Prometheus Client Examples

A small collection of examples to demonstrate how to instrument applications with prometheus metrics

Prerequisites

• minikube: tested with v1.8.2
• docker: tested with version 19.03.5

Running

Run a local prometheus monitoring stack on minikube

1. start a fresh version of minikube

   $ minikube delete && minikube start --kubernetes-version=v1.17.3 --memory=6g --bootstrapper=kubeadm --extra-config=kubelet.authentication-token-webhook=true --extra-config=kubelet.authorization-mode=Webhook --extra-config=scheduler.address=0.0.0.0 --extra-config=controller-manager.address=0.0.0.0
   

   The kube-prometheus stack includes a resource metrics API server, so the metrics-server addon is not necessary. Ensure the metrics-server addon is disabled on minikube:

   $ minikube addons disable metrics-server
   $ minikube addons enable ingress
   $ minikube addons enable registry
   

2. Create the monitoring stack using the config in the manifests directory. Create the namespace and CRDs, and then wait for them to be availble before creating the remaining resources

   $ kubectl create -f kube-prometheus/manifests/setup
   $ until kubectl get servicemonitors --all-namespaces ; do date; sleep 1; echo ""; done
   $ kubectl create -f kube-prometheus/manifests/
   $ kubectl create -f client_manifests/
   

3. Build and push all docker images for prometheus client examples make all

4. Add the IP of the minikube ingress into /etc/hosts, along with local DNS names. In this example the minikube ingress IP is 192.168.64.2.

   $ minikube ip
   192.168.64.2
   

   /etc/hosts

   192.168.64.2 alertmanager.internal grafana.internal prometheus.internal ruby-client.internal golang-client.internal python-client.internal
   

5. Review your infrastructure in the browser. Note the default login for grafana is admin/admin

   $ open http://grafana.internal http://alertmanager.internal http://prometheus.internal
   

   

6. Configure the minikube registry as an insecure docker registry, by adding the minikube registry IP:PORT to daemon.json. If you use Docker Desktop for Mac or Docker Desktop for Windows, click the Docker icon, choose Preferences, and choose Docker Engine.

   

   At this point kubernetes is configured with full monitoring stack. We can now deploy our instrumented applications to the cluster.

7. Apply the Deployment, Service, ServiceMonitor, and Ingress for our prometheus clients

   $ kubectl apply -f client-manifests/
   

8. Navigate to all client /metrics endpoints

   $ open http://ruby-client.internal/metrics http://golang-client.internal/metrics http://python-client.internal/metrics
   

Teardown

$ kubectl delete --ignore-not-found=true -f kube-prometheus/manifests/ -f kube-prometheus/manifests/setup -f client_manifests/
$ minikube delete

Troubleshooting

Occsionally the kube-apiserver gets in a bad state in minikube, with the following error.

error: unable to upgrade connection: Authorization error (user=kube-apiserver-kubelet-client, verb=create, resource=nodes, subresource=proxy)

Restarting minikube may help return the apiserver to a working state

$ minikube stop
$ minikube start

References

• client_golang
• client_python
• client_ruby
• kube-prometheus