Instance Groups

Setting up a single VM

gcloud compute instances create nginx \
  	--image-family gci-stable \
    --image-project google-containers \
    --machine-type n1-standard-1

Login into the nginx VM

gcloud compute ssh nginx

Start the Kubernetes kubelet; which will manage our containers:

sudo systemctl enable kubelet
sudo systemctl start kubelet

Create a Pod manifest to run the nginx container under the Kubernetes kubelet.

cat > nginx.yaml << EOF
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  hostNetwork: true
  containers:
    - name: nginx
      image: nginx:1.10.1
EOF

Move the nginx pod manifest into place:

sudo mv nginx.yaml /etc/kubernetes/manifests/

Allow HTTP traffic

sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT

Test the nginx service

Exit out of the nginx VM and run the following commands to test the nginx instance

gcloud compute firewall-rules create nginx --allow tcp:80

NGINX_PUBLIC_ADDRESS=$(gcloud compute instances describe nginx \
  --format 'value(networkInterfaces[0].accessConfigs[0].natIP)')

curl http://${NGINX_PUBLIC_ADDRESS}

Automate VM creation using cloud-init

cat > cloud-init << EOF
#cloud-config

write_files:
  - path: etc/kubernetes/manifests/nginx.yaml
    permissions: 0644
    owner: root
    content: |
      apiVersion: v1
      kind: Pod
      metadata:
        name: nginx
      spec:
        hostNetwork: true
        containers:
          - name: nginx
            image: nginx:1.10.1
runcmd:
  - systemctl daemon-reload
  - systemctl start kubelet
  - iptables -A INPUT -p tcp --dport 80 -j ACCEPT
  - iptables-save
EOF

gcloud compute instances create nginx-cloud-init \
  --image-family gci-stable \
  --image-project google-containers \
  --machine-type n1-standard-1 \
  --metadata-from-file user-data=cloud-init

Testing the nginx-cloud-init VM:

NGINX_CI_PUBLIC_ADDRESS=$(gcloud compute instances describe nginx-cloud-init \
  --format 'value(networkInterfaces[0].accessConfigs[0].natIP)')

$ curl http://${NGINX_CI_PUBLIC_ADDRESS}

Cloud-init is greate for automating the creation of a single VM, but what if you need say 100 VMs just like this one?

Creating multiple VMs using instance-templates

$ gcloud compute instance-templates create nginx-instance-template \
  --image-family gci-stable \
  --image-project google-containers \
  --machine-type n1-standard-1 \
  --metadata-from-file user-data=cloud-init

$ gcloud compute instance-groups managed create nginx-instance-group \
  --base-instance-name nginx \
  --size 3 \
  --template nginx-instance-template

NAME                  LOCATION    SCOPE  BASE_INSTANCE_NAME  SIZE  TARGET_SIZE  INSTANCE_TEMPLATE        AUTOSCALED
nginx-instance-group  us-west1-b  zone   nginx               0     3            nginx-instance-template  no

$ gcloud compute instances list

NAME        ZONE        MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
nginx-7dp9  us-west1-b  n1-standard-1               10.240.0.2   104.199.112.124  RUNNING
nginx-sipu  us-west1-b  n1-standard-1               10.240.0.4   104.199.114.154  RUNNING
nginx-zs7v  us-west1-b  n1-standard-1               10.240.0.3   104.199.124.134  RUNNING

Manually scaling an instance group

$ gcloud compute instance-groups managed resize nginx-instance-group --size 5

$ gcloud compute instances list

NAME        ZONE        MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
nginx-7dp9  us-west1-b  n1-standard-1               10.240.0.2   104.199.112.124  RUNNING
nginx-o68k  us-west1-b  n1-standard-1               10.240.0.6   104.199.114.46   RUNNING
nginx-sipu  us-west1-b  n1-standard-1               10.240.0.4   104.199.114.154  RUNNING
nginx-sz84  us-west1-b  n1-standard-1               10.240.0.5   104.199.116.59   RUNNING
nginx-zs7v  us-west1-b  n1-standard-1               10.240.0.3   104.199.124.134  RUNNING

Scaling back down

$ gcloud compute instance-groups managed resize nginx-instance-group --size 1

$ gcloud compute instances list

NAME        ZONE        MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
nginx-zs7v  us-west1-b  n1-standard-1               10.240.0.3   104.199.124.134  RUNNING

Autoscaling

Start with the instance group size set to 1:

gcloud compute instance-groups managed resize nginx-instance-group --size 1

Set an autoscaling policy:

gcloud compute instance-groups managed set-autoscaling nginx-instance-group \
  --max-num-replicas 20 \
  --target-cpu-utilization 0.05 \
  --cool-down-period 90

Notice the nginx-instance-group has autoscale enabled.

$ gcloud compute instance-groups managed list

NAME                  ZONE        BASE_INSTANCE_NAME  SIZE  TARGET_SIZE  INSTANCE_TEMPLATE        AUTOSCALED
nginx-instance-group  us-west1-b  nginx               1     2            nginx-instance-template  yes

The default min size of an instance group is 2. Notice how the instance group has been autoscaled to meet the target size of 2:

$ gcloud compute instances list

NAME        ZONE        MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
nginx-o3xl  us-west1-b  n1-standard-1               10.240.0.2   104.199.114.154  RUNNING
nginx-zs7v  us-west1-b  n1-standard-1               10.240.0.3   104.199.124.134  RUNNING

Trigger an autoscaling event

Install a load tester:

https://github.com/rakyll/hey

go get -u github.com/rakyll/hey

Push some load to one of the nginx machines

Set the public IP address:

NGINX_PUBLIC_ADDRESS=$(gcloud compute instances describe nginx-zs7v \
  --format 'value(networkInterfaces[0].accessConfigs[0].natIP)')

Test the connection:

$ curl http://${NGINX_PUBLIC_ADDRESS}

Send load to the nginx instance:

hey -n 2000 http://${NGINX_PUBLIC_ADDRESS}

Notice the number of VMs have scaled to 4 because of the CPU spike caused by the hey command:

gcloud compute instances list

NAME        ZONE        MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP      STATUS
nginx-o3xl  us-west1-b  n1-standard-1               10.240.0.2   104.199.114.154  RUNNING
nginx-ot4b  us-west1-b  n1-standard-1               10.240.0.5   104.199.112.124  RUNNING
nginx-sf9m  us-west1-b  n1-standard-1               10.240.0.4   104.198.109.21   RUNNING
nginx-zs7v  us-west1-b  n1-standard-1               10.240.0.3   104.199.124.134  RUNNING