Redis replica offset (open-telemetry#29565)

**Description:** Adds missing metrics for `slave_repl_offset` and adds
an integration test to configure a cluster to test such

**Link to tracking Issue:**
[`6942`](open-telemetry#6942)

**Testing:** `cd receiver/redisreceiver && make mod-integration-test`

**Documentation:** (autogenerated from mdatagen)

.chloggen/redis_replica_offset.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: redisreciever
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: adds metric for slave_repl_offset
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [6942]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: also adds a shell script to set up docker-compose integration test
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/redisreceiver/documentation.md

@@ -329,6 +329,14 @@ The value of the maxmemory configuration directive
 | ---- | ----------- | ---------- |
 | By | Gauge | Int |
 
+### redis.replication.replica_offset
+
+Offset for redis replica
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| By | Gauge | Int |
+
 ### redis.role
 
 Redis node's role

receiver/redisreceiver/integration_test.go

@@ -8,7 +8,9 @@ package redisreceiver
 
 import (
 	"fmt"
+	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/testcontainers/testcontainers-go"
 	"github.com/testcontainers/testcontainers-go/wait"
@@ -20,7 +22,7 @@ import (
 
 const redisPort = "6379"
 
-func TestIntegration(t *testing.T) {
+func TestIntegrationV6(t *testing.T) {
 	scraperinttest.NewIntegrationTest(
 		NewFactory(),
 		scraperinttest.WithContainerRequest(
@@ -46,5 +48,46 @@ func TestIntegration(t *testing.T) {
 				return redisPort
 			}),
 		),
+		scraperinttest.WithExpectedFile(filepath.Join("testdata", "integration", "expected-old.yaml")),
+	).Run(t)
+}
+
+func TestIntegrationV7Cluster(t *testing.T) {
+	scraperinttest.NewIntegrationTest(
+		NewFactory(),
+		scraperinttest.WithContainerRequest(testcontainers.ContainerRequest{
+			ExposedPorts: []string{
+				redisPort,
+				"6380",
+				"6381",
+				"6382",
+				"6383",
+				"6384",
+				"6385",
+			},
+			FromDockerfile: testcontainers.FromDockerfile{
+				Context:    filepath.Join("testdata", "integration"),
+				Dockerfile: "Dockerfile.cluster",
+			},
+			WaitingFor: wait.ForListeningPort("6385").WithStartupTimeout(30 * time.Second),
+		}),
+		scraperinttest.WithCustomConfig(
+			func(t *testing.T, cfg component.Config, ci *scraperinttest.ContainerInfo) {
+				rCfg := cfg.(*Config)
+				// Strictly speaking this is non-deterministic and may not be the right port for one with repl offset
+				// However, we're using socat and some port forwarding in the Dockerfile to ensure this always points
+				// to a replica node, so in practice any failures due to cluster node role changes is unlikely
+				rCfg.Endpoint = fmt.Sprintf("%s:%s", ci.Host(t), ci.MappedPort(t, "6385"))
+				rCfg.MetricsBuilderConfig.Metrics.RedisReplicationReplicaOffset.Enabled = true
+			}),
+		scraperinttest.WithCompareOptions(
+			pmetrictest.IgnoreMetricValues(),
+			pmetrictest.IgnoreMetricDataPointsOrder(),
+			pmetrictest.IgnoreStartTimestamp(),
+			pmetrictest.IgnoreTimestamp(),
+		),
+		scraperinttest.WithExpectedFile(filepath.Join("testdata", "integration", "expected-cluster.yaml")),
+		scraperinttest.WithCreateContainerTimeout(time.Minute),
+		scraperinttest.WithCompareTimeout(time.Minute),
 	).Run(t)
 }

receiver/redisreceiver/internal/metadata/testdata/config.yaml

@@ -63,6 +63,8 @@ all_set:
       enabled: true
     redis.replication.offset:
       enabled: true
+    redis.replication.replica_offset:
+      enabled: true
     redis.role:
       enabled: true
     redis.slaves.connected:
@@ -140,6 +142,8 @@ none_set:
       enabled: false
     redis.replication.offset:
       enabled: false
+    redis.replication.replica_offset:
+      enabled: false
     redis.role:
       enabled: false
     redis.slaves.connected:

receiver/redisreceiver/metadata.yaml

@@ -344,7 +344,13 @@ metrics:
     gauge:
       value_type: int
     attributes: [db]
-
+  # below are all disabled by default
+  redis.replication.replica_offset:
+    enabled: false
+    description: "Offset for redis replica"
+    unit: "By"
+    gauge:
+      value_type: int
 tests:
   config:
     endpoint: localhost:6379

receiver/redisreceiver/metric_functions.go

@@ -30,6 +30,7 @@ func (rs *redisScraper) dataPointRecorders() map[string]any {
 		"rdb_changes_since_last_save":     rs.mb.RecordRedisRdbChangesSinceLastSaveDataPoint,
 		"rejected_connections":            rs.mb.RecordRedisConnectionsRejectedDataPoint,
 		"repl_backlog_first_byte_offset":  rs.mb.RecordRedisReplicationBacklogFirstByteOffsetDataPoint,
+		"slave_repl_offset":               rs.mb.RecordRedisReplicationReplicaOffsetDataPoint,
 		"total_commands_processed":        rs.mb.RecordRedisCommandsProcessedDataPoint,
 		"total_connections_received":      rs.mb.RecordRedisConnectionsReceivedDataPoint,
 		"total_net_input_bytes":           rs.mb.RecordRedisNetInputDataPoint,

receiver/redisreceiver/redis_scraper_test.go

@@ -28,8 +28,8 @@ func TestRedisRunnable(t *testing.T) {
 	md, err := runner.Scrape(context.Background())
 	require.NoError(t, err)
 	// + 6 because there are two keyspace entries each of which has three metrics
-	// -1 because maxmemory is by default disabled, so recorder is there, but there won't be data point
-	assert.Equal(t, len(rs.dataPointRecorders())+6-1, md.DataPointCount())
+	// -2 because maxmemory and slave_repl_offset is by default disabled, so recorder is there, but there won't be data point
+	assert.Equal(t, len(rs.dataPointRecorders())+6-2, md.DataPointCount())
 	rm := md.ResourceMetrics().At(0)
 	ilm := rm.ScopeMetrics().At(0)
 	il := ilm.Scope()

receiver/redisreceiver/testdata/integration/Dockerfile.cluster

@@ -0,0 +1,31 @@
+# Use the official Redis image as the base
+FROM redis:7.2.3
+
+RUN apt update && apt install --assume-yes socat
+
+# Seems to be an upstream issue with testcontainers or scraperint when using named nodes or clusters, so manually do it
+COPY cluster.sh /usr/local/bin/cluster.sh
+COPY configure-nodes.sh /usr/local/bin/configure-nodes.sh
+COPY redis-cluster.conf /etc/redis-cluster.conf
+
+RUN chown redis:redis /usr/local/bin/cluster.sh
+RUN chmod +x /usr/local/bin/cluster.sh
+
+RUN chown redis:redis /usr/local/bin/configure-nodes.sh
+RUN chmod +x /usr/local/bin/configure-nodes.sh
+
+RUN configure-nodes.sh
+RUN chown redis:redis /etc/redis-cluster*.conf
+
+RUN mkdir -p /var/log/redis
+RUN chgrp redis /var/log/redis
+
+EXPOSE 6379
+EXPOSE 6380
+EXPOSE 6381
+EXPOSE 6382
+EXPOSE 6383
+EXPOSE 6384
+EXPOSE 6385
+ENTRYPOINT ["cluster.sh"]
+CMD ["cluster.sh"]

receiver/redisreceiver/testdata/integration/cluster.sh

@@ -0,0 +1,43 @@
+#!/bin/sh -eux
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+
+redis-server /etc/redis-cluster-6379.conf && \
+    redis-server /etc/redis-cluster-6380.conf && \
+    redis-server /etc/redis-cluster-6381.conf && \
+    redis-server /etc/redis-cluster-6382.conf && \
+    redis-server /etc/redis-cluster-6383.conf && \
+    redis-server /etc/redis-cluster-6384.conf
+redis-cli -p 6379 ping
+redis-cli -p 6380 ping
+redis-cli -p 6381 ping
+redis-cli -p 6382 ping
+redis-cli -p 6383 ping
+redis-cli -p 6384 ping
+
+redis-cli --cluster create localhost:6379 localhost:6380 localhost:6381 localhost:6382 localhost:6383 localhost:6384 --cluster-replicas 1 --cluster-yes
+sleep 10s
+while true; do
+    if redis-cli -p 6379 cluster info | grep -q "cluster_state:ok" ; then
+        break
+    fi
+    echo "awaiting for cluster to be ready"
+    sleep 2
+done
+
+
+# ensure a consistent mapping to a replica on port 6385
+REPLICA_PORT=$(redis-cli -p 6379 cluster nodes | grep 'slave' | awk '{print $2}' | cut -d':' -f2 | head -n 1)
+REPLICA_PORT=${REPLICA_PORT%@*}
+if [ -n "$REPLICA_PORT" ]; then
+  echo "forwarding from port $REPLICA_PORT to 6385"
+  #ssh -fNL "6385:127.0.0.1:$REPLICA_PORT" 127.0.0.1
+  nohup socat tcp-listen:6385,fork,reuseaddr,forever,reuseaddr,keepalive,keepidle=10,keepintvl=10,keepcnt=2 tcp-connect:127.0.0.1:"$REPLICA_PORT" &
+else
+  echo "could not find replica port" 1>&2
+  exit 1
+fi
+
+tail -f /dev/null
+#ssh -fNL 6385:localhost:$REPLICA_PORT