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fix: prevent compactor from deleting blocks on transient upload failures #8554

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fix: prevent compactor from deleting blocks on transient upload failures #8554

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8f782cb
fix: clean up partial block uploads on failure
shivansh-gohem Nov 7, 2025
bf42379
docs: acknowledge external broken links causing doc check failure
shivansh-gohem Nov 7, 2025
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22 changes: 21 additions & 1 deletion pkg/block/block.go
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Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,7 @@ func UploadPromBlock(ctx context.Context, logger log.Logger, bkt objstore.Bucket
// It makes sure cleanup is done on error to avoid partial block uploads.
// TODO(bplotka): Ensure bucket operations have reasonable backoff retries.
// NOTE: Upload updates `meta.Thanos.File` section.
func upload(ctx context.Context, logger log.Logger, bkt objstore.Bucket, bdir string, hf metadata.HashFunc, checkExternalLabels bool, options ...objstore.UploadOption) error {
func upload(ctx context.Context, logger log.Logger, bkt objstore.Bucket, bdir string, hf metadata.HashFunc, checkExternalLabels bool, options ...objstore.UploadOption) (err error) {
df, err := os.Stat(bdir)
if err != nil {
return err
Expand Down Expand Up @@ -141,6 +141,26 @@ func upload(ctx context.Context, logger log.Logger, bkt objstore.Bucket, bdir st
return errors.Wrap(err, "gather meta file stats")
}

// Track if we started uploading so we can clean up on failure.
// We only clean up if upload started but failed, to avoid partial blocks in object storage.
uploadStarted := false
defer func() {
if err != nil && uploadStarted {
// Upload failed after we started - clean up partial block from object storage.
level.Warn(logger).Log("msg", "upload failed, cleaning up partial block from object storage", "block", id, "err", err)

// Use a new context since the original might be canceled/timed out.
cleanupCtx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
defer cancel()

if deleteErr := Delete(cleanupCtx, logger, bkt, id); deleteErr != nil {
level.Error(logger).Log("msg", "failed to clean up partial block after upload failure", "block", id, "err", deleteErr)
}
}
}()

uploadStarted = true

if err := objstore.UploadDir(ctx, logger, bkt, filepath.Join(bdir, ChunksDirname), path.Join(id.String(), ChunksDirname), options...); err != nil {
return errors.Wrap(err, "upload chunks")
}
Expand Down
45 changes: 20 additions & 25 deletions pkg/block/block_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"os"
"path"
Expand Down Expand Up @@ -466,7 +465,7 @@ func TestHashDownload(t *testing.T) {
err = Download(ctx, log.NewNopLogger(), instrumentedBkt, m.ULID, path.Join(tmpDir, b1.String()))
testutil.Ok(t, err)
testutil.Ok(t, promtest.GatherAndCompare(r, strings.NewReader(`
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# TYPE thanos_objstore_bucket_operations_total counter
thanos_objstore_bucket_operations_total{bucket="test",operation="attributes"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="delete"} 0
Expand All @@ -475,7 +474,7 @@ func TestHashDownload(t *testing.T) {
thanos_objstore_bucket_operations_total{bucket="test",operation="get_range"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="iter"} 2
thanos_objstore_bucket_operations_total{bucket="test",operation="upload"} 3
`), `thanos_objstore_bucket_operations_total`))
`), `thanos_objstore_bucket_operations_total`))
}

// Ensures that we always download MetaFile.
Expand All @@ -484,7 +483,7 @@ func TestHashDownload(t *testing.T) {
err = Download(ctx, log.NewNopLogger(), instrumentedBkt, m.ULID, path.Join(tmpDir, b1.String()))
testutil.Ok(t, err)
testutil.Ok(t, promtest.GatherAndCompare(r, strings.NewReader(`
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# TYPE thanos_objstore_bucket_operations_total counter
thanos_objstore_bucket_operations_total{bucket="test",operation="attributes"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="delete"} 0
Expand All @@ -493,7 +492,7 @@ func TestHashDownload(t *testing.T) {
thanos_objstore_bucket_operations_total{bucket="test",operation="get_range"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="iter"} 4
thanos_objstore_bucket_operations_total{bucket="test",operation="upload"} 3
`), `thanos_objstore_bucket_operations_total`))
`), `thanos_objstore_bucket_operations_total`))
}

// Remove chunks => gets redownloaded.
Expand All @@ -504,16 +503,16 @@ func TestHashDownload(t *testing.T) {
err = Download(ctx, log.NewNopLogger(), instrumentedBkt, m.ULID, path.Join(tmpDir, b1.String()))
testutil.Ok(t, err)
testutil.Ok(t, promtest.GatherAndCompare(r, strings.NewReader(`
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# TYPE thanos_objstore_bucket_operations_total counter
thanos_objstore_bucket_operations_total{bucket="test",operation="attributes"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="delete"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="exists"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="get"} 7
thanos_objstore_bucket_operations_total{bucket="test",operation="get_range"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="iter"} 6
thanos_objstore_bucket_operations_total{bucket="test",operation="upload"} 3
`), `thanos_objstore_bucket_operations_total`))
# HELP thanos_objstore_bucket_operations_total Total number of all attempted operations against a bucket.
# TYPE thanos_objstore_bucket_operations_total counter
thanos_objstore_bucket_operations_total{bucket="test",operation="attributes"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="delete"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="exists"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="get"} 7
thanos_objstore_bucket_operations_total{bucket="test",operation="get_range"} 0
thanos_objstore_bucket_operations_total{bucket="test",operation="iter"} 6
thanos_objstore_bucket_operations_total{bucket="test",operation="upload"} 3
`), `thanos_objstore_bucket_operations_total`))
}
}

Expand All @@ -540,10 +539,9 @@ func TestUploadCleanup(t *testing.T) {
uploadErr := Upload(ctx, log.NewNopLogger(), errBkt, path.Join(tmpDir, b1.String()), metadata.NoneFunc)
testutil.Assert(t, errors.Is(uploadErr, errUploadFailed))

// If upload of index fails, the objects remain because the deletion of partial blocks
// is taken care of by the Compactor.
testutil.Equals(t, 2, len(bkt.Objects()))
testutil.Assert(t, len(bkt.Objects()[path.Join(DebugMetas, fmt.Sprintf("%s.json", b1.String()))]) == 0)
// If upload of index fails, the partial upload is cleaned up from object storage.
// This ensures no partial blocks are left behind.
testutil.Equals(t, 0, len(bkt.Objects()))
}

{
Expand All @@ -552,12 +550,9 @@ func TestUploadCleanup(t *testing.T) {
uploadErr := Upload(ctx, log.NewNopLogger(), errBkt, path.Join(tmpDir, b1.String()), metadata.NoneFunc)
testutil.Assert(t, errors.Is(uploadErr, errUploadFailed))

// If upload of meta.json fails, nothing is cleaned up.
testutil.Equals(t, 3, len(bkt.Objects()))
testutil.Assert(t, len(bkt.Objects()[path.Join(b1.String(), ChunksDirname, "000001")]) > 0)
testutil.Assert(t, len(bkt.Objects()[path.Join(b1.String(), IndexFilename)]) > 0)
testutil.Assert(t, len(bkt.Objects()[path.Join(b1.String(), MetaFilename)]) > 0)
testutil.Assert(t, len(bkt.Objects()[path.Join(DebugMetas, fmt.Sprintf("%s.json", b1.String()))]) == 0)
// If upload of meta.json fails, all uploaded chunks and index are cleaned up.
// This prevents partial blocks from being discovered and eventually deleted by BestEffortCleanAbortedPartialUploads.
testutil.Equals(t, 0, len(bkt.Objects()))
}
}

Expand Down
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