# Introduction to Linkerd ## We need a Kubernetes cluster Lets create a Kubernetes cluster to play with using [kind](https://kind.sigs.k8s.io/docs/user/quick-start/) ``` kind create cluster --name linkerd --image kindest/node:v1.19.1 ``` ## Deploy our microservices (Video catalog) ``` # ingress controller kubectl create ns ingress-nginx kubectl apply -f kubernetes/servicemesh/applications/ingress-nginx/ # applications kubectl apply -f kubernetes/servicemesh/applications/playlists-api/ kubectl apply -f kubernetes/servicemesh/applications/playlists-db/ kubectl apply -f kubernetes/servicemesh/applications/videos-web/ kubectl apply -f kubernetes/servicemesh/applications/videos-api/ kubectl apply -f kubernetes/servicemesh/applications/videos-db/ ``` ## Make sure our applications are running ``` kubectl get pods NAME READY STATUS RESTARTS AGE playlists-api-d7f64c9c6-rfhdg 1/1 Running 0 2m19s playlists-db-67d75dc7f4-p8wk5 1/1 Running 0 2m19s videos-api-7769dfc56b-fsqsr 1/1 Running 0 2m18s videos-db-74576d7c7d-5ljdh 1/1 Running 0 2m18s videos-web-598c76f8f-chhgm 1/1 Running 0 100s ``` ## Make sure our ingress controller is running ``` kubectl -n ingress-nginx get pods NAME READY STATUS RESTARTS AGE nginx-ingress-controller-6fbb446cff-8fwxz 1/1 Running 0 2m38s nginx-ingress-controller-6fbb446cff-zbw7x 1/1 Running 0 2m38s ``` We'll need a fake DNS name `servicemesh.demo`
Let's fake one by adding the following entry in our hosts (`C:\Windows\System32\drivers\etc\hosts`) file:
``` 127.0.0.1 servicemesh.demo ``` ## Let's access our applications via Ingress ``` kubectl -n ingress-nginx port-forward deploy/nginx-ingress-controller 80 ``` ## Access our application in the browser We should be able to access our site under `http://servicemesh.demo/home/`
# Getting Started with Linkerd Firstly, I like to do most of my work in containers so everything is reproducible
and my machine remains clean. ## Get a container to work in
Run a small `alpine linux` container where we can install and play with `linkerd`:
``` docker run -it --rm -v ${HOME}:/root/ -v ${PWD}:/work -w /work --net host alpine sh # install curl & kubectl apk add --no-cache curl nano curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl chmod +x ./kubectl mv ./kubectl /usr/local/bin/kubectl export KUBE_EDITOR="nano" #test cluster access: /work # kubectl get nodes NAME STATUS ROLES AGE VERSION linkerd-control-plane Ready master 26m v1.19.1 ``` ## Linkerd CLI Lets download the `linkerd` command line tool
I grabbed the `edge-20.10.1` release using `curl` You can go to the [releases](https://github.com/linkerd/linkerd2/releases/tag/edge-20.10.1) page to get it ``` curl -L -o linkerd https://github.com/linkerd/linkerd2/releases/download/edge-20.10.1/linkerd2-cli-edge-20.10.1-linux-amd64 chmod +x linkerd && mv ./linkerd /usr/local/bin/ linkerd --help ``` ## Pre flight checks Linkerd has a great capability to check compatibility with the target cluster
``` linkerd check --pre ``` ## Get the YAML ``` linkerd install > ./kubernetes/servicemesh/linkerd/manifest/linkerd-edge-20.10.1.yaml ``` ## Install Linkerd ``` kubectl apply -f ./kubernetes/servicemesh/linkerd/manifest/linkerd-edge-20.10.1.yaml ``` Let's wait until all components are running ``` watch kubectl -n linkerd get pods kubectl -n linkerd get svc ``` ## Do a final check ``` linkerd check ``` ## The dashboard Let's access the `linkerd` dashboard via `port-forward` ``` kubectl -n linkerd port-forward svc/linkerd-web 8084 ``` # Mesh our video catalog services There are 2 ways to mesh: 1) We can add an annotation to your deployment to persist the mesh if our YAML is part of a GitOps flow: This is a more permanent solution: ``` template: metadata: annotations: linkerd.io/inject: enabled ``` 2) Or inject `linkerd` on the fly: This may only be temporary as your CI/CD system may roll out the previous YAML ``` kubectl get deploy NAME READY UP-TO-DATE AVAILABLE AGE playlists-api 1/1 1 1 8h playlists-db 1/1 1 1 8h videos-api 1/1 1 1 8h videos-db 1/1 1 1 8h videos-web 1/1 1 1 8h kubectl get deploy playlists-api -o yaml | linkerd inject - | kubectl apply -f - kubectl get deploy playlists-db -o yaml | linkerd inject - | kubectl apply -f - kubectl get deploy videos-api -o yaml | linkerd inject - | kubectl apply -f - kubectl get deploy videos-db -o yaml | linkerd inject - | kubectl apply -f - kubectl get deploy videos-web -o yaml | linkerd inject - | kubectl apply -f - kubectl -n ingress-nginx get deploy nginx-ingress-controller -o yaml | linkerd inject - | kubectl apply -f - ``` # Generate some traffic Let's run a `curl` loop to generate some traffic to our site
We'll make a call to `/home/` and to simulate the browser making a call to get the playlists,
we'll make a follow up call to `/api/playlists` ``` While ($true) { curl -UseBasicParsing http://servicemesh.demo/home/;curl -UseBasicParsing http://servicemesh.demo/api/playlists; Start-Sleep -Seconds 1;} linkerd -n default check --proxy linkerd -n default stat deploy ``` # Add Faulty behaviour in videos API ``` kubectl edit deploy videos-api #set environment FLAKY=true ``` # Service Profile ``` linkerd profile -n default videos-api --tap deploy/videos-api --tap-duration 10s ``` After crafting the `serviceprofile`, we can apply it using `kubectl` ``` kubectl apply -f kubernetes/servicemesh/linkerd/serviceprofiles/videos-api.yaml ``` We can see that service profile helps us add retry policies in place:
``` linkerd routes -n default deploy/playlists-api --to svc/videos-api -o wide linkerd top deploy/videos-api ``` # Mutual TLS We can validate if mTLS is working ``` /work # linkerd -n default edges deployment SRC DST SRC_NS DST_NS SECURED playlists-api videos-api default default √ linkerd-prometheus playlists-api linkerd default √ linkerd-prometheus playlists-db linkerd default √ linkerd-prometheus videos-api linkerd default √ linkerd-prometheus videos-db linkerd default √ linkerd-prometheus videos-web linkerd default √ linkerd-tap playlists-api linkerd default √ linkerd-tap playlists-db linkerd default √ linkerd-tap videos-api linkerd default √ linkerd-tap videos-db linkerd default √ linkerd-tap videos-web linkerd default √ linkerd -n default tap deploy ```