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feat: return ReasonFailed from ingest-limits frontend #18123

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Merged
merged 1 commit into from
Jun 17, 2025
Merged

feat: return ReasonFailed from ingest-limits frontend #18123

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54 changes: 49 additions & 5 deletions pkg/limits/frontend/frontend.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,9 @@ import (
"github.com/grafana/dskit/ring"
"github.com/grafana/dskit/services"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"

"github.com/grafana/loki/v3/pkg/limits"
limits_client "github.com/grafana/loki/v3/pkg/limits/client"
"github.com/grafana/loki/v3/pkg/limits/proto"
)
Expand All @@ -32,6 +34,11 @@ type Frontend struct {
subservicesWatcher *services.FailureWatcher
lifecycler *ring.Lifecycler
lifecyclerWatcher *services.FailureWatcher

// Metrics.
streams prometheus.Counter
streamsFailed prometheus.Counter
streamsRejected prometheus.Counter
}

// New returns a new Frontend.
Expand Down Expand Up @@ -62,6 +69,24 @@ func New(cfg Config, ringName string, limitsRing ring.ReadRing, logger log.Logge
logger: logger,
gatherer: gatherer,
assignedPartitionsCache: assignedPartitionsCache,
streams: promauto.With(reg).NewCounter(
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Contributor Author

@grobinson-grafana grobinson-grafana Jun 17, 2025

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Thanks to this I was able to move the metrics out of ring.go and into frontend.go.

prometheus.CounterOpts{
Name: "loki_ingest_limits_frontend_streams_total",
Help: "The total number of received streams.",
},
),
streamsFailed: promauto.With(reg).NewCounter(
prometheus.CounterOpts{
Name: "loki_ingest_limits_frontend_streams_failed_total",
Help: "The total number of received streams that could not be checked.",
},
),
streamsRejected: promauto.With(reg).NewCounter(
prometheus.CounterOpts{
Name: "loki_ingest_limits_frontend_streams_rejected_total",
Help: "The total number of rejected streams.",
},
),
}

lifecycler, err := ring.NewLifecycler(cfg.LifecyclerConfig, f, RingName, RingKey, true, logger, reg)
Expand Down Expand Up @@ -89,13 +114,32 @@ func New(cfg Config, ringName string, limitsRing ring.ReadRing, logger log.Logge

// ExceedsLimits implements proto.IngestLimitsFrontendClient.
func (f *Frontend) ExceedsLimits(ctx context.Context, req *proto.ExceedsLimitsRequest) (*proto.ExceedsLimitsResponse, error) {
f.streams.Add(float64(len(req.Streams)))
results := make([]*proto.ExceedsLimitsResult, 0, len(req.Streams))
resps, err := f.gatherer.ExceedsLimits(ctx, req)
if err != nil {
return nil, err
}
results := make([]*proto.ExceedsLimitsResult, 0, len(req.Streams))
for _, resp := range resps {
results = append(results, resp.Results...)
// If the entire call failed, then all streams failed.
for _, stream := range req.Streams {
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@grobinson-grafana grobinson-grafana Jun 17, 2025

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This is implemented as per https://github.com/grafana/deployment_tools/blob/master/docs/loki/limits.md#apis.

results = append(results, &proto.ExceedsLimitsResult{
StreamHash: stream.StreamHash,
Reason: uint32(limits.ReasonFailed),
})
}
f.streamsFailed.Add(float64(len(req.Streams)))
level.Error(f.logger).Log("msg", "failed to check request against limits", "err", err)
} else {
for _, resp := range resps {
for _, res := range resp.Results {
// Even if the call succeeded, some (or all) streams might
// still have failed.
if res.Reason == uint32(limits.ReasonFailed) {
f.streamsFailed.Inc()
} else {
f.streamsRejected.Inc()
}
}
results = append(results, resp.Results...)
}
}
return &proto.ExceedsLimitsResponse{Results: results}, nil
}
Expand Down
49 changes: 44 additions & 5 deletions pkg/limits/frontend/frontend_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,14 @@ package frontend

import (
"context"
"errors"
"testing"
"time"

"github.com/go-kit/log"
"github.com/grafana/dskit/kv"
"github.com/grafana/dskit/ring"
"github.com/prometheus/client_golang/prometheus"
"github.com/stretchr/testify/require"

"github.com/grafana/loki/v3/pkg/limits"
Expand All @@ -16,6 +21,7 @@ func TestFrontend_ExceedsLimits(t *testing.T) {
name string
exceedsLimitsRequest *proto.ExceedsLimitsRequest
exceedsLimitsResponses []*proto.ExceedsLimitsResponse
err error
expected *proto.ExceedsLimitsResponse
}{{
name: "no streams",
Expand Down Expand Up @@ -124,16 +130,49 @@ func TestFrontend_ExceedsLimits(t *testing.T) {
Reason: uint32(limits.ReasonMaxStreams),
}},
},
}, {
name: "unexpected error, response with failed reason",
exceedsLimitsRequest: &proto.ExceedsLimitsRequest{
Tenant: "test",
Streams: []*proto.StreamMetadata{{
StreamHash: 0x1,
TotalSize: 0x5,
}, {
StreamHash: 0x2,
TotalSize: 0x9,
}},
},
err: errors.New("an unexpected error occurred"),
expected: &proto.ExceedsLimitsResponse{
Results: []*proto.ExceedsLimitsResult{{
StreamHash: 0x1,
Reason: uint32(limits.ReasonFailed),
}, {
StreamHash: 0x2,
Reason: uint32(limits.ReasonFailed),
}},
},
}}

for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
f := Frontend{
gatherer: &mockExceedsLimitsGatherer{
t: t,
expectedExceedsLimitsRequest: test.exceedsLimitsRequest,
exceedsLimitsResponses: test.exceedsLimitsResponses,
readRing, _ := newMockRingWithClientPool(t, "test", nil, nil)
f, err := New(Config{
LifecyclerConfig: ring.LifecyclerConfig{
RingConfig: ring.Config{
KVStore: kv.Config{
Store: "inmemory",
},
},
},
}, "test", readRing, log.NewNopLogger(), prometheus.NewRegistry())
require.NoError(t, err)
// Replace with our mock.
f.gatherer = &mockExceedsLimitsGatherer{
t: t,
expectedExceedsLimitsRequest: test.exceedsLimitsRequest,
exceedsLimitsResponses: test.exceedsLimitsResponses,
err: test.err,
}
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
Expand Down
25 changes: 19 additions & 6 deletions pkg/limits/frontend/http_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,10 @@ import (
"net/http/httptest"
"testing"

"github.com/go-kit/log"
"github.com/grafana/dskit/kv"
"github.com/grafana/dskit/ring"
"github.com/prometheus/client_golang/prometheus"
"github.com/stretchr/testify/require"

"github.com/grafana/loki/v3/pkg/limits"
Expand Down Expand Up @@ -71,14 +75,23 @@ func TestFrontend_ServeHTTP(t *testing.T) {

for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
f := Frontend{
gatherer: &mockExceedsLimitsGatherer{
t: t,
expectedExceedsLimitsRequest: test.expectedExceedsLimitsRequest,
exceedsLimitsResponses: test.exceedsLimitsResponses,
readRing, _ := newMockRingWithClientPool(t, "test", nil, nil)
f, err := New(Config{
LifecyclerConfig: ring.LifecyclerConfig{
RingConfig: ring.Config{
KVStore: kv.Config{
Store: "inmemory",
},
},
},
}, "test", readRing, log.NewNopLogger(), prometheus.NewRegistry())
require.NoError(t, err)
f.gatherer = &mockExceedsLimitsGatherer{
t: t,
expectedExceedsLimitsRequest: test.expectedExceedsLimitsRequest,
exceedsLimitsResponses: test.exceedsLimitsResponses,
}
ts := httptest.NewServer(&f)
ts := httptest.NewServer(f)
defer ts.Close()

b, err := json.Marshal(test.request)
Expand Down
9 changes: 5 additions & 4 deletions pkg/limits/frontend/mock_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -24,13 +24,14 @@ type mockExceedsLimitsGatherer struct {

expectedExceedsLimitsRequest *proto.ExceedsLimitsRequest
exceedsLimitsResponses []*proto.ExceedsLimitsResponse
err error
}

func (g *mockExceedsLimitsGatherer) ExceedsLimits(_ context.Context, req *proto.ExceedsLimitsRequest) ([]*proto.ExceedsLimitsResponse, error) {
if expected := g.expectedExceedsLimitsRequest; expected != nil {
require.Equal(g.t, expected, req)
func (m *mockExceedsLimitsGatherer) ExceedsLimits(_ context.Context, req *proto.ExceedsLimitsRequest) ([]*proto.ExceedsLimitsResponse, error) {
if expected := m.expectedExceedsLimitsRequest; expected != nil {
require.Equal(m.t, expected, req)
}
return g.exceedsLimitsResponses, nil
return m.exceedsLimitsResponses, m.err
}

// mockIngestLimitsClient mocks proto.IngestLimitsClient.
Expand Down
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