Skip to content

Latest commit

 

History

History
420 lines (349 loc) · 8.77 KB

04.Certificate-Authority.md

File metadata and controls

420 lines (349 loc) · 8.77 KB
Raw

Provisioning a CA and Generating TLS Certificates

We will provision a PKI Infrastructure using CloudFlare's PKI toolkit, cfssl, then use it to bootstrap a Certificate Authority, and generate TLS certificates for the following components: etcd, kube-apiserver, kube-controller-manager, kube-scheduler, kubelet, and kube-proxy.

Certificate Authority

  • Generate CA default files (To understand the structure of CA and CSR json . We will overwrite this configs in next steps)
cfssl print-defaults config > ca-config.json
cfssl print-defaults csr > ca-csr.json
  • Modify ca-config and ca-csr to fit your requirement
cat <<EOF >ca-config.json
{
    "signing": {
        "default": {
            "expiry": "8760h"
        },
        "profiles": {
            "kubernetes": {
                "expiry": "8760h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth",
                    "client auth"
                ]
            }
        }
    }
}
EOF

cat <<EOF >ca-csr.json
{
    "CN": "Kubernetes",
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "IN",
            "L": "KL",
            "O": "Kubernetes",
            "OU": "CA",
            "ST": "Kerala"
        }
    ]
}
EOF

cfssl gencert -initca ca-csr.json |cfssljson -bare ca
  • Output
2018/10/01 22:03:14 [INFO] generating a new CA key and certificate from CSR
2018/10/01 22:03:14 [INFO] generate received request
2018/10/01 22:03:14 [INFO] received CSR
2018/10/01 22:03:14 [INFO] generating key: rsa-2048
2018/10/01 22:03:14 [INFO] encoded CSR
2018/10/01 22:03:14 [INFO] signed certificate with serial number 621260968886516247086480084671432552497699065843
  • ca.pem , ca-key.pem, ca.csr files will be created , but we need only ca.pem and ca-key.pem
k8s@lb-01:~$ ls -lrt ca*
-rw-rw-r-- 1 k8s k8s  385 Oct  1 21:53 ca-config.json
-rw-rw-r-- 1 k8s k8s  262 Oct  1 21:56 ca-csr.json
-rw-rw-r-- 1 k8s k8s 1350 Oct  1 22:03 ca.pem
-rw------- 1 k8s k8s 1679 Oct  1 22:03 ca-key.pem
-rw-r--r-- 1 k8s k8s  997 Oct  1 22:03 ca.csr

Client and Server Certificates

In this section you will generate client and server certificates for each Kubernetes component and a client certificate for the Kubernetes admin user.

The Admin Client Certificate

{

cat > admin-csr.json <<EOF
{
  "CN": "admin",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

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

}

Results:

admin-key.pem
admin.pem

The Kubelet Client Certificates

Kubernetes uses a special-purpose authorization mode called Node Authorizer, that specifically authorizes API requests made by Kubelets. In order to be authorized by the Node Authorizer, Kubelets must use a credential that identifies them as being in the system:nodes group, with a username of system:node:<nodeName>. In this section you will create a certificate for each Kubernetes worker node that meets the Node Authorizer requirements.

Generate a certificate and private key for each Kubernetes worker node:

for instance in worker-01 worker-02 worker-03; do
cat > ${instance}-csr.json <<EOF
{
  "CN": "system:node:${instance}",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:nodes",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

IP=$(echo -n ${instance} |tail -c 1 && echo) 
EXTERNAL_IP=192.168.78.21${IP}


cfssl gencert \
  -ca=ca.pem \
  -ca-key=ca-key.pem \
  -config=ca-config.json \
  -hostname=${instance},${EXTERNAL_IP} \
  -profile=kubernetes \
  ${instance}-csr.json | cfssljson -bare ${instance}
done

Results:

worker-01-key.pem
worker-01.pem
worker-02-key.pem
worker-02.pem
worker-03-key.pem
worker-03.pem

The Controller Manager Client Certificate

Generate the kube-controller-manager client certificate and private key:

{

cat > kube-controller-manager-csr.json <<EOF
{
  "CN": "system:kube-controller-manager",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

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

}

Results:

kube-controller-manager-key.pem
kube-controller-manager.pem

The Kube Proxy Client Certificate

Generate the kube-proxy client certificate and private key:

{

cat > kube-proxy-csr.json <<EOF
{
  "CN": "system:kube-proxy",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

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

}

Results:

kube-proxy-key.pem
kube-proxy.pem

The Scheduler Client Certificate

Generate the kube-scheduler client certificate and private key:

{

cat > kube-scheduler-csr.json <<EOF
{
  "CN": "system:kube-scheduler",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

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

}

Results:

kube-scheduler-key.pem
kube-scheduler.pem

The Kubernetes API Server Certificate

The kubernetes-the-hard-way static IP address will be included in the list of subject alternative names for the Kubernetes API Server certificate. This will ensure the certificate can be validated by remote clients.

Generate the Kubernetes API Server certificate and private key:

{

KUBERNETES_ADDRESS=172.168.0.1,192.168.78.201,192.168.78.202,192.168.78.203,192.168.78.225,192.168.78.226,192.168.78.220

cat > kubernetes-csr.json <<EOF
{
  "CN": "kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

cfssl gencert \
  -ca=ca.pem \
  -ca-key=ca-key.pem \
  -config=ca-config.json \
  -hostname=${KUBERNETES_ADDRESS},127.0.0.1,kubernetes.default \
  -profile=kubernetes \
  kubernetes-csr.json | cfssljson -bare kubernetes

}

Results:

kubernetes-key.pem
kubernetes.pem

The Service Account Key Pair

The Kubernetes Controller Manager leverages a key pair to generate and sign service account tokens as describe in the managing service accounts documentation.

Generate the service-account certificate and private key:

{

cat > service-account-csr.json <<EOF
{
  "CN": "service-accounts",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "IN",
      "L": "Bangalore",
      "O": "system:masters",
      "OU": "Kubernetes The Hard Way with vBox",
      "ST": "Karnataka"
    }
  ]
}
EOF

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

}

Results:

service-account-key.pem
service-account.pem

Distribute the Client and Server Certificates

Copy the appropriate certificates and private keys to each worker instance:

for instance in worker-01 worker-02 worker-03; do
  scp ca.pem ${instance}-key.pem ${instance}.pem ${instance}:~/
done

Copy the appropriate certificates and private keys to each controller instance:

for instance in controller-01 controller-02 controller-03; do
  scp ca.pem ca-key.pem kubernetes-key.pem kubernetes.pem \
    service-account-key.pem service-account.pem ${instance}:~/
done

The kube-proxy, kube-controller-manager, kube-scheduler, and kubelet client certificates will be used to generate client authentication configuration files in the next lab.

Part 5 - Kubernetes Configuration Files