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Preparing Certificates

Preparing Certificates ​

Statement: The certificate used in this document is self-signed and cannot be used in a commercial environment.

Before deploying a cluster, you need to generate certificates required for communication between components in the cluster. This document uses the open-source CFSSL as the verification and deployment tool to help users understand the certificate configuration and the association between certificates of cluster components. You can select a tool based on the site requirements, for example, OpenSSL.

Building and Installing CFSSL ​

The following commands for building and installing CFSSL are for your reference (the CFSSL website access permission is required, and the proxy must be configured first):

bash
wget --no-check-certificate  https://github.com/cloudflare/cfssl/archive/v1.5.0.tar.gz
tar -zxf v1.5.0.tar.gz
cd cfssl-1.5.0/
make -j6
cp bin/* /usr/local/bin/

Generating a Root Certificate ​

Compile the CA configuration file, for example, ca-config.json:

bash
$ cat ca-config.json | jq
{
  "signing": {
    "default": {
      "expiry": "8760h"
    },
    "profiles": {
      "kubernetes": {
        "usages": [
          "signing",
          "key encipherment",
          "server auth",
          "client auth"
        ],
        "expiry": "8760h"
      }
    }
  }
}

Compile a CA CSR file, for example, ca-csr.json:

bash
$ cat ca-csr.json  | jq
{
  "CN": "Kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "openEuler",
      "OU": "WWW",
      "ST": "BinJiang"
    }
  ]
}

Generate the CA certificate and key:

bash
cfssl gencert -initca ca-csr.json | cfssljson -bare ca

The following certificates are obtained:

bash
ca.csr  ca-key.pem  ca.pem

Generating the admin Account Certificate ​

admin is an account used by K8S for system management. Compile the CSR configuration of the admin account, for example, admin-csr.json:

bash
cat admin-csr.json | jq
{
  "CN": "admin",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:masters",
      "OU": "Containerum",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=kubernetes admin-csr.json | cfssljson -bare admin

The result is as follows:

bash
admin.csr  admin-key.pem  admin.pem

Generating a service-account Certificate ​

Compile the CSR configuration file of the service-account account, for example, service-account-csr.json:

bash
cat service-account-csr.json | jq
{
  "CN": "service-accounts",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "Kubernetes",
      "OU": "openEuler k8s install",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -profile=kubernetes service-account-csr.json | cfssljson -bare service-account

The result is as follows:

bash
service-account.csr  service-account-key.pem  service-account.pem

Generating the kube-controller-manager Certificate ​

Compile the CSR configuration of kube-controller-manager:

bash
{
  "CN": "system:kube-controller-manager",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:kube-controller-manager",
      "OU": "openEuler k8s kcm",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -profile=kubernetes kube-controller-manager-csr.json | cfssljson -bare kube-controller-manager

The result is as follows:

bash
kube-controller-manager.csr  kube-controller-manager-key.pem  kube-controller-manager.pem

Generating the kube-proxy Certificate ​

Compile the CSR configuration of kube-proxy:

bash
{
  "CN": "system:kube-proxy",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:node-proxier",
      "OU": "openEuler k8s kube proxy",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -profile=kubernetes kube-proxy-csr.json | cfssljson -bare kube-proxy

The result is as follows:

bash
kube-proxy.csr  kube-proxy-key.pem  kube-proxy.pem

Generating the kube-scheduler Certificate ​

Compile the CSR configuration of kube-scheduler:

bash
{
  "CN": "system:kube-scheduler",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:kube-scheduler",
      "OU": "openEuler k8s kube scheduler",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -profile=kubernetes kube-scheduler-csr.json | cfssljson -bare kube-scheduler

The result is as follows:

bash
kube-scheduler.csr  kube-scheduler-key.pem  kube-scheduler.pem

Generating the kubelet Certificate ​

The certificate involves the host name and IP address of the server where kubelet is located. Therefore, the configuration of each node is different. The script is compiled as follows:

bash
$ cat node_csr_gen.bash

#!/bin/bash

nodes=(k8snode1 k8snode2 k8snode3)
IPs=("192.168.122.157" "192.168.122.158" "192.168.122.159")

for i in "${!nodes[@]}"; do

cat > "${nodes[$i]}-csr.json" <<EOF
{
  "CN": "system:node:${nodes[$i]}",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:nodes",
      "OU": "openEuler k8s kubelet",
      "ST": "BinJiang"
    }
  ]
}
EOF

 # generate ca
 echo "generate: ${nodes[$i]} ${IPs[$i]}"
 cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -hostname=${nodes[$i]},${IPs[$i]} -profile=kubernetes ${nodes[$i]}-csr.json | cfssljson -bare ${nodes[$i]}
done

Note: If a node has multiple IP addresses or other aliases, you can add other IP addresses or host names to -hostname.

The result is as follows:

bash
k8snode1.csr       k8snode1.pem       k8snode2-key.pem  k8snode3-csr.json
k8snode1-csr.json  k8snode2.csr       k8snode2.pem      k8snode3-key.pem
k8snode1-key.pem   k8snode2-csr.json  k8snode3.csr      k8snode3.pem

CSR configuration information. The following uses k8snode1 as an example:

bash
$ cat k8snode1-csr.json
{
  "CN": "system:node:k8snode1",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "system:nodes",
      "OU": "openEuler k8s kubelet",
      "ST": "BinJiang"
    }
  ]
}

Note: The account group to which each node belongs is system:node. Therefore, the CN field of CSR is system:node plus hostname.

Generating the kube-apiserver Certificate ​

Compile the CSR configuration file of kube api server:

bash
$ cat kubernetes-csr.json | jq
{
  "CN": "kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "Kubernetes",
      "OU": "openEuler k8s kube api server",
      "ST": "BinJiang"
    }
  ]
}

Generate the certificate and key:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -hostname=10.32.0.1,192.168.122.154,192.168.122.155,192.168.122.156,127.0.0.1,kubernetes,kubernetes.default,kubernetes.default.svc,kubernetes.default.svc.cluster,kubernetes.svc.cluster.local -profile=kubernetes kubernetes-csr.json | cfssljson -bare kubernetes

The result is as follows:

bash
kubernetes.csr  kubernetes-key.pem  kubernetes.pem

Note: 10.32.0.1 is an IP address within the range used by internal services. You can set it to other values. This parameter will be set when the apiserver service is started.

Generating the ETCD Certificate ​

ETCD can be deployed in either of the following ways:

  • Start an ETCD service on each api-server.
  • Independently deploy an ETCD cluster service.

If the certificate is deployed together with api-server, use the kubernetes-key.pem and kubernetes.pem certificates generated in the preceding steps.

For an independent ETCD cluster, you need to create the following certificates:

Compile the CSR configuration of ETCD:

bash
cat etcd-csr.json | jq
{
  "CN": "ETCD",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "L": "HangZhou",
      "O": "ETCD",
      "OU": "openEuler k8s etcd",
      "ST": "BinJiang"
    }
  ]
}

Generate a certificate:

bash
cfssl gencert -ca=../ca/ca.pem -ca-key=../ca/ca-key.pem -config=../ca/ca-config.json -hostname=192.168.122.154,192.168.122.155,192.168.122.156,127.0.0.1 -profile=kubernetes etcd-csr.json | cfssljson -bare etcd
  • Note: Assume that the IP address of the ETCD cluster is 192.168.122.154,192.168.122.155,192.168.122.156*

The result is as follows:

bash
etcd.csr  etcd-key.pem  etcd.pem
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Licensed underthe MulanPSL2
Copyright © 2025 openEuler. All rights reserved.
J. ICP B. No. 2020036654-1J.G.W.A.B. No. 11030102011597