MULTICLUSTER WITH LINKERD – PART 3

Part 2

Installing Linkerd and its family that will help us with MultiCluster

First of all, we need to create the certificate chain for Linkerd, which will be installed on all clusters equally:

mkdir certs && cd certs

step certificate create root.linkerd.cluster.local ca.crt ca.key \

   --profile root-ca \

   --no-password \

   --insecure

step certificate create identity.linkerd.cluster.local \

   issuer.crt issuer.key \

   --profile intermediate-ca --not-after 8760h \

   --no-password --insecure --ca ca.crt --ca-key ca.key

Keep the certificates safe; they are a core part of your Linkerd setup. If you lose them, you will have to reinstall and restart the pods that are in the mesh.

Run these instructions here while still in the certs directory with the certificates created:

alias linkerd='linkerd'

for ctx in kind-demo kind-demo3; do                   

    echo "install crds ${ctx}"                                                                                                                                                         

    linkerd install --context=${ctx} --crds | kubectl apply -f - --context=${ctx};

    echo "install linkerd ${ctx}";

    linkerd install --context=${ctx} \

      --identity-trust-anchors-file=ca.crt \

      --identity-issuer-certificate-file=issuer.crt \

      --identity-issuer-key-file=issuer.key | kubectl apply -f - --context=${ctx};

    echo "install viz ${ctx}";

    linkerd --context=${ctx} viz install | kubectl apply -f - --context=${ctx};

    echo "install multicluster ${ctx}";    

    linkerd --context=${ctx} multicluster install | kubectl apply -f - --context=${ctx};

    echo "install smi ${ctx}";        

    linkerd smi install --context=${ctx}  | kubectl apply -f - --context=${ctx};

Done

Check if your linkerd-multicluster received a LoadBalancer IP and run a telnet to them just to validate

for ctx in kind-demo kind-demo3; do

  printf "Checking cluster: ${ctx} ........."

  while [ "$(kubectl --context=${ctx} -n linkerd-multicluster get service linkerd-gateway -o 'custom-columns=:.status.loadBalancer.ingress[0].ip' --no-headers)" = "<none>" ]; do

      printf '.'

      sleep 1

  done

  echo "`kubectl --context=${ctx} -n linkerd-multicluster get service linkerd-gateway -o 'custom-columns=:.status.loadBalancer.ingress[0].ip' --no-headers`"

  printf "\n"

done

Time to link the clusters

This is when Linkerd creates service accounts in both clusters, generates a secret with the kubeconfig of each one cross-referenced, and voilà!

linkerd --context=kind-demo multicluster link --cluster-name kind-demo | kubectl apply -f - --context=kind-demo3

linkerd --context=kind-demo3 multicluster link --cluster-name kind-demo3 | kubectl apply -f - --context=kind-demo

Shall we see?

for ctx in kind-demo kind-demo3; do

  echo "Checking link....${ctx}"

  linkerd --context=${ctx} multicluster check

  echo "Checking gateways ...${ctx}"

  linkerd --context=${ctx} multicluster gateways

  echo "..............done ${ctx}"

done

Stay tuned, we will publish part 4 soon!