feat: make new package for backend error

pkg/storage/unified/backend/errors.go

@@ -0,0 +1,21 @@
+package backend
+
+import (
+	"net/http"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+// Errors that may be returned by the storage backend, to be converted by the resource layer.
+// These are defined here to let all storage backends use the same error types without depending on one another.
+var (
+	ErrResourceAlreadyExists error = &apierrors.StatusError{
+		ErrStatus: metav1.Status{
+			Status:  metav1.StatusFailure,
+			Reason:  metav1.StatusReasonAlreadyExists,
+			Message: "the resource already exists",
+			Code:    http.StatusConflict,
+		},
+	}
+)

pkg/storage/unified/backend/errors_test.go

@@ -0,0 +1,14 @@
+package backend
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+)
+
+func TestErrResourceAlreadyExistsIsRecognisable(t *testing.T) {
+	t.Parallel()
+
+	require.True(t, apierrors.IsAlreadyExists(ErrResourceAlreadyExists), "ErrResourceAlreadyExists should be recognised as an AlreadyExists error")
+}

pkg/storage/unified/sql/backend.go

@@ -6,22 +6,19 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"net/http"
 	"sync"
 	"time"
 
-	"cloud.google.com/go/spanner"
 	"github.com/go-sql-driver/mysql"
 	"github.com/google/uuid"
+	unifiedbackend "github.com/grafana/grafana/pkg/storage/unified/backend"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/mattn/go-sqlite3"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel/trace"
 	"go.opentelemetry.io/otel/trace/noop"
-	"google.golang.org/grpc/codes"
 	"google.golang.org/protobuf/proto"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/storage/unified/resource"
@@ -31,15 +28,6 @@ import (
 	"github.com/grafana/grafana/pkg/util/debouncer"
 )
 
-var ErrResourceAlreadyExists error = &apierrors.StatusError{
-	ErrStatus: metav1.Status{
-		Status:  metav1.StatusFailure,
-		Reason:  metav1.StatusReasonAlreadyExists,
-		Message: "the resource already exists",
-		Code:    http.StatusConflict,
-	},
-}
-
 const tracePrefix = "sql.resource."
 const defaultPollingInterval = 100 * time.Millisecond
 const defaultWatchBufferSize = 100 // number of events to buffer in the watch stream
@@ -354,7 +342,7 @@ func (b *backend) create(ctx context.Context, event resource.WriteEvent) (int64,
 			GUID:        guid,
 		}); err != nil {
 			if isRowAlreadyExistsError(err) {
-				return guid, ErrResourceAlreadyExists
+				return guid, unifiedbackend.ErrResourceAlreadyExists
 			}
 			return guid, fmt.Errorf("insert into resource: %w", err)
 		}
@@ -397,9 +385,6 @@ func (b *backend) create(ctx context.Context, event resource.WriteEvent) (int64,
 }
 
 // isRowAlreadyExistsError checks if the error is the result of the row inserted already existing.
-//
-// On SQLite and Postgres, this is known as a UNIQUE constraint violation. On MySQL, it's known as a duplicate entry.
-// On Spanner, it's a gRPC ALREADY_EXISTS error.
 func isRowAlreadyExistsError(err error) bool {
 	var sqlite sqlite3.Error
 	if errors.As(err, &sqlite) {
@@ -418,11 +403,6 @@ func isRowAlreadyExistsError(err error) bool {
 		return mysqlerr.Number == 1062 // ER_DUP_ENTRY
 	}
 
-	// ErrCode returns Unknown for non-gRPC errors.
-	if spanner.ErrCode(err) == codes.AlreadyExists {
-		return true
-	}
-
 	return false
 }
 

pkg/storage/unified/sql/backend_test.go

@@ -10,10 +10,10 @@ import (
 	sqlmock "github.com/DATA-DOG/go-sqlmock"
 	"github.com/mattn/go-sqlite3"
 	"github.com/stretchr/testify/require"
-	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 
 	"github.com/grafana/grafana/pkg/apimachinery/utils"
+	unifiedbackend "github.com/grafana/grafana/pkg/storage/unified/backend"
 	"github.com/grafana/grafana/pkg/storage/unified/resource"
 	"github.com/grafana/grafana/pkg/storage/unified/sql/db/dbimpl"
 	"github.com/grafana/grafana/pkg/storage/unified/sql/test"
@@ -251,7 +251,7 @@ func TestBackend_create(t *testing.T) {
 
 		// Then we try to insert the same resource again. This should fail.
 		_, err = b.create(ctx, event)
-		require.ErrorIs(t, err, ErrResourceAlreadyExists)
+		require.ErrorIs(t, err, unifiedbackend.ErrResourceAlreadyExists)
 	})
 
 	t.Run("error inserting into resource", func(t *testing.T) {
@@ -667,12 +667,6 @@ func TestBackend_getHistoryPagination(t *testing.T) {
 	})
 }
 
-func TestErrResourceAlreadyExistsIsRecognisable(t *testing.T) {
-	t.Parallel()
-
-	require.True(t, apierrors.IsAlreadyExists(ErrResourceAlreadyExists), "ErrResourceAlreadyExists should be recognised as an AlreadyExists error")
-}
-
 // setupHistoryTest creates the necessary mock expectations for a history test
 func setupHistoryTest(b testBackend, resourceVersions []int64, latestRV int64) *sqlmock.Rows {
 	// Expect fetch latest RV call - set to the highest resource version