Kubernetes - instalare cluster

Postat la Tue 12 May 2020 in tutoriale

Instalarea cluster-ului Kubernetes este facila cu kubeadm

Clusterul este format din 3 instante - Ubuntu 18.04 LTS - pregatite cu`Ansible </articole/kubernetes-preparare-noduri-cu-ansible/>`_ astfel:

  • k8s-master - nod de administrare
  • k8s-slave1 - nod worker
  • k8s-slave2 - nod worker

Nodurile au fiecare o interfata interna (10.209.214.0/16) si un externa (192.168.25.0/16).

Clusterul este initiat pe k8s-master:

# kubeadm init --pod-network-cidr=10.180.0.0/16 --apiserver-cert-extra-sans 192.168.25.180
[init] Using Kubernetes version: v1.18.2
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.209.214.31 192.168.25.180]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [10.209.214.31 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [10.209.214.31 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
W0512 14:55:02.267212   19375 manifests.go:225] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[control-plane] Creating static Pod manifest for "kube-scheduler"
W0512 14:55:02.268448   19375 manifests.go:225] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 38.031506 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.18" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8s-master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node k8s-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 5ucugc.6tj2hgqgi85lgf94
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[kubelet-check] Initial timeout of 40s passed.
[kubelet-check] It seems like the kubelet isn't running or healthy.
[kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get http://localhost:10248/healthz: dial tcp 127.0.0.1:10248: connect: connection refused.
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 10.209.214.31:6443 --token 5ucugc.6tj2hgqgi85lgf94 \
--discovery-token-ca-cert-hash sha256:23d7fbbd736c8a06e8c66c8d132b1a6e131666571874602822f8e6f4412d1987

unde:

  • pod-network-cidr - clasa de retea ce va fi folosita de pod-uri (10.180.0.0/16)
  • apiserver-cert-extra-sans - domeniile/adresele suplimentare incluse in certificatul SSL generat (192.168.25.180).

Copiem fisierul de config admin.conf in directorul utilizatorului si care va fi utilizat de kubectl:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Nota daca fisierul este transferat pe statia locala, sa modificam daca este cazul linia (cu IP extern al nodului master):

server: https://192.168.25.180:6443

nu inainte sa ne asiguram ca portul 6443 este accesibil si securizat.

Instalam serviciul pentru reteaua interna. Am ales flannel.

# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
podsecuritypolicy.policy/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.apps/kube-flannel-ds-amd64 created
daemonset.apps/kube-flannel-ds-arm64 created
daemonset.apps/kube-flannel-ds-arm created
daemonset.apps/kube-flannel-ds-ppc64le created
daemonset.apps/kube-flannel-ds-s390x created

Verificam functionarea corecta a servciilor:

# kubectl get no,po -A -o wide
NAME              STATUS     ROLES    AGE   VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION     CONTAINER-RUNTIME
node/k8s-master   Ready      master   39m   v1.18.2   10.209.214.31    <none>        Ubuntu 18.04.4 LTS   5.3.0-51-generic   docker://19.3.8

NAMESPACE     NAME                                     READY   STATUS              RESTARTS   AGE   IP               NODE         NOMINATED NODE   READINESS GATES
kube-system   pod/coredns-66bff467f8-4tz99             1/1     Running             0          38m   10.180.0.2       k8s-master   <none>           <none>
kube-system   pod/coredns-66bff467f8-txqrb             1/1     Running             0          38m   10.180.0.3       k8s-master   <none>           <none>
kube-system   pod/etcd-k8s-master                      1/1     Running             0          39m   10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-apiserver-k8s-master            1/1     Running             0          39m   10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-controller-manager-k8s-master   1/1     Running             0          39m   10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-flannel-ds-amd64-8chrg          1/1     Running             0          12m   10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-proxy-t2kvh                     1/1     Running             0          38m   10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-scheduler-k8s-master            1/1     Running             0          39m   10.209.214.31    k8s-master   <none>           <none>

Acum puntem trece la configurarea nodurilor worker. Rulam pe fiecare nod

# kubeadm join 10.209.214.31:6443 --token 5ucugc.6tj2hgqgi85lgf94 \
--discovery-token-ca-cert-hash sha256:23d7fbbd736c8a06e8c66c8d132b1a6e131666571874602822f8e6f4412d1987
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.18" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

Verificam daca nodul este in cluster

# kubectl get no,po -A -o wide
NAME              STATUS     ROLES    AGE     VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION     CONTAINER-RUNTIME
node/k8s-master   Ready      master   46m     v1.18.2   10.209.214.31    <none>        Ubuntu 18.04.4 LTS   5.3.0-51-generic   docker://19.3.8
node/k8s-slave1   Ready      <none>   7m53s   v1.18.2   10.209.214.201   <none>        Ubuntu 18.04.4 LTS   5.3.0-51-generic   docker://19.3.8
node/k8s-slave2   Ready      <none>   2m13s   v1.18.2   10.209.214.112   <none>        Ubuntu 18.04.4 LTS   5.3.0-51-generic   docker://19.3.8

NAMESPACE     NAME                                     READY   STATUS    RESTARTS   AGE     IP               NODE         NOMINATED NODE   READINESS GATES
kube-system   pod/coredns-66bff467f8-4tz99             1/1     Running   0          46m     10.180.0.2       k8s-master   <none>           <none>
kube-system   pod/coredns-66bff467f8-txqrb             1/1     Running   0          46m     10.180.0.3       k8s-master   <none>           <none>
kube-system   pod/etcd-k8s-master                      1/1     Running   0          46m     10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-apiserver-k8s-master            1/1     Running   0          46m     10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-controller-manager-k8s-master   1/1     Running   0          46m     10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-flannel-ds-amd64-8chrg          1/1     Running   0          19m     10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-flannel-ds-amd64-9njz7          1/1     Running   0          92s     10.209.214.112   k8s-slave2   <none>           <none>
kube-system   pod/kube-flannel-ds-amd64-fbfxf          1/1     Running   0          7m53s   10.209.214.201   k8s-slave1   <none>           <none>
kube-system   pod/kube-proxy-j4m2l                     1/1     Running   0          7m53s   10.209.214.201   k8s-slave1   <none>           <none>
kube-system   pod/kube-proxy-t2kvh                     1/1     Running   0          46m     10.209.214.31    k8s-master   <none>           <none>
kube-system   pod/kube-proxy-xg6hn                     1/1     Running   0          92s     10.209.214.112   k8s-slave2   <none>           <none>
kube-system   pod/kube-scheduler-k8s-master            1/1     Running   0          46m     10.209.214.31    k8s-master   <none>           <none>

Acum ca avem clusterul instalat putem rula containerele dorite. Va doresc spor.