Add opentelemetry tracing for Redis (#7598)

This pulls in the redisotel "extra" from the go-redis driver and
instruments our Redis connections with it.

go.mod

@@ -24,7 +24,8 @@ require (
 	github.com/nxadm/tail v1.4.11
 	github.com/prometheus/client_golang v1.15.1
 	github.com/prometheus/client_model v0.4.0
-	github.com/redis/go-redis/v9 v9.4.0
+	github.com/redis/go-redis/extra/redisotel/v9 v9.5.3
+	github.com/redis/go-redis/v9 v9.5.3
 	github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399
 	github.com/weppos/publicsuffix-go v0.30.3-0.20240510084413-5f1d03393b3d
 	github.com/zmap/zcrypto v0.0.0-20231219022726-a1f61fb1661c
@@ -78,6 +79,7 @@ require (
 	github.com/poy/onpar v1.1.2 // indirect
 	github.com/prometheus/common v0.42.0 // indirect
 	github.com/prometheus/procfs v0.9.0 // indirect
+	github.com/redis/go-redis/extra/rediscmd/v9 v9.5.3 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.27.0 // indirect
 	go.opentelemetry.io/otel/metric v1.27.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.2.0 // indirect

go.sum

@@ -214,8 +214,12 @@ github.com/prometheus/procfs v0.0.0-20190507164030-5867b95ac084/go.mod h1:TjEm7z
 github.com/prometheus/procfs v0.9.0 h1:wzCHvIvM5SxWqYvwgVL7yJY8Lz3PKn49KQtpgMYJfhI=
 github.com/prometheus/procfs v0.9.0/go.mod h1:+pB4zwohETzFnmlpe6yd2lSc+0/46IYZRB/chUwxUZY=
 github.com/prometheus/tsdb v0.7.1/go.mod h1:qhTCs0VvXwvX/y3TZrWD7rabWM+ijKTux40TwIPHuXU=
-github.com/redis/go-redis/v9 v9.4.0 h1:Yzoz33UZw9I/mFhx4MNrB6Fk+XHO1VukNcCa1+lwyKk=
-github.com/redis/go-redis/v9 v9.4.0/go.mod h1:hdY0cQFCN4fnSYT6TkisLufl/4W5UIXyv0b/CLO2V2M=
+github.com/redis/go-redis/extra/rediscmd/v9 v9.5.3 h1:1/BDligzCa40GTllkDnY3Y5DTHuKCONbB2JcRyIfl20=
+github.com/redis/go-redis/extra/rediscmd/v9 v9.5.3/go.mod h1:3dZmcLn3Qw6FLlWASn1g4y+YO9ycEFUOM+bhBmzLVKQ=
+github.com/redis/go-redis/extra/redisotel/v9 v9.5.3 h1:kuvuJL/+MZIEdvtb/kTBRiRgYaOmx1l+lYJyVdrRUOs=
+github.com/redis/go-redis/extra/redisotel/v9 v9.5.3/go.mod h1:7f/FMrf5RRRVHXgfk7CzSVzXHiWeuOQUu2bsVqWoa+g=
+github.com/redis/go-redis/v9 v9.5.3 h1:fOAp1/uJG+ZtcITgZOfYFmTKPE7n4Vclj1wZFgRciUU=
+github.com/redis/go-redis/v9 v9.5.3/go.mod h1:hdY0cQFCN4fnSYT6TkisLufl/4W5UIXyv0b/CLO2V2M=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
 github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=

redis/config.go

@@ -3,11 +3,13 @@ package redis
 import (
 	"fmt"
 
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/redis/go-redis/extra/redisotel/v9"
+	"github.com/redis/go-redis/v9"
+
 	"github.com/letsencrypt/boulder/cmd"
 	"github.com/letsencrypt/boulder/config"
 	blog "github.com/letsencrypt/boulder/log"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/redis/go-redis/v9"
 )
 
 // Config contains the configuration needed to act as a Redis client.
@@ -163,6 +165,11 @@ func NewRingFromConfig(c Config, stats prometheus.Registerer, log blog.Logger) (
 		lookup.start()
 	}
 
+	err = redisotel.InstrumentTracing(inner)
+	if err != nil {
+		return nil, err
+	}
+
 	return &Ring{
 		Ring:   inner,
 		lookup: lookup,