feat(datastore): Multi DB support

CONTRIBUTING.md

@@ -125,6 +125,7 @@ variables:
 bamboo-shift-455) for the general project.
 - `GCLOUD_TESTS_GOLANG_KEY`: The path to the JSON key file of the general
 project's service account.
+- `GCLOUD_TESTS_GOLANG_DATASTORE_DATABASES`: Comma separated list of developer's Datastore databases. If not provided, default database i.e. empty string is used.
 - `GCLOUD_TESTS_GOLANG_FIRESTORE_PROJECT_ID`: Developers Console project's ID
 (e.g. doorway-cliff-677) for the Firestore project.
 - `GCLOUD_TESTS_GOLANG_FIRESTORE_KEY`: The path to the JSON key file of the
@@ -153,8 +154,9 @@ $ gcloud config set project $GCLOUD_TESTS_GOLANG_PROJECT_ID
 # Authenticates the gcloud tool with your account.
 $ gcloud auth login
 
-# Create the indexes used in the datastore integration tests.
-$ gcloud datastore indexes create datastore/testdata/index.yaml
+# Create the indexes for all the databases you want to use in the datastore integration tests. 
+# Use empty string as databaseID or skip database flag for default database.
+$ gcloud alpha datastore indexes create --database=your-databaseID-1 --project=cndb-sdk-golang-general testdata/index.yaml
 
 # Creates a Google Cloud storage bucket with the same name as your test project,
 # and with the Cloud Logging service account as owner, for the sink
@@ -219,6 +221,10 @@ export GCLOUD_TESTS_GOLANG_PROJECT_ID=your-project
 # The path to the JSON key file of the general project's service account.
 export GCLOUD_TESTS_GOLANG_KEY=~/directory/your-project-abcd1234.json
 
+# Comma separated list of developer's Datastore databases. If not provided, 
+# default database i.e. empty string is used.
+export GCLOUD_TESTS_GOLANG_DATASTORE_DATABASES=your-database-1,your-database-2
+
 # Developers Console project's ID (e.g. doorway-cliff-677) for the Firestore project.
 export GCLOUD_TESTS_GOLANG_FIRESTORE_PROJECT_ID=your-firestore-project
 

datastore/client.go

@@ -42,11 +42,15 @@ type datastoreClient struct {
 	md metadata.MD
 }
 
-func newDatastoreClient(conn grpc.ClientConnInterface, projectID string) pb.DatastoreClient {
+func newDatastoreClient(conn grpc.ClientConnInterface, projectID, databaseID string) pb.DatastoreClient {
+	resourcePrefixValue := "projects/" + projectID
+	if databaseID != "" {
+		resourcePrefixValue += "/databases/" + databaseID
+	}
 	return &datastoreClient{
 		c: pb.NewDatastoreClient(conn),
 		md: metadata.Pairs(
-			resourcePrefixHeader, "projects/"+projectID,
+			resourcePrefixHeader, resourcePrefixValue,
 			"x-goog-api-client", fmt.Sprintf("gl-go/%s gccl/%s grpc/", version.Go(), internal.Version)),
 	}
 }

datastore/datastore.go

@@ -53,11 +53,20 @@ const DetectProjectID = "*detect-project-id*"
 // the resource being operated on.
 const resourcePrefixHeader = "google-cloud-resource-prefix"
 
+// DefaultDatabaseID is ID of the default database denoted by an empty string
+const DefaultDatabaseID = ""
+
+var (
+	gtransportDialPoolFn = gtransport.DialPool
+	detectProjectIDFn    = detectProjectID
+)
+
 // Client is a client for reading and writing data in a datastore dataset.
 type Client struct {
 	connPool     gtransport.ConnPool
 	client       pb.DatastoreClient
 	dataset      string // Called dataset by the datastore API, synonym for project ID.
+	databaseID   string // Default value is empty string
 	readSettings *readSettings
 }
 
@@ -69,6 +78,21 @@ type Client struct {
 // NewClient to detect the project ID from the credentials.
 // Call (*Client).Close() when done with the client.
 func NewClient(ctx context.Context, projectID string, opts ...option.ClientOption) (*Client, error) {
+	client, err := NewClientWithDatabase(ctx, projectID, DefaultDatabaseID, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return client, nil
+}
+
+// NewClientWithDatabase creates a new Client for given dataset and database.
+// If the project ID is empty, it is derived from the DATASTORE_PROJECT_ID environment variable.
+// If the DATASTORE_EMULATOR_HOST environment variable is set, client will use
+// its value to connect to a locally-running datastore emulator.
+// DetectProjectID can be passed as the projectID argument to instruct
+// NewClientWithDatabase to detect the project ID from the credentials.
+// Call (*Client).Close() when done with the client.
+func NewClientWithDatabase(ctx context.Context, projectID, databaseID string, opts ...option.ClientOption) (*Client, error) {
 	var o []option.ClientOption
 	// Environment variables for gcd emulator:
 	// https://cloud.google.com/datastore/docs/tools/datastore-emulator
@@ -80,7 +104,7 @@ func NewClient(ctx context.Context, projectID string, opts ...option.ClientOptio
 			option.WithGRPCDialOption(grpc.WithInsecure()),
 		}
 		if projectID == DetectProjectID {
-			projectID, _ = detectProjectID(ctx, opts...)
+			projectID, _ = detectProjectIDFn(ctx, opts...)
 			if projectID == "" {
 				projectID = "dummy-emulator-datastore-project"
 			}
@@ -106,7 +130,7 @@ func NewClient(ctx context.Context, projectID string, opts ...option.ClientOptio
 	o = append(o, opts...)
 
 	if projectID == DetectProjectID {
-		detected, err := detectProjectID(ctx, opts...)
+		detected, err := detectProjectIDFn(ctx, opts...)
 		if err != nil {
 			return nil, err
 		}
@@ -116,15 +140,16 @@ func NewClient(ctx context.Context, projectID string, opts ...option.ClientOptio
 	if projectID == "" {
 		return nil, errors.New("datastore: missing project/dataset id")
 	}
-	connPool, err := gtransport.DialPool(ctx, o...)
+	connPool, err := gtransportDialPoolFn(ctx, o...)
 	if err != nil {
 		return nil, fmt.Errorf("dialing: %w", err)
 	}
 	return &Client{
 		connPool:     connPool,
-		client:       newDatastoreClient(connPool, projectID),
+		client:       newDatastoreClient(connPool, projectID, databaseID),
 		dataset:      projectID,
 		readSettings: &readSettings{},
+		databaseID:   databaseID,
 	}, nil
 }
 
@@ -468,6 +493,7 @@ func (c *Client) get(ctx context.Context, keys []*Key, dst interface{}, opts *pb
 	}
 	req := &pb.LookupRequest{
 		ProjectId:   c.dataset,
+		DatabaseId:  c.databaseID,
 		Keys:        pbKeys,
 		ReadOptions: opts,
 	}
@@ -565,9 +591,10 @@ func (c *Client) PutMulti(ctx context.Context, keys []*Key, src interface{}) (re
 
 	// Make the request.
 	req := &pb.CommitRequest{
-		ProjectId: c.dataset,
-		Mutations: mutations,
-		Mode:      pb.CommitRequest_NON_TRANSACTIONAL,
+		ProjectId:  c.dataset,
+		DatabaseId: c.databaseID,
+		Mutations:  mutations,
+		Mode:       pb.CommitRequest_NON_TRANSACTIONAL,
 	}
 	resp, err := c.client.Commit(ctx, req)
 	if err != nil {
@@ -688,9 +715,10 @@ func (c *Client) DeleteMulti(ctx context.Context, keys []*Key) (err error) {
 	}
 
 	req := &pb.CommitRequest{
-		ProjectId: c.dataset,
-		Mutations: mutations,
-		Mode:      pb.CommitRequest_NON_TRANSACTIONAL,
+		ProjectId:  c.dataset,
+		DatabaseId: c.databaseID,
+		Mutations:  mutations,
+		Mode:       pb.CommitRequest_NON_TRANSACTIONAL,
 	}
 	_, err = c.client.Commit(ctx, req)
 	return err
@@ -740,9 +768,10 @@ func (c *Client) Mutate(ctx context.Context, muts ...*Mutation) (ret []*Key, err
 		return nil, err
 	}
 	req := &pb.CommitRequest{
-		ProjectId: c.dataset,
-		Mutations: pmuts,
-		Mode:      pb.CommitRequest_NON_TRANSACTIONAL,
+		ProjectId:  c.dataset,
+		DatabaseId: c.databaseID,
+		Mutations:  pmuts,
+		Mode:       pb.CommitRequest_NON_TRANSACTIONAL,
 	}
 	resp, err := c.client.Commit(ctx, req)
 	if err != nil {

datastore/datastore_test.go

@@ -24,11 +24,65 @@ import (
 
 	"cloud.google.com/go/internal/testutil"
 	"github.com/google/go-cmp/cmp"
+	"google.golang.org/api/option"
+	"google.golang.org/api/transport/grpc"
 	pb "google.golang.org/genproto/googleapis/datastore/v1"
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
+func TestNewClientWithDatabase(t *testing.T) {
+	origDetectProjectIDFn := detectProjectIDFn
+	origGtransportDialPoolFn := gtransportDialPoolFn
+	defer func() {
+		detectProjectIDFn = origDetectProjectIDFn
+		gtransportDialPoolFn = origGtransportDialPoolFn
+	}()
+
+	tests := []struct {
+		desc                 string
+		databaseID           string
+		wantErr              bool
+		detectProjectIDFn    func(ctx context.Context, opts ...option.ClientOption) (string, error)
+		gtransportDialPoolFn func(ctx context.Context, opts ...option.ClientOption) (grpc.ConnPool, error)
+	}{
+		{
+			desc:       "Error from detect project ID should not fail NewClientWithDatabase",
+			databaseID: "db1",
+			wantErr:    false,
+			detectProjectIDFn: func(ctx context.Context, opts ...option.ClientOption) (string, error) {
+				return "", errors.New("mock error from detect project ID")
+			},
+			gtransportDialPoolFn: origGtransportDialPoolFn,
+		},
+		{
+			desc:              "Error from DialPool",
+			databaseID:        "db1",
+			wantErr:           true,
+			detectProjectIDFn: origDetectProjectIDFn,
+			gtransportDialPoolFn: func(ctx context.Context, opts ...option.ClientOption) (grpc.ConnPool, error) {
+				return nil, errors.New("mock error from DialPool")
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			detectProjectIDFn = tc.detectProjectIDFn
+			gtransportDialPoolFn = tc.gtransportDialPoolFn
+
+			client, gotErr := NewClientWithDatabase(context.Background(), "my-project", tc.databaseID)
+			if gotErr != nil && !tc.wantErr {
+				t.Errorf("got error %v, but none was expected", gotErr)
+			} else if gotErr == nil && tc.wantErr {
+				t.Errorf("wanted error, but none returned")
+			} else if gotErr == nil && client.databaseID != tc.databaseID {
+				t.Errorf("got %s, want %s", client.databaseID, tc.databaseID)
+			}
+		})
+	}
+}
+
 func TestQueryConstruction(t *testing.T) {
 	tests := []struct {
 		q, exp *Query

datastore/integration_test.go

@@ -49,7 +49,10 @@ var timeNow = time.Now()
 // when the tests are run in parallel.
 var suffix string
 
-const replayFilename = "datastore.replay"
+const (
+	replayFilename = "datastore.replay"
+	envDatabases   = "GCLOUD_TESTS_GOLANG_DATASTORE_DATABASES"
+)
 
 type replayInfo struct {
 	ProjectID string
@@ -62,6 +65,7 @@ var (
 	newTestClient = func(ctx context.Context, t *testing.T) *Client {
 		return newClient(ctx, t, nil)
 	}
+	testParams map[string]interface{}
 )
 
 func TestMain(m *testing.M) {
@@ -103,7 +107,25 @@ func testMain(m *testing.M) int {
 		log.Printf("recording to %s", replayFilename)
 	}
 	suffix = fmt.Sprintf("-t%d", timeNow.UnixNano())
-	return m.Run()
+
+	// Run tests on multiple databases
+	databasesStr, ok := os.LookupEnv(envDatabases)
+	if !ok {
+		databasesStr = ""
+	}
+	databaseIDs := strings.Split(databasesStr, ",")
+	testParams = make(map[string]interface{})
+
+	for _, databaseID := range databaseIDs {
+		log.Printf("Setting up tests to run on databaseID: %q\n", databaseID)
+		testParams["databaseID"] = databaseID
+		status := m.Run()
+		if status != 0 {
+			return status
+		}
+	}
+
+	return 0
 }
 
 func initReplay() {
@@ -133,9 +155,9 @@ func initReplay() {
 		}
 
 		opts := append(grpcHeadersEnforcer.CallOptions(), option.WithGRPCConn(conn))
-		client, err := NewClient(ctx, ri.ProjectID, opts...)
+		client, err := NewClientWithDatabase(ctx, ri.ProjectID, testParams["databaseID"].(string), opts...)
 		if err != nil {
-			t.Fatalf("NewClient: %v", err)
+			t.Fatalf("NewClientWithDatabase: %v", err)
 		}
 		return client
 	}
@@ -161,13 +183,27 @@ func newClient(ctx context.Context, t *testing.T, dialOpts []grpc.DialOption) *C
 	for _, opt := range dialOpts {
 		opts = append(opts, option.WithGRPCDialOption(opt))
 	}
-	client, err := NewClient(ctx, testutil.ProjID(), opts...)
+	client, err := NewClientWithDatabase(ctx, testutil.ProjID(), testParams["databaseID"].(string), opts...)
 	if err != nil {
-		t.Fatalf("NewClient: %v", err)
+		t.Fatalf("NewClientWithDatabase: %v", err)
 	}
 	return client
 }
 
+func TestIntegration_NewClient(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Integration tests skipped in short mode")
+	}
+	ctx := context.Background()
+	client, err := NewClient(ctx, testutil.ProjID())
+	if err != nil {
+		t.Fatalf("NewClient: %v", err)
+	}
+	if client.databaseID != DefaultDatabaseID {
+		t.Fatalf("NewClient: got %s, want %s", client.databaseID, DefaultDatabaseID)
+	}
+}
+
 func TestIntegration_Basics(t *testing.T) {
 	ctx, _ := context.WithTimeout(context.Background(), time.Second*20)
 	client := newTestClient(ctx, t)
@@ -1487,13 +1523,13 @@ func TestIntegration_DetectProjectID(t *testing.T) {
 	}
 
 	// Use creds with project ID.
-	if _, err := NewClient(ctx, DetectProjectID, option.WithCredentials(creds)); err != nil {
-		t.Errorf("NewClient: %v", err)
+	if _, err := NewClientWithDatabase(ctx, DetectProjectID, testParams["databaseID"].(string), option.WithCredentials(creds)); err != nil {
+		t.Errorf("NewClientWithDatabase: %v", err)
 	}
 
 	ts := testutil.ErroringTokenSource{}
 	// Try to use creds without project ID.
-	_, err := NewClient(ctx, DetectProjectID, option.WithTokenSource(ts))
+	_, err := NewClientWithDatabase(ctx, DetectProjectID, testParams["databaseID"].(string), option.WithTokenSource(ts))
 	if err == nil || err.Error() != "datastore: see the docs on DetectProjectID" {
 		t.Errorf("expected an error while using TokenSource that does not have a project ID")
 	}

datastore/key.go

@@ -247,8 +247,9 @@ func (c *Client) AllocateIDs(ctx context.Context, keys []*Key) ([]*Key, error) {
 	}
 
 	req := &pb.AllocateIdsRequest{
-		ProjectId: c.dataset,
-		Keys:      multiKeyToProto(keys),
+		ProjectId:  c.dataset,
+		DatabaseId: c.databaseID,
+		Keys:       multiKeyToProto(keys),
 	}
 	resp, err := c.client.AllocateIds(ctx, req)
 	if err != nil {

datastore/query.go

@@ -727,7 +727,8 @@ func (c *Client) Run(ctx context.Context, q *Query) *Iterator {
 		pageCursor:   q.start,
 		entityCursor: q.start,
 		req: &pb.RunQueryRequest{
-			ProjectId: c.dataset,
+			ProjectId:  c.dataset,
+			DatabaseId: c.databaseID,
 		},
 	}
 
@@ -766,7 +767,8 @@ func (c *Client) RunAggregationQuery(ctx context.Context, aq *AggregationQuery)
 	}
 
 	req := &pb.RunAggregationQueryRequest{
-		ProjectId: c.dataset,
+		ProjectId:  c.dataset,
+		DatabaseId: c.databaseID,
 		QueryType: &pb.RunAggregationQueryRequest_AggregationQuery{
 			AggregationQuery: &pb.AggregationQuery{
 				QueryType: &pb.AggregationQuery_NestedQuery{