k8s self-signed certificate TLS

TLS self-signed certificate

TLS certificate used for communication, certificate k8s required components are:

Step 1: Install certificate generation tool cfssl

Prior to this need to create a directory to hold the installation tool mkdir ssl, the tool will be installed later moved to the respective directory. Easy to manage

wget https://pkg.cfssl.org/R1.2/cfssl_linux-amd64
wget https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64
wget https://pkg.cfssl.org/R1.2/cfssl-certinfo_linux-amd64
chmod +x cfssl-certinfo_linux-amd64 cfssljson_linux-amd64 cfssl_linux-amd64 
mv cfssl_linux-amd64 /usr/local/bin/cfssl
mv cfssljson_linux-amd64 /usr/local/bin/cfssljson
mv cfssl-certinfo_linux-amd64 /usr/local/bin/cfssl-certinfo

In the implementation of wget command, if not installed this tool wget will prompt command does not exist.

//执行命令安装wget工具
yum install -y wget

Step 2: Use cfssl -help to view command cfssl Tools Help

The third step: Use tools to generate the certificate cfssl

Generate a configuration file that can be modified according to the document to suit their needs

Certificate generation ca-config.json

cat << EOF | tee ca-config.json
{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "kubernetes": {
         "expiry": "87600h",
         "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"
        ]
      }
    }
  }
}
EOF

Generate csr.json file

Generating ca-csr.json certificate file

cfssl print-defaults csr > ca-csr.json

//修改内容为如下：
{
    "CN": "kubernetes",
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Chengdu",
            "ST": "Chengdu",
             "O": "k8s",
            "OU": "System"
        }
    ]
}

生成 ca-key.pem ca.pem.

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

Generate server-csr.json file

cat << EOF | tee server-csr.json
{
    "CN": "kubernetes",
    "hosts": [
    "172.16.163.131",
    "172.16.163.130",   
    "172.16.163.129",
    "kubernetes",
    "kubernetes.default",
    "kubernetes.default.svc",
    "kubernetes.default.svc.cluster",
    "kubernetes.default.svc.cluster.local"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Chengdu",
            "ST": "Chengdu",
            "O": "k8s",     
            "OU": "System"
        }
    ]
}
EOF

生成 server.pem, server-key.pem

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

Will complain when executing the above command

The reason given

{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "kubernetes": { //应该将ca-config.json文件的profiles改为kubernetes
         "expiry": "87600h",
         "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"
        ]
      }
    }
  }
}

Generating admin-csr.json file

cfssl print-defaults csr > admin-csr.json

We need to modify the above admin-csr.json the following:

{
    "CN": "admin",
    "hosts": [],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Chengdu",
            "ST": "Chengdu",
            "O": "system:masters",
            "OU": "System"
        }
    ]
}

The last generation admin certificate --- admin-key.pem, admin.pem

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

Generate a proxy

cfssl print-defaults csr > kube-proxy-csr.json

//将kube-proxy-csr.json修改为如下：
{
    "CN": "system:kube-proxy",
    "hosts": [],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Chengdu",
            "ST": "Chengdu",
        "O": "k8s",
        "OU": "System"
        }
    ]
}

//生成代理证书 kube-proxy-key.pem , kube-proxy.pem
cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=kubernetes kube-proxy-csr.json | cfssljson -bare kube-proxy

Finally .json filter out files outside of pem

ls | grep -v pem

Use the command ls | grep -v pem |xargs -i rm {}to delete other files in addition to the pem file.

This certificate is generated better.