Using kubeadm to build k8s cluster

1, Environmental preparation:

There are two Centos7 hosts, 166(master)167(node01). docker is installed on both hosts. The following operations are performed on both hosts.

Modify the contents of the / etc/hosts file

[zjin@master ~]$ cat /etc/hosts
10.3.4.166 master
10.3.4.167 node01

Disable firewall

[zjin@master ~]$ sudo systemctl stop firewalld
[zjin@master ~]$ sudo systemctl disable firewalld

Turn off selinux

cat /etc/selinux/config
SELINUX=disabled

Create the / etc/sysctl.d/k8s.conf file

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1

Then execute the following command:

[zjin@master ~]$ sudo modprobe br_netfilter
[zjin@master ~]$ sudo sysctl -p /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1

2, Pull image:

On the master:

docker pull akipa11/kube-apiserver-amd64:v1.10.0
docker pull akipa11/kube-scheduler-amd64:v1.10.0
docker pull akipa11/kube-controller-manager-amd64:v1.10.0
docker pull akipa11/kube-proxy-amd64:v1.10.0
docker pull akipa11/k8s-dns-kube-dns-amd64:1.14.8
docker pull akipa11/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker pull akipa11/k8s-dns-sidecar-amd64:1.14.8
docker pull akipa11/etcd-amd64:3.1.12
docker pull akipa11/flannel:v0.10.0-amd64
docker pull akipa11/pause-amd64:3.1

docker tag akipa11/kube-apiserver-amd64:v1.10.0 k8s.gcr.io/kube-apiserver-amd64:v1.10.0
docker tag akipa11/kube-scheduler-amd64:v1.10.0 k8s.gcr.io/kube-scheduler-amd64:v1.10.0
docker tag akipa11/kube-controller-manager-amd64:v1.10.0 k8s.gcr.io/kube-controller-manager-amd64:v1.10.0
docker tag akipa11/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0
docker tag akipa11/k8s-dns-kube-dns-amd64:1.14.8 k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8
docker tag akipa11/k8s-dns-dnsmasq-nanny-amd64:1.14.8 k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker tag akipa11/k8s-dns-sidecar-amd64:1.14.8 k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8
docker tag akipa11/etcd-amd64:3.1.12 k8s.gcr.io/etcd-amd64:3.1.12
docker tag akipa11/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker tag akipa11/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1

On node01:

docker pull akipa11/kube-proxy-amd64:v1.10.0
docker pull akipa11/flannel:v0.10.0-amd64
docker pull akipa11/pause-amd64:3.1
docker pull akipa11/kubernetes-dashboard-amd64:v1.8.3
docker pull akipa11/heapster-influxdb-amd64:v1.3.3
docker pull akipa11/heapster-grafana-amd64:v4.4.3
docker pull akipa11/heapster-amd64:v1.4.2
docker pull akipa11/k8s-dns-kube-dns-amd64:1.14.8
docker pull akipa11/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker pull akipa11/k8s-dns-sidecar-amd64:1.14.8

docker tag akipa11/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker tag akipa11/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1
docker tag akipa11/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0

docker tag akipa11/k8s-dns-kube-dns-amd64:1.14.8 k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8
docker tag akipa11/k8s-dns-dnsmasq-nanny-amd64:1.14.8 k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker tag akipa11/k8s-dns-sidecar-amd64:1.14.8 k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8

docker tag akipa11/kubernetes-dashboard-amd64:v1.8.3 k8s.gcr.io/kubernetes-dashboard-amd64:v1.8.3
docker tag akipa11/heapster-influxdb-amd64:v1.3.3 k8s.gcr.io/heapster-influxdb-amd64:v1.3.3
docker tag akipa11/heapster-grafana-amd64:v4.4.3 k8s.gcr.io/heapster-grafana-amd64:v4.4.3
docker tag akipa11/heapster-amd64:v1.4.2 k8s.gcr.io/heapster-amd64:v1.4.2

3, Install kubeadm, kubelet, kubectl

1. Configure yum source:

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
        http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

2. Install kubeadm, kubelet, kubectl

The versions we installed here are all 1.10.0-0

$ yum makecache fast 
$ yum install -y kubelet-1.10.0-0
$ yum install -y kubectl-1.10.0-0
$ yum install -y kubeadm-1.10.0-0

3. Configure kubelet

• Modify parameters of CGroup driver

  Modify the configuration file / etc / system D / system / kubelet.service.d/10-kubeladm.conf of the file kubelet, and change the kubelet_cgroup_argsparameter to cgroupfs

• Add configuration parameters of swap

  Before ExecStart, add the following:

  Environment="KUBELET_EXTRA_ARGS=--fail-swap-on=false"
  

Finally, reload the configuration file

systemctl daemon-reload

4, Cluster installation initialization

Execute the following command on the master:

[zjin@master ~]$ sudo kubeadm init \
> --kubernetes-version=v1.10.0 \
> --pod-network-cidr=10.244.0.0/16 \
> --apiserver-advertise-address=10.3.4.166 \
> --ignore-preflight-errors=Swap

Cluster initialization command: kubeadm init, the later parameter is the cluster version to be installed. Because we select flannel as the network plug-in of Pod, we need to specify - Pod network CIDR = 10.244.0.0/16, then the communication address of apiserver. Here is the IP address of our master node, and - ignore preflight errors = swap means ignore swap Error message for.

Finally, we can see the successful information of cluster installation:

Your Kubernetes master 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/

You can now join any number of machines by running the following on each node
as root:

  kubeadm join 10.3.4.166:6443 --token b9ftqo.6a3igsfxq96b1dt6 --discovery-token-ca-cert-hash sha256:d4517be6c40e40e1bbc749b24b35c0a7f68c0f75c1380c32b24d1ccb42e0decc

Enter the following command to configure using kubectl to access the cluster:

[zjin@master ~]$ sudo mkdir -p $HOME/.kube
[zjin@master ~]$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[zjin@master ~]$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

After kubectl is configured, we can use kubectl to view cluster related information:

[zjin@master ~]$ kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok                   
scheduler            Healthy   ok                   
etcd-0               Healthy   {"health": "true"}   
[zjin@master ~]$ kubectl get csr
NAME        AGE       REQUESTOR            CONDITION
csr-nff2l   6m        system:node:master   Approved,Issued

If you encounter errors during cluster installation, you can use the following command to reset:

$ kubeadm reset
$ ifconfig cni0 down && ip link delete cni0
$ ifconfig flannel.1 down && ip link delete flannel.1
$ rm -rf /var/lib/cni/

5, Install pod network

Here we install the flannel network plug-in.

wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Note that the inage version number of the file content should be changed to v0.10.0

[zjin@master ~]$ kubectl apply -f 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

After the installation, we can use the kubectl get pods command to view the running status of the components in the cluster:

[zjin@master ~]$ kubectl get pods --all-namespaces
NAMESPACE     NAME                             READY     STATUS    RESTARTS   AGE
kube-system   etcd-master                      1/1       Running   0          40s
kube-system   kube-apiserver-master            1/1       Running   0          40s
kube-system   kube-controller-manager-master   1/1       Running   0          40s
kube-system   kube-dns-86f4d74b45-4vbx5        3/3       Running   0          12m
kube-system   kube-flannel-ds-amd64-wskq5      1/1       Running   0          52s
kube-system   kube-proxy-7dk2l                 1/1       Running   0          12m
kube-system   kube-scheduler-master            1/1       Running   0          40s

As you can see, all are Running.

6, Add node

Install docker, kubeadm, kubelet, kubectl with the same version number on node01(167), and then execute the following command:

[zjin@node01 ~]$ sudo kubeadm join 10.3.4.166:6443 --token ebimj5.91xj7atpxbke4x        yz --discovery-token-ca-cert-hash sha256:1eda2afcd5711343714ec2d2b6c6ea73ec06737        ee350b229d5b2eebfd82fb58a --ignore-preflight-errors=Swap

If an error is reported:

[preflight] Some fatal errors occurred:
        [ERROR CRI]: unable to check if the container runtime at "/var/run/docke        rshim.sock" is running: fork/exec /bin/crictl -r /var/run/dockershim.sock info:         no such file or directory

This is an error caused by the CRI tools version. You can uninstall CRI tools to solve this problem.

yum remove cri-tools

Then execute the command to join the node:

[zjin@node01 ~]$ sudo kubeadm join 10.3.4.166:6443 --token ebimj5.91xj7atpxbke4x        yz --discovery-token-ca-cert-hash sha256:1eda2afcd5711343714ec2d2b6c6ea73ec06737        ee350b229d5b2eebfd82fb58a --ignore-preflight-errors=Swap
[preflight] Running pre-flight checks.
        [WARNING SystemVerification]: docker version is greater than the most re        cently validated version. Docker version: 18.03.0-ce. Max validated version: 17.        03
        [WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[discovery] Trying to connect to API Server "10.3.4.166:6443"
[discovery] Created cluster-info discovery client, requesting info from "https:/        /10.3.4.166:6443"
[discovery] Requesting info from "https://10.3.4.166:6443" again to validate TLS         against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate va        lidates against pinned roots, will use API Server "10.3.4.166:6443"
[discovery] Successfully established connection with API Server "10.3.4.166:6443        "

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

Run 'kubectl get nodes' on the master to see this node join the cluster.

Then copy the ~ /. kube/config file of the master node to the corresponding location of the current node to use the kubectl command line tool.

[zjin@master ~]$ kubectl get nodes
NAME      STATUS    ROLES     AGE       VERSION
master    Ready     master    47m       v1.10.0
node01    Ready     <none>    3m        v1.10.0

As you can see, node01 has also joined the cluster.