①.cfssl 创建k8s证书

集群相关证书类型
client certificate：用于服务端认证客户端,例如etcdctl、etcd proxy、fleetctl、docker客户端
server certificate: 服务端使用，客户端以此验证服务端身份,例如docker服务端、kube-apiserver
peer certificate: 双向证书，用于etcd集群成员间通信

根据认证对象可以将证书分成三类：服务器证书server cert，客户端证书client cert，对等证书peer cert(表示既是server cert又是client cert)，在kubernetes 集群中需要的证书种类如下：

etcd 节点需要标识自己服务的server cert，也需要client cert与etcd集群其他节点交互，当然可以分别指定2个证书，也可以使用一个对等证书
master 节点需要标识 apiserver服务的server cert，也需要client cert连接etcd集群，这里也使用一个对等证书
kubectl calico kube-proxy 只需要client cert，因此证书请求中 hosts 字段可以为空
kubelet证书比较特殊，不是手动生成，它由node节点TLS BootStrap向apiserver请求，由master节点的controller-manager 自动签发，包含一个client cert 和一个server cert

0.安装cfssl工具并设定权限

wget -O /usr/bin/cfssl https://software.yangyijing.cn/kubernetes/cfssl/cfssl
wget -O /usr/bin/cfssl-json https://software.yangyijing.cn/kubernetes/cfssl/cfssl-json
wget -O /usr/bin/cfssl-certinfo https://software.yangyijing.cn/kubernetes/cfssl/cfssl-json
chmod +x /usr/bin/cfssl*
[root@rstx-53 test]# cfssl version
Version: 1.2.0
Revision: dev
Runtime: go1.6

示例

[root@rstx-53 test]# cfssl print-defaults csr
{
    "CN": "example.net",
    "hosts": [
        "example.net",
        "www.example.net"
    ],
    "key": {
        "algo": "ecdsa",
        "size": 256
    },
    "names": [
        {
            "C": "US",
            "L": "CA",
            "ST": "San Francisco"
        }
    ]
}

[root@rstx-53 test]# cfssl print-defaults config
{
    "signing": {
        "default": {
            "expiry": "168h"
        },
        "profiles": {
            "www": {
                "expiry": "8760h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth"
                ]
            },
            "client": {
                "expiry": "8760h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "client auth"
                ]
            }
        }
    }
}

1.生成根签名证书的请求文件(certificate signing request) ca-csr.json

cat > /opt/certs/ca-csr.json <<EOF
{
    "CN": "RSTX",
    "hosts": [
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "ST": "beijing",
            "L": "beijing",
            "O": "od",
            "OU": "ops"
        }
    ],
    "ca": {
        "expiry": "175200h"
    }
}
EOF

CN 是请求用户的用户名
O:是请求用户的组名
expiry 设置CA证书的签名请求文件有效期为 10年

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

上述命令会生成一个证书 ca.pem ,一个私钥 ca-key.pem,以及ca.csr (证书签名请求).
可以通过openssl来校验一个证书

openssl x509 -in ca.pem -text -noout

2.创建基于根证书的config配置文件 CA的配置文件

 vi /opt/certs/ca-config.json
{
    "signing": {
        "default": {
            "expiry": "175200h"
        },
        "profiles": {
            "server": {
                "expiry": "175200h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth"
                ]
            },
            "client": {
                "expiry": "175200h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "client auth"
                ]
            },
            "peer": {
                "expiry": "175200h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth",
                    "client auth"
                ]
            }
        }
    }
}

signing :表示可以签发证书
profiles:是证书的类型,本例中该证书用于签名,且是双向对等证书(server auth, client auth)

3.用CA证书为k8s-etcd用户签发一个证书及私钥

vi /opt/certs/etcd-peer-csr.json
{
    "CN": "k8s-etcd",
    "hosts": [
        "192.168.1.201",
        "192.168.1.202",
        "192.168.1.203",
        "192.168.1.204",
        "192.168.1.205"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "ST": "beijing",
            "L": "beijing",
            "O": "od",
            "OU": "ops"
        }
    ]
}

hosts字段包含etcd服务运行主机的ip地址填写ip段无效
生成etcd-peer.pem 及etcd-peer-key.pem证书

cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=peer etcd-peer-csr.json |cfssl-json -bare etcd-peer

检验etcd-peer.pem信息

cfssl-certinfo -cert etcd-peer.pem