfg.tracingOptions,
 		},
-		monitor: &pageETagsClient{
+		monitor: &pageWatcherClient{
 			client:         client,
 			tracingOptions: azappcfg.tracingOptions,
-			pageETags:      azappcfg.ffETags,
+			pageWatchers:   azappcfg.ffWatchers,
 		},
 	}
 }

azureappconfiguration/azureappconfiguration_test.go

@@ -15,7 +15,6 @@ import (
 
 	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/fm"
 	"github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration/internal/tracing"
-	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
 	"github.com/Azure/azure-sdk-for-go/sdk/data/azappconfig/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
@@ -128,7 +127,7 @@ func TestLoadFeatureFlags_Success(t *testing.T) {
 			{Key: toPtr(".appconfig.featureflag/Beta"), Value: &value1, ContentType: toPtr(featureFlagContentType)},
 			{Key: toPtr(".appconfig.featureflag/Alpha"), Value: &value2, ContentType: toPtr(featureFlagContentType)},
 		},
-		pageETags: map[comparableSelector][]*azcore.ETag{},
+		pageWatchers: map[comparableSelector][]settingWatcher{},
 	}
 
 	mockClient.On("getSettings", ctx).Return(mockResponse, nil)
@@ -1545,7 +1544,7 @@ func TestLoadFeatureFlags_TracingUpdated(t *testing.T) {
 				ContentType: toPtr(featureFlagContentType),
 			},
 		},
-		pageETags: map[comparableSelector][]*azcore.ETag{},
+		pageWatchers: map[comparableSelector][]settingWatcher{},
 	}
 
 	mockClient.On("getSettings", ctx).Return(mockResponse, nil)
@@ -1639,7 +1638,7 @@ func TestLoadKeyValues_WithTagFilter(t *testing.T) {
 				},
 			},
 		},
-		pageETags: map[comparableSelector][]*azcore.ETag{},
+		pageWatchers: map[comparableSelector][]settingWatcher{},
 	}
 
 	mockClient.On("getSettings", ctx).Return(mockResponse, nil)
@@ -1695,7 +1694,7 @@ func TestLoadKeyValues_WithMultipleTagFilters(t *testing.T) {
 				},
 			},
 		},
-		pageETags: map[comparableSelector][]*azcore.ETag{},
+		pageWatchers: map[comparableSelector][]settingWatcher{},
 	}
 
 	mockClient.On("getSettings", ctx).Return(mockResponse, nil)

azureappconfiguration/internal/afd/empty_token_cred.go

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package afd
+
+import (
+	"context"
+	"math"
+	"time"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+)
+
+type EmptyTokenCredential struct{}
+
+func (e *EmptyTokenCredential) GetToken(ctx context.Context, options policy.TokenRequestOptions) (azcore.AccessToken, error) {
+	return azcore.AccessToken{
+		Token:     "",
+		ExpiresOn: time.Unix(math.MaxInt64, 0),
+	}, nil
+}
+
+func NewEmptyTokenCredential() azcore.TokenCredential {
+	return &EmptyTokenCredential{}
+}

azureappconfiguration/internal/afd/policy.go

@@ -0,0 +1,38 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package afd
+
+import (
+	"net/http"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+)
+
+type AnonymousRequestPipelinePolicy struct{}
+
+type RemoveSyncTokenPipelinePolicy struct{}
+
+func NewAnonymousRequestPipelinePolicy() *AnonymousRequestPipelinePolicy {
+	return &AnonymousRequestPipelinePolicy{}
+}
+
+func NewRemoveSyncTokenPipelinePolicy() *RemoveSyncTokenPipelinePolicy {
+	return &RemoveSyncTokenPipelinePolicy{}
+}
+
+func (p *AnonymousRequestPipelinePolicy) Do(req *policy.Request) (*http.Response, error) {
+	if req.Raw().Header.Get("Authorization") != "" {
+		req.Raw().Header.Del("Authorization")
+	}
+
+	return req.Next()
+}
+
+func (p *RemoveSyncTokenPipelinePolicy) Do(req *policy.Request) (*http.Response, error) {
+	if req.Raw().Header.Get("Sync-Token") != "" {
+		req.Raw().Header.Del("Sync-Token")
+	}
+
+	return req.Next()
+}

azureappconfiguration/internal/tracing/tracing.go

@@ -43,6 +43,7 @@ const (
 	FailoverRequestTag               = "Failover"
 	ReplicaCountKey                  = "ReplicaCount"
 	LoadBalancingEnabledTag          = "LB"
+	AFDUsedTag                       = "AFD"
 
 	// Feature flag usage tracing
 	FMGoVerEnv           = "MS_FEATURE_MANAGEMENT_GO_VERSION"
@@ -77,6 +78,7 @@ type Options struct {
 	IsFailoverRequest                bool
 	ReplicaCount                     int
 	IsLoadBalancingEnabled           bool
+	AfdUsed                          bool
 	FeatureFlagTracing               *FeatureFlagTracing
 	FMVersion                        string
 }
@@ -143,6 +145,10 @@ func CreateCorrelationContextHeader(ctx context.Context, options Options) http.H
 		features = append(features, LoadBalancingEnabledTag)
 	}
 
+	if options.AfdUsed {
+		features = append(features, AFDUsedTag)
+	}
+
 	if len(features) > 0 {
 		featureStr := FeaturesKey + "=" + strings.Join(features, DelimiterPlus)
 		output = append(output, featureStr)

azureappconfiguration/options.go

@@ -91,7 +91,7 @@ type Selector struct {
 // comparableKey returns a comparable representation of the Selector that can be used as a map key.
 // This method creates a deterministic string representation by sorting the TagFilter slice.
 func (s Selector) comparableKey() comparableSelector {
-	cs :=  comparableSelector{
+	cs := comparableSelector{
 		KeyFilter:    s.KeyFilter,
 		LabelFilter:  s.LabelFilter,
 		SnapshotName: s.SnapshotName,