In this lab you will setup the necessary PKI infrastructure to secure the Kubernetes components. This lab will leverage CloudFlare's PKI toolkit, cfssl, to bootstrap a Certificate Authority and generate TLS certificates.
In this lab you will generate a single set of TLS certificates that can be used to secure the following Kubernetes components:
- etcd
- Kubernetes API Server
- Kubernetes Kubelet
In production you should strongly consider generating individual TLS certificates for each component.
After completing this lab you should have the following TLS keys and certificates:
ca-key.pem
ca.pem
kubernetes-key.pem
kubernetes.pem
This lab requires the cfssl
and cfssljson
binaries. Download them from the cfssl repository.
wget https://pkg.cfssl.org/R1.2/cfssl_darwin-amd64
chmod +x cfssl_darwin-amd64
sudo mv cfssl_darwin-amd64 /usr/local/bin/cfssl
wget https://pkg.cfssl.org/R1.2/cfssljson_darwin-amd64
chmod +x cfssljson_darwin-amd64
sudo mv cfssljson_darwin-amd64 /usr/local/bin/cfssljson
wget https://pkg.cfssl.org/R1.2/cfssl_linux-amd64
chmod +x cfssl_linux-amd64
sudo mv cfssl_linux-amd64 /usr/local/bin/cfssl
wget https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64
chmod +x cfssljson_linux-amd64
sudo mv cfssljson_linux-amd64 /usr/local/bin/cfssljson
echo '{
"signing": {
"default": {
"expiry": "8760h"
},
"profiles": {
"kubernetes": {
"usages": ["signing", "key encipherment", "server auth", "client auth"],
"expiry": "8760h"
}
}
}
}' > ca-config.json
Create the CA CSR:
echo '{
"CN": "Kubernetes",
"key": {
"algo": "rsa",
"size": 2048
},
"names": [
{
"C": "US",
"L": "Portland",
"O": "Kubernetes",
"OU": "CA",
"ST": "Oregon"
}
]
}' > ca-csr.json
Generate the CA certificate and private key:
cfssl gencert -initca ca-csr.json | cfssljson -bare ca
Results:
ca-key.pem
ca.csr
ca.pem
openssl x509 -in ca.pem -text -noout
In this section we will generate a TLS certificate that will be valid for all Kubernetes components. This is being done for ease of use. In production you should strongly consider generating individual TLS certificates for each component.
KUBERNETES_PUBLIC_ADDRESS=$(gcloud compute addresses describe kubernetes \
--format 'value(address)')
KUBERNETES_PUBLIC_ADDRESS=$(aws elb describe-load-balancers \
--load-balancer-name kubernetes | \
jq -r '.LoadBalancerDescriptions[].DNSName')
Create the kubernetes-csr.json
file:
cat > kubernetes-csr.json <<EOF
{
"CN": "kubernetes",
"hosts": [
"worker0",
"worker1",
"worker2",
"ip-10-240-0-20",
"ip-10-240-0-21",
"ip-10-240-0-22",
"10.32.0.1",
"10.240.0.10",
"10.240.0.11",
"10.240.0.12",
"10.240.0.20",
"10.240.0.21",
"10.240.0.22",
"${KUBERNETES_PUBLIC_ADDRESS}",
"127.0.0.1"
],
"key": {
"algo": "rsa",
"size": 2048
},
"names": [
{
"C": "US",
"L": "Portland",
"O": "Kubernetes",
"OU": "Cluster",
"ST": "Oregon"
}
]
}
EOF
Generate the Kubernetes certificate and private key:
cfssl gencert \
-ca=ca.pem \
-ca-key=ca-key.pem \
-config=ca-config.json \
-profile=kubernetes \
kubernetes-csr.json | cfssljson -bare kubernetes
Results:
kubernetes-key.pem
kubernetes.csr
kubernetes.pem
openssl x509 -in kubernetes.pem -text -noout
Set the list of Kubernetes hosts where the certs should be copied to:
KUBERNETES_HOSTS=(controller0 controller1 controller2 worker0 worker1 worker2)
The following command will:
- Copy the TLS certificates and keys to each Kubernetes host using the
gcloud compute copy-files
command.
for host in ${KUBERNETES_HOSTS[*]}; do
gcloud compute copy-files ca.pem kubernetes-key.pem kubernetes.pem ${host}:~/
done
The following command will:
- Extract the public IP address for each Kubernetes host
- Copy the TLS certificates and keys to each Kubernetes host using
scp
for host in ${KUBERNETES_HOSTS[*]}; do
PUBLIC_IP_ADDRESS=$(aws ec2 describe-instances \
--filters "Name=tag:Name,Values=${host}" | \
jq -r '.Reservations[].Instances[].PublicIpAddress')
scp ca.pem kubernetes-key.pem kubernetes.pem \
ubuntu@${PUBLIC_IP_ADDRESS}:~/
done