Deploying a Node Component

This section uses the k8snode1 node as an example.

Environment Preparation

# A proxy needs to be configured for the intranet.
$ dnf install -y docker iSulad conntrack-tools socat containernetworking-plugins
$ swapoff -a
$ mkdir -p /etc/kubernetes/pki/
$ mkdir -p /etc/cni/net.d
$ mkdir -p /opt/cni
# Delete the default kubeconfig file.
$ rm /etc/kubernetes/kubelet.kubeconfig

## Use iSulad as the runtime ########.
# Configure the iSulad.
cat  /etc/isulad/daemon.json
{
        "registry-mirrors": [
                "docker.io"
        ],
        "insecure-registries": [
                "k8s.gcr.io",
                "quay.io"
        ],
        "pod-sandbox-image": "k8s.gcr.io/pause:3.2",# pause type
        "network-plugin": "cni", # If this parameter is left blank, the CNI network plug-in is disabled. In this case, the following two paths become invalid. After the plug-in is installed, restart iSulad.
        "cni-bin-dir": "/usr/libexec/cni/",
        "cni-conf-dir": "/etc/cni/net.d",
}

# Add the proxy to the iSulad environment variable and download the image.
cat /usr/lib/systemd/system/isulad.service
[Service]
Type=notify
Environment="HTTP_PROXY=http://name:password@proxy:8080"
Environment="HTTPS_PROXY=http://name:password@proxy:8080"

# Restart the iSulad and set it to start automatically upon power-on.
systemctl daemon-reload
systemctl restart isulad




## If Docker is used as the runtime, run the following command: ########
$ dnf install -y docker
# If a proxy environment is required, configure a proxy for Docker, add the configuration file http-proxy.conf, and edit the following content. Replace name, password, and proxy-addr with the actual values.
$ cat /etc/systemd/system/docker.service.d/http-proxy.conf
[Service]
Environment="HTTP_PROXY=http://name:password@proxy-addr:8080"
$ systemctl daemon-reload
$ systemctl restart docker

Creating kubeconfig Configuration Files

Perform the following operations on each node to create a configuration file:

$ kubectl config set-cluster openeuler-k8s \
    --certificate-authority=/etc/kubernetes/pki/ca.pem \
    --embed-certs=true \
    --server=https://192.168.122.154:6443 \
    --kubeconfig=k8snode1.kubeconfig

$ kubectl config set-credentials system:node:k8snode1 \
    --client-certificate=/etc/kubernetes/pki/k8snode1.pem \
    --client-key=/etc/kubernetes/pki/k8snode1-key.pem \
    --embed-certs=true \
    --kubeconfig=k8snode1.kubeconfig

$ kubectl config set-context default \
    --cluster=openeuler-k8s \
    --user=system:node:k8snode1 \
    --kubeconfig=k8snode1.kubeconfig

$ kubectl config use-context default --kubeconfig=k8snode1.kubeconfig

Note: Change k8snode1 to the corresponding node name.

Copying the Certificate

Similar to the control plane, all certificates, keys, and related configurations are stored in the /etc/kubernetes/pki/ directory.

$ ls /etc/kubernetes/pki/
ca.pem                 k8snode1.kubeconfig  kubelet_config.yaml     kube-proxy-key.pem     kube-proxy.pem
k8snode1-key.pem  k8snode1.pem         kube_proxy_config.yaml  kube-proxy.kubeconfig

CNI Network Configuration

containernetworking-plugins is used as the CNI plug-in used by kubelet. In the future, plug-ins such as calico and flannel can be introduced to enhance the network capability of the cluster.

# Bridge Network Configuration
$ cat /etc/cni/net.d/10-bridge.conf
{
  "cniVersion": "0.3.1",
  "name": "bridge",
  "type": "bridge",
  "bridge": "cnio0",
  "isGateway": true,
  "ipMasq": true,
  "ipam": {
    "type": "host-local",
    "subnet": "10.244.0.0/16",
    "gateway": "10.244.0.1"
  },
  "dns": {
    "nameservers": [
      "10.244.0.1"
    ]
  }
}

# Loopback Network Configuration
$ cat /etc/cni/net.d/99-loopback.conf
{
    "cniVersion": "0.3.1",
    "name": "lo",
    "type": "loopback"
}

Deploying the kubelet Service

Configuration File on Which Kubelet Depends

$ cat /etc/kubernetes/pki/kubelet_config.yaml
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
  anonymous:
    enabled: false
  webhook:
    enabled: true
  x509:
    clientCAFile: /etc/kubernetes/pki/ca.pem
authorization:
  mode: Webhook
clusterDNS:
- 10.32.0.10
clusterDomain: cluster.local
runtimeRequestTimeout: "15m"
tlsCertFile: "/etc/kubernetes/pki/k8snode1.pem"
tlsPrivateKeyFile: "/etc/kubernetes/pki/k8snode1-key.pem"

Note: The IP address of the cluster DNS is 10.32.0.10, which must be the same as the value of service-cluster-ip-range.

Compiling the systemd Configuration File

$ cat /usr/lib/systemd/system/kubelet.service
[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=https://kubernetes.io/docs/
Wants=network-online.target
After=network-online.target

[Service]
ExecStartPre=swapoff -a
ExecStart=/usr/bin/kubelet \
	--config=/etc/kubernetes/pki/kubelet_config.yaml \
	--network-plugin=cni \
	--pod-infra-container-image=k8s.gcr.io/pause:3.2 \
	--kubeconfig=/etc/kubernetes/pki/k8snode1.kubeconfig \
	--register-node=true \
	--hostname-override=k8snode1 \
	--cni-bin-dir="/usr/libexec/cni,/opt/cni/bin" \
	--v=2

Restart=always
StartLimitInterval=0
RestartSec=10

[Install]
WantedBy=multi-user.target

Note: If iSulad is used as the runtime, add the following configuration:

--container-runtime=remote \
--container-runtime-endpoint=unix:///var/run/isulad.sock \

Deploying kube-proxy

Configuration File on Which kube-proxy Depends

cat /etc/kubernetes/pki/kube_proxy_config.yaml
kind: KubeProxyConfiguration
apiVersion: kubeproxy.config.k8s.io/v1alpha1
clientConnection:
  kubeconfig: /etc/kubernetes/pki/kube-proxy.kubeconfig
clusterCIDR: 10.244.0.0/16
mode: "iptables"

Compiling the systemd Configuration File

$ cat /usr/lib/systemd/system/kube-proxy.service
[Unit]
Description=Kubernetes Kube-Proxy Server
Documentation=https://kubernetes.io/docs/reference/generated/kube-proxy/
After=network.target

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/proxy
ExecStart=/usr/bin/kube-proxy \
	    $KUBE_LOGTOSTDERR \
	    $KUBE_LOG_LEVEL \
	    --config=/etc/kubernetes/pki/kube_proxy_config.yaml \
	    --hostname-override=k8snode1 \
	    $KUBE_PROXY_ARGS
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

Starting a Component Service

$ systemctl enable kubelet kube-proxy
$ systemctl start kubelet kube-proxy

Deploy other nodes in sequence.

Verifying the Cluster Status

Wait for several minutes and run the following command to check the node status:

$ kubectl get nodes --kubeconfig /etc/kubernetes/pki/admin.kubeconfig
NAME            STATUS   ROLES    AGE   VERSION
k8snode1   Ready    <none>   17h   v1.20.2
k8snode2   Ready    <none>   19m   v1.20.2
k8snode3   Ready    <none>   12m   v1.20.2

Deploying coredns

coredns can be deployed on a node or master node. In this document, coredns is deployed on the k8snode1 node.

Compiling the coredns Configuration File

$ cat /etc/kubernetes/pki/dns/Corefile
.:53 {
    errors
    health {
      lameduck 5s
    }
    ready
    kubernetes cluster.local in-addr.arpa ip6.arpa {
      pods insecure
      endpoint https://192.168.122.154:6443
      tls /etc/kubernetes/pki/ca.pem /etc/kubernetes/pki/admin-key.pem /etc/kubernetes/pki/admin.pem
      kubeconfig /etc/kubernetes/pki/admin.kubeconfig default
      fallthrough in-addr.arpa ip6.arpa
    }
    prometheus :9153
    forward . /etc/resolv.conf {
      max_concurrent 1000
    }
    cache 30
    loop
    reload
    loadbalance
}

Note:

Listen to port 53.
Configure the Kubernetes plug-in, including the certificate and the URL of kube api.

Preparing the service File of systemd

cat /usr/lib/systemd/system/coredns.service
[Unit]
Description=Kubernetes Core DNS server
Documentation=https://github.com/coredns/coredns
After=network.target

[Service]
ExecStart=bash -c "KUBE_DNS_SERVICE_HOST=10.32.0.10 coredns -conf /etc/kubernetes/pki/dns/Corefile"

Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

Starting the Service

$ systemctl enable coredns
$ systemctl start coredns

Creating the Service Object of coredns

$ cat coredns_server.yaml
apiVersion: v1
kind: Service
metadata:
  name: kube-dns
  namespace: kube-system
  annotations:
    prometheus.io/port: "9153"
    prometheus.io/scrape: "true"
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    kubernetes.io/name: "CoreDNS"
spec:
  clusterIP: 10.32.0.10
  ports:
  - name: dns
    port: 53
    protocol: UDP
  - name: dns-tcp
    port: 53
    protocol: TCP
  - name: metrics
    port: 9153
    protocol: TCP

Creating the Endpoint Object of coredns

$ cat coredns_ep.yaml
apiVersion: v1
kind: Endpoints
metadata:
  name: kube-dns
  namespace: kube-system
subsets:
  - addresses:
      - ip: 192.168.122.157
    ports:
      - name: dns-tcp
        port: 53
        protocol: TCP
      - name: dns
        port: 53
        protocol: UDP
      - name: metrics
        port: 9153
        protocol: TCP

Confirming the coredns Service

# View the service object.
$ kubectl get service -n kube-system kube-dns
NAME       TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE
kube-dns   ClusterIP   10.32.0.10   <none>        53/UDP,53/TCP,9153/TCP   51m
# View the endpoint object.
$ kubectl get endpoints -n kube-system kube-dns
NAME       ENDPOINTS                                                    AGE
kube-dns   192.168.122.157:53,192.168.122.157:53,192.168.122.157:9153   52m

Deploying a Node Component

Environment Preparation

Creating kubeconfig Configuration Files

Copying the Certificate

CNI Network Configuration

Deploying the kubelet Service

Configuration File on Which Kubelet Depends

Compiling the systemd Configuration File

Deploying kube-proxy

Configuration File on Which kube-proxy Depends

Compiling the systemd Configuration File

Starting a Component Service

Verifying the Cluster Status

Deploying coredns

Compiling the coredns Configuration File

Preparing the service File of systemd

Starting the Service

Creating the Service Object of coredns

Creating the Endpoint Object of coredns

Confirming the coredns Service

Bug Catching

Buggy Content

Bug Description

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