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“My name is Ammar and this is my personal blog, documenting my journey on the quest to become the best person I can be.”

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بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيم

Provisioning a CA and Generating TLS Certificates (Kubernetes The Hardway)

Lanjutkeunn, Lab part 2 Di lab ini Anda akan menyediakan Infrastruktur PKI menggunakan PKI toolkit, cfssl, kemudian menggunakannya untuk mem-bootstrap Otoritas Sertifikat, dan menghasilkan sertifikat TLS untuk komponen berikut: etcd, kube-apiserver, kube-controller-manager, kube-scheduler, kubelet, dan kube-proxy.

Certificate Authority

In this section you will provision a Certificate Authority that can be used to generate additional TLS certificates.

Generate the CA configuration file, certificate, and private key:

{

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

}

Results:

ca-key.pem
ca.pem

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 Generate the admin client certificate and private key:

{

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

}

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:. 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-0 worker-1 worker-2; do
cat > ${instance}-csr.json <<EOF
{
  "CN": "system:node:${instance}",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "Portland",
      "O": "system:nodes",
      "OU": "Kubernetes The Hard Way",
      "ST": "Oregon"
    }
  ]
}
EOF

EXTERNAL_IP=$(lxc info $(instance) | grep eth0 | head -1 | awk '{print $3}')


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-0-key.pem
worker-0.pem
worker-1-key.pem
worker-1.pem
worker-2-key.pem
worker-2.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": "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

}

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": "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

}

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": "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

}

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_PUBLIC_ADDRESS=10.240.0.62

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=10.32.0.1,10.240.0.88,10.240.0.161,10.240.0.39,${KUBERNETES_PUBLIC_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": "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

}

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-0 worker-1 worker-2; do
  lxc file push ca.pem ${instance}-key.pem ${instance}.pem ${instance}/root/
done

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

for instance in controller-0 controller-1 controller-2; do
  lxc file push ca.pem ca-key.pem kubernetes-key.pem kubernetes.pem \
    service-account-key.pem service-account.pem ${instance}/root/
done

Vervication:

lxc exec controller-0 ls
lxc exec worker-0 ls

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.

Lanjutnye: Generating Kubernetes Configuration Files for Authentication - Part 3

Gaskunnnn

Referensi

Happy, Enjoy Ngoprek ~

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