/
metrics.go
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/
metrics.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package kafka
import (
"context"
"errors"
"fmt"
"strings"
"time"
"github.com/twmb/franz-go/pkg/kgo"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/metric"
semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
)
const (
instrumentName = "github.com/elastic/apm-queue/kafka"
unitCount = "1"
msgProducedCountKey = "producer.messages.count"
msgFetchedKey = "consumer.messages.fetched"
msgDelayKey = "consumer.messages.delay"
errorReasonKey = "error_reason"
)
var (
_ kgo.HookProduceBatchWritten = new(metricHooks)
_ kgo.HookFetchBatchRead = new(metricHooks)
_ kgo.HookFetchRecordUnbuffered = new(metricHooks)
_ kgo.HookProduceRecordUnbuffered = new(metricHooks)
)
// TopicAttributeFunc run on `kgo.HookProduceBatchWritten` and
// `kgo.HookFetchBatchRead` for each topic/partition. It can be
// used include additionaly dimensions for `consumer.messages.fetched`
// and `producer.messages.count` metrics.
type TopicAttributeFunc func(topic string) attribute.KeyValue
type metricHooks struct {
namespace string
topicPrefix string
messageProduced metric.Int64Counter
messageFetched metric.Int64Counter
messageDelay metric.Float64Histogram
topicAttributeFunc TopicAttributeFunc
}
func newKgoHooks(mp metric.MeterProvider, namespace, topicPrefix string,
topicAttributeFunc TopicAttributeFunc,
) (*metricHooks, error) {
m := mp.Meter(instrumentName)
messageProducedCounter, err := m.Int64Counter(msgProducedCountKey,
metric.WithDescription("The number of messages produced"),
metric.WithUnit(unitCount),
)
if err != nil {
return nil, formatMetricError(msgProducedCountKey, err)
}
messageFetchedCounter, err := m.Int64Counter(msgFetchedKey,
metric.WithDescription("The number of messages that were fetched from a kafka topic"),
metric.WithUnit(unitCount),
)
if err != nil {
return nil, formatMetricError(msgFetchedKey, err)
}
messageDelayHistogram, err := m.Float64Histogram(msgDelayKey,
metric.WithDescription("The delay between producing messages and reading them"),
metric.WithUnit("s"),
)
if err != nil {
return nil, formatMetricError(msgDelayKey, err)
}
if topicAttributeFunc == nil {
topicAttributeFunc = func(topic string) attribute.KeyValue {
return attribute.KeyValue{}
}
}
return &metricHooks{
namespace: namespace,
topicPrefix: topicPrefix,
// Producer
messageProduced: messageProducedCounter,
// Consumer
messageFetched: messageFetchedCounter,
messageDelay: messageDelayHistogram,
topicAttributeFunc: topicAttributeFunc,
}, nil
}
func formatMetricError(name string, err error) error {
return fmt.Errorf("cannot create %s metric: %w", name, err)
}
// HookProduceBatchWritten is called when a batch has been produced.
func (h *metricHooks) OnProduceBatchWritten(_ kgo.BrokerMetadata,
topic string, partition int32, m kgo.ProduceBatchMetrics,
) {
attrs := make([]attribute.KeyValue, 0, 6)
attrs = append(attrs, semconv.MessagingSystem("kafka"),
semconv.MessagingDestinationName(strings.TrimPrefix(topic, h.topicPrefix)),
semconv.MessagingKafkaDestinationPartition(int(partition)),
attribute.String("outcome", "success"),
)
if kv := h.topicAttributeFunc(topic); kv != (attribute.KeyValue{}) {
attrs = append(attrs, kv)
}
if h.namespace != "" {
attrs = append(attrs, attribute.String("namespace", h.namespace))
}
h.messageProduced.Add(context.Background(), int64(m.NumRecords),
metric.WithAttributeSet(attribute.NewSet(attrs...)),
)
}
// OnFetchBatchRead is called once per batch read from Kafka. Records
// `consumer.messages.fetched`.
func (h *metricHooks) OnFetchBatchRead(_ kgo.BrokerMetadata,
topic string, partition int32, m kgo.FetchBatchMetrics,
) {
attrs := make([]attribute.KeyValue, 0, 5)
attrs = append(attrs, semconv.MessagingSystem("kafka"),
semconv.MessagingSourceName(strings.TrimPrefix(topic, h.topicPrefix)),
semconv.MessagingKafkaSourcePartition(int(partition)),
)
if kv := h.topicAttributeFunc(topic); kv != (attribute.KeyValue{}) {
attrs = append(attrs, kv)
}
if h.namespace != "" {
attrs = append(attrs, attribute.String("namespace", h.namespace))
}
h.messageFetched.Add(context.Background(), int64(m.NumRecords),
metric.WithAttributeSet(attribute.NewSet(attrs...)),
)
}
// OnProduceRecordUnbuffered records the number of produced messages that were
// not produced due to errors. The successfully produced records is recorded by
// `OnProduceBatchWritten`.
// https://pkg.go.dev/github.com/twmb/franz-go/pkg/kgo#HookProduceRecordUnbuffered
func (h *metricHooks) OnProduceRecordUnbuffered(r *kgo.Record, err error) {
if err == nil {
return // Covered by OnProduceBatchWritten.
}
attrs := attributesFromRecord(r,
semconv.MessagingDestinationName(strings.TrimPrefix(r.Topic, h.topicPrefix)),
semconv.MessagingKafkaDestinationPartition(int(r.Partition)),
attribute.String("outcome", "failure"),
)
if h.namespace != "" {
attrs = append(attrs, attribute.String("namespace", h.namespace))
}
if errors.Is(err, context.DeadlineExceeded) {
attrs = append(attrs, attribute.String(errorReasonKey, "timeout"))
} else if errors.Is(err, context.Canceled) {
attrs = append(attrs, attribute.String(errorReasonKey, "canceled"))
} else {
attrs = append(attrs, attribute.String(errorReasonKey, "unknown"))
}
h.messageProduced.Add(context.Background(), 1, metric.WithAttributeSet(
attribute.NewSet(attrs...),
))
}
// OnFetchRecordUnbuffered records the message delay of fetched messages.
// https://pkg.go.dev/github.com/twmb/franz-go/pkg/kgo#HookFetchRecordUnbuffered
func (h *metricHooks) OnFetchRecordUnbuffered(r *kgo.Record, polled bool) {
if !polled {
return // Record metrics when polled by `client.PollRecords()`.
}
attrs := attributesFromRecord(r,
semconv.MessagingSourceName(strings.TrimPrefix(r.Topic, h.topicPrefix)),
semconv.MessagingKafkaSourcePartition(int(r.Partition)),
)
if h.namespace != "" {
attrs = append(attrs, attribute.String("namespace", h.namespace))
}
h.messageDelay.Record(context.Background(),
time.Since(r.Timestamp).Seconds(),
metric.WithAttributeSet(attribute.NewSet(attrs...)),
)
}
func attributesFromRecord(r *kgo.Record, extra ...attribute.KeyValue) []attribute.KeyValue {
attrs := make([]attribute.KeyValue, 0, 5) // Preallocate 5 elements.
attrs = append(attrs, semconv.MessagingSystem("kafka"))
attrs = append(attrs, extra...)
for _, v := range r.Headers {
if v.Key == "traceparent" { // Ignore traceparent.
continue
}
attrs = append(attrs, attribute.String(v.Key, string(v.Value)))
}
return attrs
}