Merge pull request #2025 from josephschorr/pg-readonly-error

Add nicer error if the Postgres primary node has gone readonly

internal/datastore/common/errors.go

@@ -44,6 +44,31 @@ func NewSerializationError(err error) error {
 	return SerializationError{err}
 }
 
+// ReadOnlyTransactionError is returned when an otherwise read-write
+// transaction fails on writes with an error indicating that the datastore
+// is currently in a read-only mode.
+type ReadOnlyTransactionError struct {
+	error
+}
+
+func (err ReadOnlyTransactionError) GRPCStatus() *status.Status {
+	return spiceerrors.WithCodeAndDetails(
+		err,
+		codes.Aborted,
+		spiceerrors.ForReason(
+			v1.ErrorReason_ERROR_REASON_SERVICE_READ_ONLY,
+			map[string]string{},
+		),
+	)
+}
+
+// NewReadOnlyTransactionError creates a new ReadOnlyTransactionError.
+func NewReadOnlyTransactionError(err error) error {
+	return ReadOnlyTransactionError{
+		fmt.Errorf("could not perform write operation, as the datastore is currently in read-only mode: %w. This may indicate that the datastore has been put into maintenance mode", err),
+	}
+}
+
 // CreateRelationshipExistsError is an error returned when attempting to CREATE an already-existing
 // relationship.
 type CreateRelationshipExistsError struct {

internal/datastore/postgres/common/errors.go

@@ -16,6 +16,7 @@ const (
 	pgUniqueConstraintViolation = "23505"
 	pgSerializationFailure      = "40001"
 	pgTransactionAborted        = "25P02"
+	pgReadOnlyTransaction       = "25006"
 )
 
 var (
@@ -30,6 +31,13 @@ func IsConstraintFailureError(err error) bool {
 	return errors.As(err, &pgerr) && pgerr.Code == pgUniqueConstraintViolation
 }
 
+// IsReadOnlyTransactionError returns true if the error is a Postgres error indicating a read-only
+// transaction.
+func IsReadOnlyTransactionError(err error) bool {
+	var pgerr *pgconn.PgError
+	return errors.As(err, &pgerr) && pgerr.Code == pgReadOnlyTransaction
+}
+
 // ConvertToWriteConstraintError converts the given Postgres error into a CreateRelationshipExistsError
 // if applicable. If not applicable, returns nils.
 func ConvertToWriteConstraintError(livingTupleConstraints []string, err error) error {

internal/datastore/postgres/postgres.go

@@ -584,6 +584,10 @@ func wrapError(err error) error {
 		return common.NewSerializationError(err)
 	}
 
+	if pgxcommon.IsReadOnlyTransactionError(err) {
+		return common.NewReadOnlyTransactionError(err)
+	}
+
 	// hack: pgx asyncClose usually happens after cancellation,
 	// but the reason for it being closed is not propagated
 	// and all we get is attempting to perform an operation