Install CNI plugin

Kubernetes uses the Container Network Interface (CNI) to interact with networking providers like Calico. The Calico binary that presents this API to Kubernetes is called the CNI plugin and must be installed on every node in the Kubernetes cluster.

Provision Kubernetes user account for the plugin

The CNI plugin interacts with the Kubernetes API server while creating pods, both to obtain additional information and to update the datastore with information about the pod.

On the Kubernetes master node, create a key for the CNI plugin to authenticate with and certificate signing request.

openssl req -newkey rsa:4096 \
           -keyout cni.key \
           -nodes \
           -out cni.csr \
           -subj "/CN=calico-cni"

We will sign this certificate using the main Kubernetes CA.

sudo openssl x509 -req -in cni.csr \
                  -CA /etc/kubernetes/pki/ca.crt \
                  -CAkey /etc/kubernetes/pki/ca.key \
                  -CAcreateserial \
                  -out cni.crt \
                  -days 365
sudo chown ubuntu:ubuntu cni.crt

Next, we create a kubeconfig file for the CNI plugin to use to access Kubernetes.

APISERVER=$(kubectl config view -o jsonpath='{.clusters[0].cluster.server}')
kubectl config set-cluster kubernetes \
    --certificate-authority=/etc/kubernetes/pki/ca.crt \
    --embed-certs=true \
    --server=$APISERVER \
    --kubeconfig=cni.kubeconfig

kubectl config set-credentials calico-cni \
    --client-certificate=cni.crt \
    --client-key=cni.key \
    --embed-certs=true \
    --kubeconfig=cni.kubeconfig

kubectl config set-context default \
    --cluster=kubernetes \
    --user=calico-cni \
    --kubeconfig=cni.kubeconfig

kubectl config use-context default --kubeconfig=cni.kubeconfig

Copy this cni.kubeconfig file to every node in the cluster.

Provision RBAC

Define a cluster role the CNI plugin will use to access Kubernetes.

kubectl apply -f - <<EOF
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: calico-cni
rules:
  # The CNI plugin needs to get pods, nodes, and namespaces.
  - apiGroups: [""]
    resources:
      - pods
      - nodes
      - namespaces
    verbs:
      - get
  # The CNI plugin patches pods/status.
  - apiGroups: [""]
    resources:
      - pods/status
    verbs:
      - patch
 # These permissions are required for Calico CNI to perform IPAM allocations.
  - apiGroups: ["crd.projectcalico.org"]
    resources:
      - blockaffinities
      - ipamblocks
      - ipamhandles
    verbs:
      - get
      - list
      - create
      - update
      - delete
  - apiGroups: ["crd.projectcalico.org"]
    resources:
      - ipamconfigs
      - clusterinformations
      - ippools
    verbs:
      - get
      - list
EOF

Bind the cluster role to the calico-cni account.

kubectl create clusterrolebinding calico-cni --clusterrole=calico-cni --user=calico-cni

Install the plugin

Do these steps on each node in your cluster.

Run these commands as root.

sudo su

Install the CNI plugin Binaries

curl -L -o /opt/cni/bin/calico https://github.com/projectcalico/cni-plugin/releases/download/v3.8.0/calico-amd64
chmod 755 /opt/cni/bin/calico
curl -L -o /opt/cni/bin/calico-ipam https://github.com/projectcalico/cni-plugin/releases/download/v3.8.0/calico-ipam-amd64
chmod 755 /opt/cni/bin/calico-ipam

Create the config directory

mkdir -p /etc/cni/net.d/

Copy the kubeconfig from the previous section

cp cni.kubeconfig /etc/cni/net.d/calico-kubeconfig
chmod 600 /etc/cni/net.d/calico-kubeconfig

Write the CNI configuration

cat > /etc/cni/net.d/10-calico.conflist <<EOF
{
  "name": "k8s-pod-network",
  "cniVersion": "0.3.1",
  "plugins": [
    {
      "type": "calico",
      "log_level": "info",
      "datastore_type": "kubernetes",
      "mtu": 1500,
      "ipam": {
          "type": "calico-ipam"
      },
      "policy": {
          "type": "k8s"
      },
      "kubernetes": {
          "kubeconfig": "/etc/cni/net.d/calico-kubeconfig"
      }
    },
    {
      "type": "portmap",
      "snat": true,
      "capabilities": {"portMappings": true}
    }
  ]
}
EOF

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