Linkerd

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Learning Resources

Example Notes

If you want to get started with Linkerd, for the most part, just follow their Documentation. :)

In some of the previous videos, we looked as Service Mesh, and specifically at Istio. Since many people struggle to set-up Istio I thought it would be great to take another look at a different Service Mesh. In this case, at Linkerd.

Note that Istio is still one of the most popular. Thus, it is always good to still know about that but as an alternative, let's also take a look at Linkerd.

Benefits of Linkerd

It works as it is — Saiyam

  • First service mesh project that introduced the term
  • In production for about 4 years
  • Open governance model and hosted by the CNCF
  • Super extensible and easy to install add-ons
  • Easy to install
  • It is a community project
  • Kept small, you should spend the least amount of resources

More information

Control plane written in Go and data plane written in Rust.

Installation

LinkerD has a really neat getting-started documentation that you can follow step-by-step.

First, we are going to follow the onboarding documentation. Once we have everything set-up and working, we want to see metrics of our application through Prometheus and Grafana.

Usually I would copy paste commands to make sure everyone knows the order but since their documentation is pretty straight-forward, I am not going to do that this time.

  1. Let's follow the steps detailed in the getting-started documentation https://linkerd.io/2.10/getting-started/

In our case, we are going to try it out on our Docker for Desktop Kubernetes cluster but you could also use another cluster such as KinD.

Small side-note, I absolutely love that they have a checker command to see whether LinkerD can actually be installed on your cluster

linkerd check --pre

How amazing is that?

And then, they have a separate command to see whether all the resources are ready

linkerd check

I am already in love with them!

We are going to keep following the guide, because we want to have a fancy dashboard with metrics in the end

linkerd viz install | kubectl apply -f -

linkerd jaeger install | kubectl apply -f -

Then we are going to check that everything is ready

linkerd check

Access the dashboard

**linkerd viz dashboard &**

this will give you the localhost port to a beautiful Dashboard

We are going to use the following GitHub respository to install our application

https://github.com/AnaisUrlichs/react-article-display

After clone, cd into react-article-display

Now you want to have Helm istalled since this application relies on a Helm Chart

helm install react-article ./charts/example-chart

Once installed, we can port-forward to access our application

kubectl por-forward service/react-article-example-chart 5000:80

Now we just have to connect our Service Mesh with the application

kubectl get deploy -o yaml \
  | linkerd inject - \
  | kubectl apply -f -

Then we can go ahead and run checks again

linkerd check --proxy

We can see the live stats of our application through

linkerd viz stat deploy

And see the stream of requests to our services throug

linkerd viz tap deploy/web

Now let's go ahead and see how we can do traffic splitting for Canary deployments with Linkerd. For this, we are going to follow the documentation https://linkerd.io/2.10/tasks/canary-release/

Clone the following repository

Apply the first application

kubectl apply -f app-one.yaml

You can access it through kubectl port forwarding

kubectl port-forward service/app-one 3000:80

Install Flagger

kubectl apply -k github.com/fluxcd/flagger/kustomize/linkerd

Deploy the deployment resource

kubectl create ns test && \
  kubectl apply -f https://run.linkerd.io/flagger.yml

Ensure they are ready

kubectl -n test rollout status deploy podinfo

Access the service

kubectl -n test port-forward svc/podinfo 9898

kubectl -n test get ev --watch