Observability: Monitoring, logging, and tracing sample - Go

This sample runs a simple web server that makes calls to other in-cluster services and responds to requests with “Hello World!”. The purpose of this sample is to show generating metrics, logs and distributed traces. This sample also shows how to create a dedicated Prometheus instance rather than using the default installation.

Prerequisites

1. A Kubernetes cluster with Knative Serving installed and DNS configured.
2. Check if Knative monitoring components are installed:

kubectl get pods --namespace knative-monitoring

• If pods aren’t found, install Knative monitoring component.

1. Install Docker.
2. Check out the code:

go get -d github.com/knative/docs/docs/serving/samples/telemetry-go

Setup

Build the application container and publish it to a container registry:

1. Move into the sample directory:

cd $GOPATH/src/github.com/knative/docs

1. Set your preferred container registry:

export REPO="gcr.io/<YOUR_PROJECT_ID>"

This example shows how to use Google Container Registry (GCR). You will need a Google Cloud Project and to enable the Google Container Registry API.

1. Use Docker to build your application container:

docker build \
  --tag "${REPO}/docs/serving/samples/telemetry-go" \
  --file=docs/serving/samples/telemetry-go/Dockerfile .

1. Push your container to a container registry:

docker push "${REPO}/docs/serving/samples/telemetry-go"

1. Replace the image reference path with our published image path in the configuration file (docs/serving/samples/telemetry-go/sample.yaml):

   • Manually replace: image: github.com/knative/docs/docs/serving/samples/telemetry-go with image: <YOUR_CONTAINER_REGISTRY>/docs/serving/samples/telemetry-go

     Or

   • Use run this command:

     perl -pi -e "s@github.com/knative/docs@${REPO}@g" docs/serving/samples/telemetry-go/sample.yaml

Deploy the Service

Deploy this application to Knative Serving:

kubectl apply --filename docs/serving/samples/telemetry-go/

Explore the Service

Inspect the created resources with the kubectl commands:

• View the created Route resource:

kubectl get route --output yaml

• View the created Configuration resource:

kubectl get configurations --output yaml

• View the Revision that was created by the Configuration:

kubectl get revisions --output yaml

Access the Service

To access this service via curl, you need to determine its ingress address.

1. To determine if your route is ready:

kubectl get route

When the route is ready, you’ll see the following fields reported as:

telemetrysample-route   http://telemetrysample-route.default.example.com   True

1. Make a request to the service to see the Hello World! message:

curl http://telemetrysample-route.default.example.com

1. Make a request to the /log endpoint to generate logs to the stdout file and generate files under /var/log in both JSON and plain text formats:

curl http://telemetrysample-route.default.example.com/log

Access Logs

You can access to the logs from Kibana UI - see Logs for more information.

Access per Request Traces

You can access to per request traces from Zipkin UI - see Traces for more information.

Accessing Custom Metrics

You can see published metrics using Prometheus UI. To access to the UI, forward the Prometheus server to your machine:

kubectl port-forward $(kubectl get pods --selector=app=prometheus-test --output=jsonpath="{.items[0].metadata.name}") 9090

Then browse to http://localhost:9090.

Clean up

To clean up the sample service:

kubectl delete --filename docs/serving/samples/telemetry-go/