Setting up gcloud defaults

To configure gcloud with defaults for your Cloud Run service:

1. Set your default project:

   gcloudconfigsetprojectPROJECT_ID

   ReplacePROJECT_ID with the name of the project you created forthis tutorial.

2. Configure gcloud for your chosen region:

   gcloudconfigsetrun/regionREGION

   ReplaceREGION with the supported Cloud Runregionof your choice.

Creating a Artifact Registry image repository

Create an Artifact Registry Docker repository to host the sample service image:

gcloud artifacts repositories create run-otel \    --repository-format=docker \    --location=REGION \    --project=PROJECT_ID

Replace the following:

• PROJECT_ID with the name of the project you created for this tutorial.
• REGION REGION with the supportedCloud Run region of your choice.

Retrieving the code sample

To retrieve the code sample for use:

1. Clone the sample app repository to your local machine:

   Go

   gitclonehttps://github.com/GoogleCloudPlatform/golang-samples.git

   Alternatively, you can download the sample as a zip file and extract it.

2. Change to the directory that contains the Cloud Run samplecode:

   Go

   cdgolang-samples/run/custom-metrics/

Reviewing the code

The code for this tutorial consists of the following:

• A server that handles incoming requests and generates a metric namedsidecar_sample_counter_total.

packagemainimport("context""fmt""log""net/http""os""go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc""go.opentelemetry.io/otel/metric"sdkmetric"go.opentelemetry.io/otel/sdk/metric""go.opentelemetry.io/otel/sdk/resource"semconv"go.opentelemetry.io/otel/semconv/v1.24.0")varcountermetric.Int64Counterfuncmain(){ctx:=context.Background()shutdown:=setupCounter(ctx)defershutdown(ctx)port:=os.Getenv("PORT")ifport==""{port="8080"log.Printf("defaulting to port %s",port)}http.HandleFunc("/",handler)log.Fatal(http.ListenAndServe(":"+port,nil))}funchandler(whttp.ResponseWriter,r*http.Request){counter.Add(context.Background(),100)fmt.Fprintln(w,"Incremented sidecar_sample_counter_total metric!")}funcsetupCounter(ctxcontext.Context)func(context.Context)error{serviceName:=os.Getenv("K_SERVICE")ifserviceName==""{serviceName="sample-cloud-run-app"}r,err:=resource.Merge(resource.Default(),resource.NewWithAttributes(resource.Default().SchemaURL(),semconv.ServiceName(serviceName),),)iferr!=nil{log.Fatalf("Error creating resource: %v",err)}exporter,err:=otlpmetricgrpc.New(ctx,otlpmetricgrpc.WithInsecure(),)iferr!=nil{log.Fatalf("Error creating exporter: %s",err)}provider:=sdkmetric.NewMeterProvider(sdkmetric.WithReader(sdkmetric.NewPeriodicReader(exporter)),sdkmetric.WithResource(r),)meter:=provider.Meter("example.com/metrics")counter,err=meter.Int64Counter("sidecar-sample-counter")iferr!=nil{log.Fatalf("Error creating counter: %s",err)}returnprovider.Shutdown}

• ADockerfile that defines the operating environment for the service.

FROMgolang:1.24asbuilderWORKDIR/appCOPY..RUNCGO_ENABLED=0GOOS=linuxgobuild-osample-appFROMalpine:3RUNapkadd--no-cacheca-certificatesCOPY--from=builder/app/sample-app/sample-appCMD["/sample-app"]

The sample also includes files under thecollector subdirectory for building a custom collector:

• A config file for the collector.

  receivers:otlp:protocols:grpc:http:processors:batch:#batchmetricsbeforesendingtoreduceAPIusagesend_batch_max_size:200send_batch_size:200timeout:5smemory_limiter:#dropmetricsifmemoryusagegetstoohighcheck_interval:1slimit_percentage:65spike_limit_percentage:20#automaticallydetectCloudRunresourcemetadataresourcedetection:detectors:[env,gcp]timeout:2soverride:falseresource:attributes:#addinstance_idasaresourceattribute-key:service.instance.idfrom_attribute:faas.idaction:upsert#parseservicenamefromK_SERVICECloudRunvariable-key:service.namevalue:${env:K_SERVICE}action:insertexporters:googlemanagedprometheus:#Note:thisisintentionallyleftblankextensions:health_check:endpoint:0.0.0.0:13133service:extensions:[health_check]pipelines:metrics:receivers:[otlp]processors:[batch,memory_limiter,resourcedetection,resource]exporters:[googlemanagedprometheus]

• ADockerfile that bundles the provided config into an upstream Collectorimage.

  FROMus-docker.pkg.dev/cloud-ops-agents-artifacts/google-cloud-opentelemetry-collector/otelcol-google:0.121.0COPYcollector-config.yaml/etc/otelcol-google/config.yaml

Shipping the code

Shipping code consists of three steps: building a container image withCloud Build, uploading the container image to Artifact Registry, anddeploying the container image to Cloud Run.

To ship your code:

1. Build your sample service container and publish on Artifact Registry:

   gcloudbuildssubmit--tagREGION-docker.pkg.dev/PROJECT_ID/run-otel/sample-metrics-app

   Upon success, you should see a SUCCESS message containing the ID, creation time, and image name. The image is stored in Artifact Registry and can be re-used if desired.

2. Build your Collector container and publish on Artifact Registry:

   gcloudbuildssubmitcollector--tagREGION-docker.pkg.dev/PROJECT_ID/run-otel/otel-collector-metrics

   Upon success, you should see a SUCCESS message containing the ID, creation time, and image name. The image is stored in Artifact Registry and can be re-used if desired.

3. Deploy your application:

   YAML

   1. Create a new file calledservice.yaml with the following:

      apiVersion: serving.knative.dev/v1kind: Servicemetadata:  name:SERVICE-NAME  annotations:    run.googleapis.com/launch-stage: BETAspec:  template:    metadata:      annotations:        run.googleapis.com/container-dependencies: "{app:[collector]}"    spec:      containers:      - image:REGION-docker.pkg.dev/PROJECT_ID/run-otel/sample-metrics-app        name: app        ports:        - containerPort:CONTAINER_PORT        env:        - name: "OTEL_EXPORTER_OTLP_ENDPOINT"          value: "http://localhost:4317"      - image:REGION-docker.pkg.dev/PROJECT_ID/run-otel/otel-collector-metrics        name: collector        startupProbe:          httpGet:            path: /            port: 13133

   2. Replace the following:
      • CONTAINER_PORT with theport your service's ingress container listens on. By default, this is8080.
      • SERVICE-NAME with any name for your service, such ascustom-metrics-sample-service.

4. Create the new service with the following command:

   gcloud run services replace service.yaml

   This command returns a service URL. Use this URL to try out the sample application inTrying it out.

Trying it out

Using the URL from thegcloud run command inShipping the code,connect to the service to generate some sample metrics (you can run thiscommand several times to generate more interesting data):

curl -H \"Authorization: Bearer $(gcloud auth print-identity-token)" \SERVICE_URL

ReplaceSERVICE_URL with the URL of your service.

Next, navigate to theMetrics Explorerwithin the Cloud Monitoring section of the Google Cloud console and select thesidecar_sample_counter_total metric.

You can also query the metrics withPromQL. For example, the query below will filter metrics based on the Cloud Run instance ID:

sidecar_sample_counter_total{instance="INSTANCE_ID"}

ReplaceINSTANCE_ID with the ID of any instance for your service (available in the instance logs or from themetadata server).

This query produces a chart like the one below: