dotnet monitor–Run as a sidecar in a Kubernetes cluster

Baca Juga

Yesterday I blogged about ‘dotnet monitor’ and how it can help you to collect diagnostic artifacts at runtime in a uniform way.

Let’s have a look today on how to use ‘dotnet monitor’ inside a Kubernetes cluster.

When running in a cluster, it is recommend to run the dotnet-monitor container as a sidecar alongside your application container in the same pod.

Here is an example manifest on how to set this up:

	apiVersion: apps/v1
	kind: Deployment
	metadata:
	name: dotnet-monitor-example
	spec:
	replicas: 1
	selector:
	matchLabels:
	app: dotnet-monitor-example
	template:
	metadata:
	labels:
	app: dotnet-monitor-example
	spec:
	volumes:
	- name: diagnostics
	emptyDir: {}
	containers:
	- name: server
	image: mcr.microsoft.com/dotnet/core/samples:aspnetapp
	ports:
	- containerPort: 80
	volumeMounts:
	- mountPath: /tmp
	name: diagnostics
	- name: sidecar
	image: mcr.microsoft.com/dotnet/monitor:5.0.0-preview.5
	ports:
	- containerPort: 52323
	#args: ["--urls", "http://*:52323", "--metricUrls", "http://*:52325"]
	volumeMounts:
	- name: diagnostics
	mountPath: /tmp

view raw dotnetmonitor.yaml hosted with ❤ by GitHub

Most important to notice in the manifest is that you need to share a volume between the application container and the sidecar.

Let’s deploy this manifest:

$ kubectl apply –f ./dotnetmonitor.yaml

Once your pods are up and running, we need to use port forwarding to be able to access the diagnostics endpoint from our local machine.

To do this, we first need to find the name of the pod :

$ kubectl get pod -l app=dotnet-monitor-example
NAME                                 READY   STATUS    RESTARTS   AGE
dotnet-monitor-example-78997f8fdf-nrhp7   2/2     Running   0          5m

Now we know the pod name, we an forward traffic using the kubectl port-forward command:

$ kubectl port-forward pods/dotnet-monitor-example-78997f8fdf-nrhp7 52323:52323

Now we can invoke the different endpoints the same way as before:

$ curl -s http://localhost:52323/processes | jq

Remark: Although the example above worked on my local cluster, I got into trouble when I tried to do use the same steps on AKS. I'll share another post to explain where I got into trouble and how I fixed it.