Adding convertAzureError to handle azure errors and return os.ErrNotExist

Author: ptasker

backends/azure/azure.go

@@ -250,13 +250,9 @@ func (b *Backend) List(ctx context.Context, prefix string) (blobList simpleblob.
 	// So we're using the raw marker name here.
 	m, err := b.Load(ctx, UpdateMarkerFilename)
 
-	var notFound bool
+	notFound := errors.Is(err, os.ErrNotExist)
 
-	if err != nil {
-		notFound = bloberror.HasCode(err, bloberror.BlobNotFound)
-	}
-
-	if err != nil && notFound {
+	if err != nil && !notFound {
 		return nil, err
 	}
 
@@ -288,6 +284,23 @@ func (b *Backend) List(ctx context.Context, prefix string) (blobList simpleblob.
 	return blobs.WithPrefix(prefix), nil
 }
 
+// convertAzureError takes an error from Azure SDK and converts it to
+// os.ErrNotExist when appropriate (BlobNotFound, ContainerNotFound, ResourceNotFound).
+// If the error is not a "not found" error, it is returned as is.
+func convertAzureError(err error) error {
+	if err == nil {
+		return nil
+	}
+	if bloberror.HasCode(err,
+		bloberror.BlobNotFound,
+		bloberror.ContainerNotFound,
+		bloberror.ResourceNotFound,
+	) {
+		return fmt.Errorf("%w: %s", os.ErrNotExist, err.Error())
+	}
+	return err
+}
+
 func (b *Backend) doList(ctx context.Context, prefix string) (simpleblob.BlobList, error) {
 	var blobs simpleblob.BlobList
 
@@ -364,7 +377,8 @@ func (b *Backend) doLoadReader(ctx context.Context, name string) (io.ReadCloser,
 
 	// Download the blob's contents and ensure that the download worked properly
 	blobDownloadResponse, err := b.client.DownloadStream(ctx, b.opt.Container, name, nil)
-	if err != nil {
+	if err = convertAzureError(err); err != nil {
+		metricCallErrors.WithLabelValues("load").Inc()
 		return nil, err
 	}
 
@@ -435,12 +449,16 @@ func (b *Backend) doDelete(ctx context.Context, name string) error {
 
 	_, err := b.client.DeleteBlob(ctx, b.opt.Container, name, nil)
 
-	if err != nil {
+	if err = convertAzureError(err); err != nil {
+		// Delete is idempotent - if blob doesn't exist, that's fine
+		if errors.Is(err, os.ErrNotExist) {
+			return nil
+		}
 		metricCallErrors.WithLabelValues("delete").Inc()
 		return err
 	}
 
-	return err
+	return nil
 }
 
 // setGlobalPrefix updates the global prefix in b and the cached marker name,

backends/azure/azure_test.go

@@ -112,7 +112,7 @@ func TestBackend(t *testing.T) {
 	defer tearDown()
 
 	b := getBackend(ctx, t)
-	tester.DoBackendTestsAzure(t, b)
+	tester.DoBackendTests(t, b)
 	assert.Len(t, b.lastMarker, 0)
 }
 
@@ -124,7 +124,7 @@ func TestBackend_marker(t *testing.T) {
 	b := getBackend(ctx, t)
 	b.opt.UseUpdateMarker = true
 
-	tester.DoBackendTestsAzure(t, b)
+	tester.DoBackendTests(t, b)
 	assert.Regexp(t, "^foo-1:[A-Za-z0-9]*:[0-9]+:true$", b.lastMarker)
 	// ^ reflects last write operation of tester.DoBackendTestsAzure
 	//   i.e. deleting "foo-1"
@@ -143,7 +143,7 @@ func TestBackend_globalprefix(t *testing.T) {
 	b := getBackend(ctx, t)
 	b.setGlobalPrefix("v5/")
 
-	tester.DoBackendTestsAzure(t, b)
+	tester.DoBackendTests(t, b)
 	assert.Empty(t, b.lastMarker)
 }
 
@@ -157,6 +157,6 @@ func TestBackend_globalPrefixAndMarker(t *testing.T) {
 	b.setGlobalPrefix("v6/")
 	b.opt.UseUpdateMarker = true
 
-	tester.DoBackendTestsAzure(t, b)
+	tester.DoBackendTests(t, b)
 	assert.NotEmpty(t, b.lastMarker)
 }

backends/azure/stream_test.go

@@ -3,7 +3,9 @@ package azure
 import (
 	"bytes"
 	"context"
+	"errors"
 	"io"
+	"os"
 	"testing"
 	"time"
 
@@ -21,7 +23,7 @@ func TestStreamReader(t *testing.T) {
 	reader, err := b.NewReader(ctx, "does-not-exist")
 	assert.Error(t, err)
 	assert.Nil(t, reader)
-	assert.ErrorContains(t, err, "BlobNotFound")
+	assert.True(t, errors.Is(err, os.ErrNotExist), "expected os.ErrNotExist")
 
 	// Store test data
 	testData := []byte("test data for streaming")
@@ -73,7 +75,7 @@ func TestStreamWriter(t *testing.T) {
 	// File should not exist before closing
 	_, err = b.Load(ctx, "test-stream-write")
 	assert.Error(t, err)
-	assert.ErrorContains(t, err, "BlobNotFound")
+	assert.True(t, errors.Is(err, os.ErrNotExist), "expected os.ErrNotExist")
 
 	// Close to finalize the upload
 	err = writer.Close()