feat(spanner): add database roles (#5701)

* feat(spanner): add database roles

* tests

* make tests pass

* respond to PR comments

* add test for ListDatabaseRoles

* skip emulator tests

* Add check for nil

Co-authored-by: rahul2393 <rahulyadavsep92@gmail.com>
Co-authored-by: rahul2393 <irahul@google.com>

spanner/client.go

@@ -143,6 +143,10 @@ type ClientConfig struct {
 	// Recommended format: ``application-or-tool-ID/major.minor.version``.
 	UserAgent string
 
+	// DatabaseRole specifies the role to be assumed for all operations on the
+	// database by this client.
+	DatabaseRole string
+
 	// Logger is the logger to use for this client. If it is nil, all logging
 	// will be directed to the standard logger.
 	Logger *log.Logger
@@ -220,7 +224,7 @@ func NewClientWithConfig(ctx context.Context, database string, config ClientConf
 		config.incStep = DefaultSessionPoolConfig.incStep
 	}
 	// Create a session client.
-	sc := newSessionClient(pool, database, config.UserAgent, sessionLabels, metadata.Pairs(resourcePrefixHeader, database), config.Logger, config.CallOptions)
+	sc := newSessionClient(pool, database, config.UserAgent, sessionLabels, config.DatabaseRole, metadata.Pairs(resourcePrefixHeader, database), config.Logger, config.CallOptions)
 	// Create a session pool.
 	config.SessionPoolConfig.sessionLabels = sessionLabels
 	sp, err := newSessionPool(sc, config.SessionPoolConfig)

spanner/client_test.go

@@ -1146,6 +1146,35 @@ func TestClient_ReadWriteTransaction_DoNotLeakSessionOnPanic(t *testing.T) {
 	}
 }
 
+func TestClient_SessionContainsDatabaseRole(t *testing.T) {
+	// Make sure that there is always only one session in the pool.
+	sc := SessionPoolConfig{
+		MinOpened: 1,
+		MaxOpened: 1,
+	}
+	server, client, teardown := setupMockedTestServerWithConfig(t, ClientConfig{SessionPoolConfig: sc, DatabaseRole: "test"})
+	defer teardown()
+
+	// Wait until all sessions have been created, so we know that those requests will not interfere with the test.
+	sp := client.idleSessions
+	waitFor(t, func() error {
+		sp.mu.Lock()
+		defer sp.mu.Unlock()
+		if uint64(sp.idleList.Len()) != 1 {
+			return fmt.Errorf("num open sessions mismatch.\nGot: %d\nWant: %d", sp.numOpened, sp.MinOpened)
+		}
+		return nil
+	})
+
+	resp, err := server.TestSpanner.GetSession(context.Background(), &sppb.GetSessionRequest{Name: client.idleSessions.idleList.Front().Value.(*session).id})
+	if err != nil {
+		t.Fatalf("Failed to get session unexpectedly: %v", err)
+	}
+	if g, w := resp.CreatorRole, "test"; g != w {
+		t.Fatalf("database role mismatch.\nGot: %v\nWant: %v", g, w)
+	}
+}
+
 func TestClient_SessionNotFound(t *testing.T) {
 	// Ensure we always have at least one session in the pool.
 	sc := SessionPoolConfig{