In this blog post we learn how to provision a Kubernetes cluster using Google Kubernetes Engine and deploy and manage Docker containers using kubectl.
Setup
Make sure the following APIs are enabled in Cloud Platform Console
- Kubernetes Engine API
- Container Registry API
On the Navigation menu, click APIs & services.
Scroll down and confirm that your APIs are enabled.
If an API is missing, click ENABLE APIS AND SERVICES at the top, search for the API by name, and enable it for your project.
Activate Google Cloud Shell
In GCP console, on the top right toolbar, click the Open Cloud Shell button.
In the dialog box that opens, click Start Cloud Shell:
It takes a few moments to provision and connect to the environment. When you are connected, you are already authenticated, and the project is set to your PROJECT_ID. For example:
List the active account name
gcloud auth list
List the project ID
gcloud config list project
Start a Kubernetes cluster
Define your zone as a project default zone
This way you do not need to specify --zone parameter in gcloud commands.
gcloud config set compute/zone us-central1-a
In Cloud Shell, run the following command to start a Kubernetes cluster called bootcamp that runs 5 nodes.
gcloud container clusters create bootcamp --num-nodes 5 --scopes "https://www.googleapis.com/auth/projecthosting,storage-rw"
The scopes argument provides access to project hosting and Google Cloud Storage APIs that you'll use later.
It takes several minutes to create a cluster as Kubernetes Engine provisions virtual machines for you. It spins up one or more master nodes and multiple configured worker nodes. This is one of the advantages of a managed service.
Check your installed version of Kubernetes
kubectl version
The gcloud container clusters create command automatically authenticated kubectl for you.
Find out more about the cluster
kubectl cluster-info
Bash Completion (Optional)
Kubernetes comes with auto-completion. You can use the kubectl completion command and the built-in source command to set this up.
Run this command.
source <(kubectl completion bash)
Press Tab to display a list of available commands.
Try the following examples:
kubectl <TAB><TAB>
You can also complete a partial command.
kubectl co<TAB><TAB>
This feature makes using kubectl even easier.
Run and deploy a container
Get started with Kubernetes
Use kubectl run to launch a single instance of the nginx container
kubectl run nginx --image=nginx:1.10.0
In Kubernetes, all containers run in pods. And in this command, Kubernetes created what is called a deployment behind the scenes, and runs a single pod with the nginx container in it. A deployment keeps a given number of pods up and running even when the nodes they run on fail. In this case, you run the default number of pods, which is 1.
View the pod running the nginx container
kubectl get pods
Expose the nginx container outside Kubernetes
kubectl expose deployment nginx --port 80 --type LoadBalancer
Kubernetes created a service and an external load balancer with a public IP address attached to it (you will learn about services later). The IP address remains the same for the life of the service. Any client who hits that public IP address (for example an end user or another container) is routed to pods behind the service. In this case, that would be the nginx pod.
View the new service
kubectl get services
You'll see an external IP that you can use to test and contact the nginx container remotely.
It may take a few seconds before the ExternalIP field is populated for your service. This is normal—just re-run the kubectl get services command every few seconds until the field is populated.
Scale up the number of backend applications (pods) running on your service
kubectl scale deployment nginx --replicas 3
This is useful when you want to increase workload for a web application that is becoming more popular.
Get the pods one more time to confirm that Kubernetes has updated the number of pods
kubectl get pods
Use the kubectl get services command again to confirm that your external IP address has not changed
kubectl get services
Use the external IP address with the curl command to test your demo application
curl http://<External IP>:80
Kubernetes supports an easy-to-use workflow out of the box using the kubectl run, expose, and scale commands.
Clean Up
Clean up nginx
kubectl delete deployment nginx
kubectl delete service nginx
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