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kubernetes-the-hard-way/docs/04-kubernetes-controller.md

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Bootstrapping an H/A Kubernetes Control Plane

In this lab you will bootstrap a 3 node Kubernetes controller cluster. The following virtual machines will be used:

gcloud compute instances list

NAME         ZONE           MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
controller0  us-central1-f  n1-standard-1               10.240.0.20  XXX.XXX.XXX.XXX  RUNNING
controller1  us-central1-f  n1-standard-1               10.240.0.21  XXX.XXX.XXX.XXX  RUNNING
controller2  us-central1-f  n1-standard-1               10.240.0.22  XXX.XXX.XXX.XXX  RUNNING
etcd0        us-central1-f  n1-standard-1               10.240.0.10  XXX.XXX.XXX.XXX  RUNNING

In this lab you will also create a frontend load balancer with a public IP address for remote access to the API servers and H/A.

Why

The Kubernetes components that make up the control plane include the following components:

  • Kubernetes API Server
  • Kubernetes Scheduler
  • Kubernetes Controller Manager

Each component is being run on the same machines for the following reasons:

  • The Scheduler and Controller Manager are tightly coupled with the API Server
  • Only one Scheduler and Controller Manager can be active at a given time, but it's ok to run multiple at the same time. Each component will elect a leader via the API Server.
  • Running multiple copies of each component is required for H/A
  • Running each component next to the API Server eases configuration.

Provision the Kubernetes Controller Cluster

Run the following commands on controller0, controller1, controller2:

SSH into each machine using the gcloud compute ssh command

Move the TLS certificates in place:

sudo mkdir -p /var/lib/kubernetes

sudo mv ca.pem kubernetes-key.pem kubernetes.pem /var/lib/kubernetes/

Download and install the Kubernetes controller binaries:

wget https://storage.googleapis.com/kubernetes-release/release/v1.3.0/bin/linux/amd64/kube-apiserver
wget https://storage.googleapis.com/kubernetes-release/release/v1.3.0/bin/linux/amd64/kube-controller-manager
wget https://storage.googleapis.com/kubernetes-release/release/v1.3.0/bin/linux/amd64/kube-scheduler
wget https://storage.googleapis.com/kubernetes-release/release/v1.3.0/bin/linux/amd64/kubectl

chmod +x kube-apiserver kube-controller-manager kube-scheduler kubectl

sudo mv kube-apiserver kube-controller-manager kube-scheduler kubectl /usr/bin/

Kubernetes API Server

Setup Authentication and Authorization

Authentication

Token based authentication will be used to limit access to Kubernetes API.

wget https://raw.githubusercontent.com/kelseyhightower/kubernetes-the-hard-way/master/token.csv

cat token.csv

sudo mv token.csv /var/lib/kubernetes/
Authorization

Attribute-Based Access Control (ABAC) will be used to authorize access to the Kubernetes API. In this lab ABAC will be setup using the Kuberentes policy file backend as documented in the Kubernetes authorization guide.

wget https://raw.githubusercontent.com/kelseyhightower/kubernetes-the-hard-way/master/authorization-policy.jsonl

cat authorization-policy.jsonl

sudo mv authorization-policy.jsonl /var/lib/kubernetes/

Create the systemd unit file

Capture the internal IP address:

export INTERNAL_IP=$(curl -s -H "Metadata-Flavor: Google" \
  http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/ip)

Create the systemd unit file:

cat > kube-apiserver.service <<"EOF"
[Unit]
Description=Kubernetes API Server
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
ExecStart=/usr/bin/kube-apiserver \
  --admission-control=NamespaceLifecycle,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota \
  --advertise-address=INTERNAL_IP \
  --allow-privileged=true \
  --apiserver-count=3 \
  --authorization-mode=ABAC \
  --authorization-policy-file=/var/lib/kubernetes/authorization-policy.jsonl \
  --bind-address=0.0.0.0 \
  --enable-swagger-ui=true \
  --etcd-cafile=/var/lib/kubernetes/ca.pem \
  --insecure-bind-address=0.0.0.0 \
  --kubelet-certificate-authority=/var/lib/kubernetes/ca.pem \
  --etcd-servers=https://10.240.0.10:2379,https://10.240.0.11:2379,https://10.240.0.12:2379 \
  --service-account-key-file=/var/lib/kubernetes/kubernetes-key.pem \
  --service-cluster-ip-range=10.32.0.0/24 \
  --service-node-port-range=30000-32767 \
  --tls-cert-file=/var/lib/kubernetes/kubernetes.pem \
  --tls-private-key-file=/var/lib/kubernetes/kubernetes-key.pem \
  --token-auth-file=/var/lib/kubernetes/token.csv \
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

sed -i s/INTERNAL_IP/$INTERNAL_IP/g kube-apiserver.service

sudo mv kube-apiserver.service /etc/systemd/system/

sudo systemctl daemon-reload
sudo systemctl enable kube-apiserver
sudo systemctl start kube-apiserver

sudo systemctl status kube-apiserver --no-pager

Kubernetes Controller Manager

cat > kube-controller-manager.service <<"EOF"
[Unit]
Description=Kubernetes Controller Manager
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
ExecStart=/usr/bin/kube-controller-manager \
  --allocate-node-cidrs=true \
  --cluster-cidr=10.200.0.0/16 \
  --cluster-name=kubernetes \
  --leader-elect=true \
  --master=http://INTERNAL_IP:8080 \
  --root-ca-file=/var/lib/kubernetes/ca.pem \
  --service-account-private-key-file=/var/lib/kubernetes/kubernetes-key.pem \
  --service-cluster-ip-range=10.32.0.0/24 \
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

sed -i s/INTERNAL_IP/$INTERNAL_IP/g kube-controller-manager.service

sudo mv kube-controller-manager.service /etc/systemd/system/

sudo systemctl daemon-reload
sudo systemctl enable kube-controller-manager
sudo systemctl start kube-controller-manager

sudo systemctl status kube-controller-manager --no-pager

Kubernetes Scheduler

cat > kube-scheduler.service <<"EOF"
[Unit]
Description=Kubernetes Scheduler
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
ExecStart=/usr/bin/kube-scheduler \
  --leader-elect=true \
  --master=http://INTERNAL_IP:8080 \
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

sed -i s/INTERNAL_IP/$INTERNAL_IP/g kube-scheduler.service

sudo mv kube-scheduler.service /etc/systemd/system/

sudo systemctl daemon-reload
sudo systemctl enable kube-scheduler
sudo systemctl start kube-scheduler

sudo systemctl status kube-scheduler --no-pager

Verification

kubectl get componentstatuses

NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok                   
scheduler            Healthy   ok                   
etcd-1               Healthy   {"health": "true"}   
etcd-0               Healthy   {"health": "true"}   
etcd-2               Healthy   {"health": "true"}

Remember to run these steps on controller0, controller1, and controller2

Setup Kubernetes API Server Frontend Load Balancer

The virtual machines created in this tutorial will not have permission to complete this section. Run the following commands from the same place used to create the virtual machines for this tutorial.

gcloud compute http-health-checks create kube-apiserver-check \
  --description "Kubernetes API Server Health Check" \
  --port 8080 \
  --request-path /healthz

gcloud compute target-pools create kubernetes-pool \
  --health-check kube-apiserver-check \
  --region us-central1

gcloud compute target-pools add-instances kubernetes-pool \
  --instances controller0,controller1,controller2 \
  --zone us-central1-f

export KUBERNETES_PUBLIC_IP_ADDRESS=$(gcloud compute addresses describe kubernetes \
  --format 'value(address)')

gcloud compute forwarding-rules create kubernetes-rule \
  --address ${KUBERNETES_PUBLIC_IP_ADDRESS} \
  --ports 6443 \
  --target-pool kubernetes-pool