feat: support azure blob sync (open-feature#1428)

- adds support for Azure Blob Storage sync

Signed-off-by: Matthew Wilson <54033231+wilson-matthew@users.noreply.github.com>

core/go.mod

@@ -49,6 +49,13 @@ require (
 	cloud.google.com/go/compute/metadata v0.5.0 // indirect
 	cloud.google.com/go/iam v1.1.13 // indirect
 	cloud.google.com/go/storage v1.43.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.14.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.7.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.10.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.3.2 // indirect
+	github.com/Azure/go-autorest v14.2.0+incompatible // indirect
+	github.com/Azure/go-autorest/autorest/to v0.4.0 // indirect
+	github.com/AzureAD/microsoft-authentication-library-for-go v1.2.2 // indirect
 	github.com/barkimedes/go-deepcopy v0.0.0-20220514131651-17c30cfc62df // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
@@ -65,6 +72,7 @@ require (
 	github.com/go-openapi/jsonreference v0.21.0 // indirect
 	github.com/go-openapi/swag v0.23.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang-jwt/jwt/v5 v5.2.1 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/gnostic-models v0.6.8 // indirect
@@ -80,10 +88,12 @@ require (
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/compress v1.17.9 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.7 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_model v0.6.1 // indirect

core/pkg/sync/blob/blob_sync.go

@@ -10,7 +10,8 @@ import (
 	"github.com/open-feature/flagd/core/pkg/logger"
 	"github.com/open-feature/flagd/core/pkg/sync"
 	"gocloud.dev/blob"
-	_ "gocloud.dev/blob/gcsblob" // needed to initialize GCS driver
+	_ "gocloud.dev/blob/azureblob" // needed to initialize Azure Blob Storage driver
+	_ "gocloud.dev/blob/gcsblob"   // needed to initialize GCS driver
 )
 
 type Sync struct {

core/pkg/sync/builder/syncbuilder.go

@@ -31,6 +31,7 @@ const (
 	syncProviderKubernetes = "kubernetes"
 	syncProviderHTTP       = "http"
 	syncProviderGcs        = "gcs"
+	syncProviderAzblob     = "azblob"
 )
 
 var (
@@ -41,6 +42,7 @@ var (
 	regGRPCCustomResolver *regexp.Regexp
 	regFile               *regexp.Regexp
 	regGcs                *regexp.Regexp
+	regAzblob             *regexp.Regexp
 )
 
 func init() {
@@ -51,6 +53,7 @@ func init() {
 	regGRPCCustomResolver = regexp.MustCompile("^" + grpc.SupportedScheme)
 	regFile = regexp.MustCompile("^file:")
 	regGcs = regexp.MustCompile("^gs://.+?/")
+	regAzblob = regexp.MustCompile("^azblob://.+?/")
 }
 
 type ISyncBuilder interface {
@@ -113,11 +116,15 @@ func (sb *SyncBuilder) syncFromConfig(sourceConfig sync.SourceConfig, logger *lo
 	case syncProviderGcs:
 		logger.Debug(fmt.Sprintf("using blob sync-provider with gcs driver for: %s", sourceConfig.URI))
 		return sb.newGcs(sourceConfig, logger), nil
+	case syncProviderAzblob:
+		logger.Debug(fmt.Sprintf("using blob sync-provider with azblob driver for: %s", sourceConfig.URI))
+		return sb.newAzblob(sourceConfig, logger)
 
 	default:
-		return nil, fmt.Errorf("invalid sync provider: %s, must be one of with '%s', '%s', '%s', %s', '%s' or '%s'",
+		return nil, fmt.Errorf("invalid sync provider: %s, must be one of with "+
+			"'%s', '%s', '%s', '%s', '%s', '%s', '%s' or '%s'",
 			sourceConfig.Provider, syncProviderFile, syncProviderFsNotify, syncProviderFileInfo,
-			syncProviderKubernetes, syncProviderHTTP, syncProviderKubernetes)
+			syncProviderKubernetes, syncProviderHTTP, syncProviderGrpc, syncProviderGcs, syncProviderAzblob)
 	}
 }
 
@@ -240,6 +247,43 @@ func (sb *SyncBuilder) newGcs(config sync.SourceConfig, logger *logger.Logger) *
 	}
 }
 
+func (sb *SyncBuilder) newAzblob(config sync.SourceConfig, logger *logger.Logger) (*blobSync.Sync, error) {
+	// Required to generate the azblob service URL
+	storageAccountName := os.Getenv("AZURE_STORAGE_ACCOUNT")
+	if storageAccountName == "" {
+		return nil, fmt.Errorf("environment variable AZURE_STORAGE_ACCOUNT not set or is blank")
+	}
+	if regexp.MustCompile(`\s`).MatchString(storageAccountName) {
+		return nil, fmt.Errorf("environment variable AZURE_STORAGE_ACCOUNT contains whitespace")
+	}
+
+	// Extract bucket uri and object name from the full URI:
+	// azblob://bucket/path/to/object results in azblob://bucket/ as bucketUri and
+	// path/to/object as an object name.
+	bucketURI := regAzblob.FindString(config.URI)
+	objectName := regAzblob.ReplaceAllString(config.URI, "")
+
+	// Defaults to 5 seconds if interval is not set.
+	var interval uint32 = 5
+	if config.Interval != 0 {
+		interval = config.Interval
+	}
+
+	return &blobSync.Sync{
+		Bucket: bucketURI,
+		Object: objectName,
+
+		BlobURLMux: blob.DefaultURLMux(),
+
+		Logger: logger.WithFields(
+			zap.String("component", "sync"),
+			zap.String("sync", "azblob"),
+		),
+		Interval: interval,
+		Cron:     cron.New(),
+	}, nil
+}
+
 type IK8sClientBuilder interface {
 	GetK8sClient() (dynamic.Interface, error)
 }

core/pkg/sync/builder/syncbuilder_test.go

@@ -197,6 +197,8 @@ func Test_SyncsFromFromConfig(t *testing.T) {
 		{
 			name: "combined",
 			injectFunc: func(builder *SyncBuilder) {
+				t.Setenv("AZURE_STORAGE_ACCOUNT", "myaccount")
+
 				ctrl := gomock.NewController(t)
 
 				mockClientBuilder := buildermock.NewMockIK8sClientBuilder(ctrl)
@@ -236,6 +238,10 @@ func Test_SyncsFromFromConfig(t *testing.T) {
 						URI:      "gs://bucket/path/to/file",
 						Provider: syncProviderGcs,
 					},
+					{
+						URI:      "azblob://bucket/path/to/file",
+						Provider: syncProviderAzblob,
+					},
 				},
 			},
 			wantSyncs: []sync.ISync{
@@ -245,6 +251,7 @@ func Test_SyncsFromFromConfig(t *testing.T) {
 				&file.Sync{},
 				&kubernetes.Sync{},
 				&blob.Sync{},
+				&blob.Sync{},
 			},
 			wantErr: false,
 		},
@@ -324,3 +331,90 @@ func Test_GcsConfig(t *testing.T) {
 		})
 	}
 }
+
+func Test_AzblobConfig(t *testing.T) {
+	lg := logger.NewLogger(nil, false)
+	defaultInterval := uint32(5)
+	tests := []struct {
+		name             string
+		uri              string
+		interval         uint32
+		storageAccount   string
+		expectedBucket   string
+		expectedObject   string
+		expectedInterval uint32
+		wantErr          bool
+	}{
+		{
+			name:             "simple path",
+			uri:              "azblob://bucket/path/to/object",
+			interval:         10,
+			storageAccount:   "myaccount",
+			expectedBucket:   "azblob://bucket/",
+			expectedObject:   "path/to/object",
+			expectedInterval: 10,
+			wantErr:          false,
+		},
+		{
+			name:             "default interval",
+			uri:              "azblob://bucket/path/to/object",
+			storageAccount:   "myaccount",
+			expectedBucket:   "azblob://bucket/",
+			expectedObject:   "path/to/object",
+			expectedInterval: defaultInterval,
+			wantErr:          false,
+		},
+		{
+			name:             "no object set", // Blob syncer will return error when fetching
+			uri:              "azblob://bucket/",
+			storageAccount:   "myaccount",
+			expectedBucket:   "azblob://bucket/",
+			expectedObject:   "",
+			expectedInterval: defaultInterval,
+			wantErr:          false,
+		},
+		{
+			name:             "malformed uri", // Blob syncer will return error when opening bucket
+			uri:              "malformed",
+			storageAccount:   "myaccount",
+			expectedBucket:   "",
+			expectedObject:   "malformed",
+			expectedInterval: defaultInterval,
+			wantErr:          false,
+		},
+		{
+			name:           "storage account not set", // Sync builder will fail and return error
+			uri:            "azblob://bucket/path/to/object",
+			storageAccount: "",
+			wantErr:        true,
+		},
+		{
+			name:           "storage account contains whitespace", // Sync builder will fail and return error
+			uri:            "azblob://bucket/path/to/object",
+			storageAccount: "my account",
+			wantErr:        true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("AZURE_STORAGE_ACCOUNT", tt.storageAccount)
+			azblobSync, err := NewSyncBuilder().newAzblob(sync.SourceConfig{
+				URI:      tt.uri,
+				Interval: tt.interval,
+			}, lg)
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("newAzblob() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			if (err != nil) && (tt.wantErr == true) {
+				return
+			}
+
+			require.Equal(t, tt.expectedBucket, azblobSync.Bucket)
+			require.Equal(t, tt.expectedObject, azblobSync.Object)
+			require.Equal(t, int(tt.expectedInterval), int(azblobSync.Interval))
+		})
+	}
+}

core/pkg/sync/builder/utils.go

@@ -74,9 +74,14 @@ func ParseSyncProviderURIs(uris []string) ([]sync.SourceConfig, error) {
 				URI:      uri,
 				Provider: syncProviderGcs,
 			})
+		case regAzblob.Match(uriB):
+			syncProvidersParsed = append(syncProvidersParsed, sync.SourceConfig{
+				URI:      uri,
+				Provider: syncProviderAzblob,
+			})
 		default:
 			return syncProvidersParsed, fmt.Errorf("invalid sync uri argument: %s, must start with 'file:', "+
-				"'http(s)://', 'grpc(s)://', 'gs://' or 'core.openfeature.dev'", uri)
+				"'http(s)://', 'grpc(s)://', 'gs://', 'azblob://' or 'core.openfeature.dev'", uri)
 		}
 	}
 	return syncProvidersParsed, nil

core/pkg/sync/builder/utils_test.go

@@ -29,7 +29,8 @@ func TestParseSource(t *testing.T) {
 					{"uri":"http://test.com","provider":"http","bearerToken":":)"},
 					{"uri":"host:port","provider":"grpc"},
 					{"uri":"default/my-crd","provider":"kubernetes"},
-					{"uri":"gs://bucket-name/path/to/file","provider":"gcs"}
+					{"uri":"gs://bucket-name/path/to/file","provider":"gcs"},
+					{"uri":"azblob://bucket-name/path/to/file","provider":"azblob"}
 				]`,
 			expectErr: false,
 			out: []sync.SourceConfig{
@@ -54,6 +55,10 @@ func TestParseSource(t *testing.T) {
 					URI:      "gs://bucket-name/path/to/file",
 					Provider: syncProviderGcs,
 				},
+				{
+					URI:      "azblob://bucket-name/path/to/file",
+					Provider: syncProviderAzblob,
+				},
 			},
 		},
 		"multiple-syncs-with-options": {
@@ -188,6 +193,7 @@ func TestParseSyncProviderURIs(t *testing.T) {
 				"grpcs://secure-grpc",
 				"core.openfeature.dev/default/my-crd",
 				"gs://bucket-name/path/to/file",
+				"azblob://bucket-name/path/to/file",
 			},
 			expectErr: false,
 			out: []sync.SourceConfig{
@@ -217,6 +223,10 @@ func TestParseSyncProviderURIs(t *testing.T) {
 					URI:      "gs://bucket-name/path/to/file",
 					Provider: syncProviderGcs,
 				},
+				{
+					URI:      "azblob://bucket-name/path/to/file",
+					Provider: syncProviderAzblob,
+				},
 			},
 		},
 		"empty": {

docs/concepts/syncs.md

@@ -72,7 +72,7 @@ See [sync source](../reference/sync-configuration.md#source-configuration) confi
 
 ### GCS sync
 
-The GCS sync provider fetches flags from a GCS blob and periodically poll the GCS for the flag definition updates.
+The GCS sync provider fetches flags from a GCS blob and periodically polls the GCS for the flag definition updates.
 It uses [application default credentials](https://cloud.google.com/docs/authentication/application-default-credentials) if they
 are [configured](https://cloud.google.com/docs/authentication/provide-credentials-adc) to authorize the calls to GCS.
 
@@ -85,6 +85,22 @@ In this example, `gs://my-bucket/my-flags.json` is expected to be a valid GCS UR
 The polling interval can be configured.
 See [sync source](../reference/sync-configuration.md#source-configuration) configuration for details.
 
+### Azure Blob sync
+
+The Azure Blob sync provider fetches flags from an Azure Blob Storage blob and periodically polls the blob for the flag definition updates.
+It uses [environment variables](https://pkg.go.dev/gocloud.dev/blob/azureblob#hdr-URLs) to set the Storage Account name and to
+authorize the calls to Azure Blob Storage.
+
+```shell
+flagd start --uri azblob://my-container/my-flags.json
+```
+
+In this example, assuming the environment variable AZURE_STORAGE_ACCOUNT is set to `myaccount`, and other options are not set, the service URL will be:
+`https://myaccount.blob.core.windows.net/my-container/my-flags.json`.
+This is expected be a valid service URL accessible by flagd (either by being public or together with environment variable credentials).
+The polling interval can be configured.
+See [sync source](../reference/sync-configuration.md#source-configuration) configuration for details.
+
 ## Merging
 
 Flagd can be configured to read from multiple sources at once, when this is the case flagd will merge all flag definition into a single

docs/reference/flagd-cli/flagd_start.md

@@ -28,7 +28,7 @@ flagd start [flags]
   -d, --socket-path string              Flagd socket path. With grpc the service will become available on this address. With http(s) the grpc-gateway proxy will use this address internally.
   -s, --sources string                  JSON representation of an array of SourceConfig objects. This object contains 2 required fields, uri (string) and provider (string). Documentation for this object: https://flagd.dev/reference/sync-configuration/#source-configuration
   -g, --sync-port int32                 gRPC Sync port (default 8015)
-  -f, --uri .yaml/.yml/.json            Set a sync provider uri to read data from, this can be a filepath, URL (HTTP and gRPC) or FeatureFlag custom resource. When flag keys are duplicated across multiple providers the merge priority follows the index of the flag arguments, as such flags from the uri at index 0 take the lowest precedence, with duplicated keys being overwritten by those from the uri at index 1. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
+  -f, --uri .yaml/.yml/.json            Set a sync provider uri to read data from, this can be a filepath, URL (HTTP and gRPC), FeatureFlag custom resource, or GCS or Azure Blob. When flag keys are duplicated across multiple providers the merge priority follows the index of the flag arguments, as such flags from the uri at index 0 take the lowest precedence, with duplicated keys being overwritten by those from the uri at index 1. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
 ```
 
 ### Options inherited from parent commands