README0.1.md

The IP address of pod can be fixed, and kubernetes dynamic IP network allocation management plug-in based on etcd distributed storage is used.kube-ipam allocates ip addresses out of a set of address ranges.It stores the state locally on the remote etcd, therefore ensuring uniqueness of IP addresses in a cluster.Optionally, it can include a DNS configuration from a resolv.conf file on the host.

1 Install kube-ipam：

kube-ipam binary program files can be obtained by download or compile, and copy the kube-ipam binary to the /opt/cni/bin/ directory

tar -zxvf kube-ipam-x86.tgz
mv kube-ipam /opt/cni/bin/kube-ipam

2 /etc/cni/net.d network configuration

2.1 Configure IP subnet and etcd storage

The IP subnet information of pod is set by subnet parameter, and the gateway of pod is set by gateway parameter.You can configure the etcd address and certificate to be stored in kubernetes pod IP address in etcdConfig parameter.

Edit /etc/cni/net.d/1-kube-ipam.conf files on all kubernetes node servers.

{
        "cniVersion":"0.3.1",
        "name": "k8snetwork",
        "type": "macvlan",
        "master": "eth1",
        "ipam": {
                "name": "kube-subnet",
                "type": "kube-ipam",
                "etcdConfig": {
                        "etcdURL": "https://192.168.1.50:2379",
                        "etcdCertFile": "/etc/kubernetes/ssl/etcd.pem",
                        "etcdKeyFile": "/etc/kubernetes/ssl/etcd-key.pem",
                        "etcdTrustedCAFileFile": "/etc/kubernetes/ssl/ca.pem"
                },
                "subnet": "10.188.0.0/16",
                "rangeStart": "10.188.0.10",
                "rangeEnd": "10.188.0.200",
                "gateway": "10.188.0.1",
                "routes": [{
                        "dst": "0.0.0.0/0"
                }],
                "resolvConf": "/etc/resolv.conf"
        }
}

2.2 Configuration parameter description

• type (string, required): fill in your CNI plug-in type, such as macvlan, ipvlan, kube-router, bridge, etc.
• routes (string, optional): list of routes to add to the container namespace. Each route is a dictionary with "dst" and optional "gw" fields. If "gw" is omitted, value of "gateway" will be used.
• resolvConf (string, optional): Path to a resolv.conf on the host to parse and return as the DNS configuration
• ranges, (array, required, nonempty) an array of arrays of range objects:
  • subnet (string, required): CIDR block to allocate out of.
  • rangeStart (string, optional): IP inside of "subnet" from which to start allocating addresses. Defaults to ".2" IP inside of the "subnet" block.
  • rangeEnd (string, optional): IP inside of "subnet" with which to end allocating addresses. Defaults to ".254" IP inside of the "subnet" block for ipv4, ".255" for IPv6
  • gateway (string, optional): IP inside of "subnet" to designate as the gateway. Defaults to ".1" IP inside of the "subnet" block.
• etcdConfig, an object of etcd address info
  • etcdURL (string, required): The URL of etcd
  • etcdCertFile (string, required): The cert file of etcd
  • etcdKeyFile (string, required): The key file of etcd
  • etcdTrustedCAFileFile (string, required): The ca file of etcd

3 Kubernetes fixed pod IP address

3.1 Fixed pod IP configuration

The fixed allocation of pod IP address can be realized by configuring kube-ipam.ip, kube-ipam.netmask and kube-ipam.gateway parameters in annotations.
In /etc/cni/net.d/1-kube-ipam.conf,The range of the pod IP address is set in rangestart and rangeend.But if you need to keep the pod IP address fixed, please do not set the value of kube-ipam.ip within this range.
Edit fixed-ip-test-Deployment.yaml , which is used to create a fixed IP pod:

# cat fixed-ip-test-Deployment.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: fixed-ip-test
  namespace: default
  labels:
    k8s-app: cloudnativer-test
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
  selector:
    matchLabels:
      k8s-app: cloudnativer-test
  template:
    metadata:
      labels:
        k8s-app: cloudnativer-test
      annotations:
        kube-ipam.ip: "10.188.0.216"
        kube-ipam.netmask: "255.255.0.0"
        kube-ipam.gateway: "10.188.0.1"
    spec:
      containers:
      - name: fixed-ip-test
        image: nginx:1.7.9
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 80  
---

Note that at present, Kube-ipam only supports the fixed IPv4 address, and we will provide the fixed IPv6 address function in the future.

3.2 Create a fixed IP pod

Use the kubectl apply command to create a fixed IP pod:

# kubectl apply -f fixed-ip-test-Deployment.yaml
#
# kubectl get pod -o wide
  NAME                             READY   STATUS    RESTARTS   AGE     IP             NODE   
  fixed-ip-test-6d9b74fd4d-dbbsd   1/1     Running   0          2d23h   10.188.0.216   192.168.1.66

At this point, the fixed-ip-test-6d9b74fd4d-dbbsd is fixed to 10.188.0.216.

3.3 After rescheduling, the pod IP remains unchanged

Use the kubectl delete command to delete this pod, and kuberntes will automatically start a new fixed IP test pod:

# kubectl delete pod fixed-ip-test-6d9b74fd4d-dbbsd
#
# kubectl get pod -o wide
  NAME                             READY   STATUS    RESTARTS   AGE   IP             NODE   
  fixed-ip-test-6d9b74fd4d-xjhek   1/1     Running   0          1h    10.188.0.216   192.168.1.66

At this time, the IP address of the newly started fixed-ip-test-6d9b74fd4d-xjhek is still 10.188.0.216.