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Creating a Certificate Authority and TLS Certificates for Kubernetes

The various components of Kubernetes require certificates in order to authenticate with one another. Provisioning a certificate authority and using it to generate those certificates is a necessary step in bootstrapping a Kubernetes cluster from scratch. This activity will guide you through the process of provisioning a certificate authority and generating the certificates Kubernetes needs.

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Path Info

Level

Intermediate

Duration

1h 0m

Published

Sep 28, 2018

Challenge

Provision the certificate authority (CA).

You can provision the certificate authority like so:

{

cat > ca-config.json << EOF
{
  "signing": {
    "default": {
      "expiry": "8760h"
    },
    "profiles": {
      "kubernetes": {
        "usages": ["signing", "key encipherment", "server auth", "client auth"],
        "expiry": "8760h"
      }
    }
  }
}
EOF

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

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

}

Challenge

Generate the necessary Kubernetes client certs, as well as kubelet client certs for two worker nodes.

Use these commands to generate the client certs.

Admin client cert:

{

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

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

}

Kubelet client certs:

{
cat > worker0.mylabserver.com-csr.json << EOF
{
  "CN": "system:node:worker0.mylabserver.com",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:nodes",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
EOF

cfssl gencert 
  -ca=ca.pem 
  -ca-key=ca-key.pem 
  -config=ca-config.json 
  -hostname=172.34.1.0,worker0.mylabserver.com 
  -profile=kubernetes 
  worker0.mylabserver.com-csr.json | cfssljson -bare worker0.mylabserver.com

cat > worker1.mylabserver.com-csr.json << EOF
{
  "CN": "system:node:worker1.mylabserver.com",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:nodes",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
EOF

cfssl gencert 
  -ca=ca.pem 
  -ca-key=ca-key.pem 
  -config=ca-config.json 
  -hostname=172.34.1.1,worker1.mylabserver.com 
  -profile=kubernetes 
  worker1.mylabserver.com-csr.json | cfssljson -bare worker1.mylabserver.com

}

Kube Controller Manager client cert:

{

cat > kube-controller-manager-csr.json << EOF
{
  "CN": "system:kube-controller-manager",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:kube-controller-manager",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
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

}

Kube Proxy client cert:

{

cat > kube-proxy-csr.json << EOF
{
  "CN": "system:kube-proxy",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:node-proxier",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
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

}

Kube Scheduler client cert:

{

cat > kube-scheduler-csr.json << EOF
{
  "CN": "system:kube-scheduler",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:kube-scheduler",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
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

}

Challenge

Generate the Kubernetes API server certificate.

You can generate the Kubernetes API server certificate like so:

{

cat > kubernetes-csr.json << EOF
{
  "CN": "kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "Kubernetes",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
EOF

cfssl gencert 
  -ca=ca.pem 
  -ca-key=ca-key.pem 
  -config=ca-config.json 
  -hostname=10.32.0.1,172.34.0.0,controller0.mylabserver.com,172.34.0.1,controller1.mylabserver.com,172.34.2.0,kubernetes.mylabserver.com,127.0.0.1,localhost,kubernetes.default 
  -profile=kubernetes 
  kubernetes-csr.json | cfssljson -bare kubernetes

}

Challenge

Generate a Kubernetes service account key pair.

To generate the service account key pair, do the following:

{

cat > service-account-csr.json << EOF
{
  "CN": "service-accounts",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "Kubernetes",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
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

}

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

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