The goal of this codelab is for you to turn your code (a simple Hello World node.js app here) into a replicated application running on Kubernetes. We will show you how to take code that you have developed on your machine, turn it into a Docker container image, and then run that image on Google Kubernetes Engine.
Here's a diagram of the various parts in play in this codelab to help you understand how pieces fit with one another. Use this as a reference as we progress through the codelab; it should all make sense by the time we get to the end (but feel free to ignore this for now).
Kubernetes is an open source project (available on kubernetes.io) which can run on many different environments, from laptops to high-availability multi-node clusters, from public clouds to on-premise deployments, from virtual machines to bare metal.
For the purpose of this codelab, using a managed environment such as Google Kubernetes Engine (a Google-hosted version of Kubernetes) will allow you to focus more on experiencing Kubernetes rather than setting up the underlying infrastructure.
If you are interested in running Kubernetes on your local machine, say a development laptop, you should probably look into Minikube: http://kubernetes.io/docs/getting-started-guides/minikube/. This offers a simple setup of a single node Kubernetes cluster for development and testing purposes. You can use Minikube to go through this codelab if you wish.
Codelab-at-a-conference setup
If you see a "request account button" at the top of the main Codelabs window, click it to obtain a temporary account. Otherwise ask one of the staff for a coupon with username/password.
These temporary accounts have existing projects that are set up with billing so that there are no costs associated for you with running this codelab.
Note that all these accounts will be disabled soon after the codelab is over.
Use these credentials to log into the machine or to open a new Google Cloud Console window https://console.cloud.google.com/. Accept the new account Terms of Service and any updates to Terms of Service.
Here's what you should see once logged in:
When presented with this console landing page, please select the only project available. Alternatively, from the console home page, click on "Select a Project" :
Google Cloud Shell
While Google Cloud and Kubernetes can be operated remotely from your laptop, in this codelab we will be using Google Cloud Shell, a command line environment running in the Cloud.
This Debian-based virtual machine is loaded with all the development tools you'll need. It offers a persistent 5GB home directory, and runs on the Google Cloud, greatly enhancing network performance and authentication. This means that all you will need for this codelab is a browser (yes, it works on a Chromebook).
To activate Google Cloud Shell, from the developer console simply click the button on the top right-hand side (it should only take a few moments to provision and connect to the environment):
Click the "Start Cloud Shell" button:
Once connected to the cloud shell, you should see that you are already authenticated and that the project is already set to your PROJECT_ID :
gcloud auth list
Command output
Credentialed accounts: - <myaccount>@<mydomain>.com (active)
gcloud config list project
Command output
[core] project = <PROJECT_ID>
Cloud Shell also sets some environment variables by default which may be useful as you run future commands.
echo $GOOGLE_CLOUD_PROJECT
Command output
<PROJECT_ID>
If for some reason the project is not set, simply issue the following command :
gcloud config set project <PROJECT_ID>
Looking for your PROJECT_ID? Check out what ID you used in the setup steps or look it up in the console dashboard:
IMPORTANT: Finally, set the default zone and project configuration:
gcloud config set compute/zone us-central1-f
You can choose a variety of different zones. Learn more in the Regions & Zones documentation.
The first step is to write the application that we want to deploy to Google Kubernetes Engine. Here is a simple Node.js server (use Cloud Shell):
vi server.js
With this content:
var http = require('http');
var handleRequest = function(request, response) {
response.writeHead(200);
response.end("Hello World!");
}
var www = http.createServer(handleRequest);
www.listen(8080);From Cloud Shell simply exit the editor and save the server.js file. Since CloudShell has the node executable installed we can now run this simple command (the command produces no output) :
node server.js
and use the built-in Web preview feature of CloudShell to open a new browser tab and proxy a request to the instance you just started on port 8080.
Now, more importantly, let's package this application in a Docker container.
Before we continue, stop the running node server by pressing Ctrl-C in CloudShell.
Next, create a Dockerfile which describes the image that you want to build. Docker container images can extend from other existing images so for this image, we'll extend from an existing Node image.
vi Dockerfile
With this content :
FROM node:12.12.0
EXPOSE 8080
COPY server.js .
CMD node server.jsThis "recipe" for the Docker image will start from the node image found on the Docker hub, expose port 8080, copy our server.js file to the image and start the node server as we previously did manually.
Save this Dockerfile and build this image by running the following command :
docker build -t gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v1 .
Once this completes (it'll take some time to download and extract everything) you can test the image locally with the following command which will run a Docker container as a daemon on port 8080 from our newly-created container image:
docker run -d -p 8080:8080 gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v1
This is the console output you should see something similar to this:
325301e6b2bffd1d0049c621866831316d653c0b25a496d04ce0ec6854cb7998
And again take advantage of the Web preview feature of CloudShell :
Or use curl or wget from your CloudShell prompt if you'd like :
curl http://localhost:8080
This is the console output you should see :
Hello World!
Let's now stop the running container. In this example, our app was running as Docker process 2c66d0efcbd4 :
docker ps
This is the console output you should see :
CONTAINER ID IMAGE COMMAND 2c66d0efcbd4 gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v1 "/bin/sh -c 'node
Stop the running container using the ID provide above :
docker stop 2c66d0efcbd4
This is the console output you should see :
2c66d0efcbd4
Now that the image works as intended we can push it to the Google Container Registry, a private repository for your Docker images accessible from your Google Cloud projects. Let's first enable the registry. For that use the top-level search box in the console to look for "registry", select "Container Registry" and enable the feature :
You can now push your container image to this cloud private registry :
docker -- push gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v1
This initial push may take a few minutes to complete:
The push refers to a repository [gcr.io/qwiklabs-gcp-6h281a111f098/hello-node] ba6ca48af64e: Pushed 381c97ba7dc3: Pushed 604c78617f34: Pushed fa18e5ffd316: Pushed 0a5e2b2ddeaa: Pushed 53c779688d06: Pushed 60a0858edcd5: Pushed b6ca02dfe5e6: Pushed v1: digest: sha256:8a9349a355c8e06a48a1e8906652b9259bba6d594097f115060acca8e3e941a2 size: 2002
At this point you should be able to see the container image listed in the console: Tools > Container Registry. At this point we now have a project-wide Docker image available which Kubernetes can access and orchestrate as we'll see in a few minutes.
Ok, you are now ready to create your Kubernetes cluster but before that, navigate to the Google Kubernetes Engine section of the web console and wait for the system to initialize (it should only take a few seconds).
A cluster consists of a Kubernetes master API server hosted by Google and a set of worker nodes. The worker nodes are Compute Engine virtual machines.
First, make sure you have set your project using gcloud :
gcloud config set project PROJECT_IDLet's use the gcloud CLI from your CloudShell session to create a cluster with two n1-standard-1 nodes (this will take a few minutes to complete):
gcloud container clusters create hello-world \
--num-nodes 2 \
--machine-type n1-standard-1 \
--zone us-central1-f
This is the console output you should see :
Creating cluster hello-world...done. Created [https://container.googleapis.com/v1/projects/PROJECT_ID/zones/us-central1-f/clusters/hello-world]. kubeconfig entry generated for hello-world. NAME LOCATION MASTER_VERSION MASTER_IP MACHINE_TYPE NUM_NODES STATUS hello-world us-central1-f 1.13.10-gke.0 35.232.69.3 n1-standard-1 2 RUNNING
You should now have a fully-functioning Kubernetes cluster powered by Google Kubernetes Engine:
It's now time to deploy your own containerized application to the Kubernetes cluster!
From now on we'll use the kubectl command line (already set up in your Cloud Shell environment).
A Kubernetes pod is a group of containers, tied together for the purposes of administration and networking. It can contain a single container or multiple. Here we'll simply use one container built with your Node.js image stored in our private container registry. It will serve content on port 8080.
A Kubernetes Deployment checks on the health of your Pod and restarts the Pod's Container if it terminates. Deployments are the recommended way to manage the creation and scaling of Pods.
So let's now create a pod with the kubectl create deployment command to create a Deployment that manages a Pod. The Pod runs a Container based on the provided Docker image.:
kubectl create deployment hello-node \
--image=gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v1 \
--port=8080
This is the console output you should see :
deployment.apps/hello-node created
As you can see, we've created a deployment object. Deployments are the recommended way to create and scale pods. Here, a new deployment manages a single pod replica running the hello-node:v1 image.
To view the deployment we just created, simply run :
kubectl get deployments
This is the console output you should see :
NAME READY UP-TO-DATE AVAILABLE AGE hello-node 1/1 1 1 2m
To view the pod created by the deployment, run this command :
kubectl get pods
This is the console output you should see :
NAME READY STATUS RESTARTS AGE hello-node-714049816-ztzrb 1/1 Running 0 6m
Now is a good time to run through some interesting kubectl commands (none of these will change the state of the cluster, full documentation is available here):
kubectl cluster-infokubectl config viewAnd for troubleshooting :
kubectl get eventskubectl logs <pod-name>At this point you should have our container running under the control of Kubernetes but we still have to make it accessible to the outside world.
By default, the pod is only accessible by its internal IP within the cluster. In order to make the hello-node container accessible from outside the Kubernetes virtual network, you have to expose the pod as a Kubernetes service.
From CloudShell we can expose the pod to the public internet with the kubectl expose command combined with the --type="LoadBalancer" flag. This flag is required for the creation of an externally accessible IP :
kubectl expose deployment hello-node --type=LoadBalancer --port=8080
This is the console output you should see :
service/hello-node exposed
The flag used in this command specifies that we'll be using the load-balancer provided by the underlying infrastructure (in this case the Compute Engine load balancer). Note that we expose the deployment, and not the pod directly. This will cause the resulting service to load balance traffic across all pods managed by the deployment (in this case only 1 pod, but we will add more replicas later).
The Kubernetes master creates the load balancer and related Compute Engine forwarding rules, target pools, and firewall rules to make the service fully accessible from outside of Google Cloud Platform.
To find the publicly-accessible IP address of the service, simply request kubectl to list all the cluster services:
kubectl get services
This is the console output you should see :
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE hello-node LoadBalancer 10.3.29.107 104.154.90.147 8080:32036/TCP 3m6s kubernetes ClusterIP 10.3.240.1 <none> 443/TCP 8m
Note there are 2 IP addresses listed for our service, both serving port 8080. One is the internal IP that is only visible inside your cloud virtual network; the other is the external load-balanced IP. In this example, the external IP address is 104.154.90.147.
You should now be able to reach the service by pointing your browser to this address: http://<EXTERNAL_IP>:8080
At this point we've gained at least several features from moving to containers and Kubernetes - we do not need to specify on which host to run our workload and we also benefit from service monitoring and restart. Let's see what else we can gain from our new Kubernetes infrastructure.
One of the powerful features offered by Kubernetes is how easy it is to scale your application. Suppose you suddenly need more capacity for your application; you can simply tell the replication controller to manage a new number of replicas for your pod:
kubectl scale deployment hello-node --replicas=4
This is the console output you should see :
deployment.extensions/hello-node scaled
At this point you can request a description of the updated deployment :
kubectl get deployment
This is the console output you should see :
NAME READY UP-TO-DATE AVAILABLE AGE hello-node 4/4 4 4 12m
You can also list the all pods :
kubectl get pods
This is the console output you should see :
NAME READY STATUS RESTARTS AGE hello-node-714049816-g4azy 1/1 Running 0 1m hello-node-714049816-rk0u6 1/1 Running 0 1m hello-node-714049816-sh812 1/1 Running 0 1m hello-node-714049816-ztzrb 1/1 Running 0 16m
Note the declarative approach here - rather than starting or stopping new instances you declare how many instances should be running at all time. Kubernetes reconciliation loops simply make sure the reality matches what you requested and take action if needed.
Here's a diagram summarizing the state of our Kubernetes cluster:
At some point the application that you've deployed to production will require bug fixes or additional features. Kubernetes is here to help you deploy a new version to production without impacting your users.
First, let's modify the application. From CloudShell, edit server.js and update the response message:
response.end("Hello Kubernetes World!");
We can now build and publish a new container image to the registry with an incremented tag (v2 in this case):
docker build -t gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v2 . docker -- push gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v2
We're now ready for Kubernetes to smoothly update our replication controller to the new version of the application. In order to change the image label for our running container, we will need to edit the existing hello-node deployment and change the image from gcr.io/PROJECT_ID/hello-node:v1 to gcr.io/PROJECT_ID/hello-node:v2.
To do this, we will use the kubectl set image command. This will trigger a new deployment rollout with the new updated image.
kubectl set image deployment.apps/hello-node \
hello-node=gcr.io/$GOOGLE_CLOUD_PROJECT/hello-node:v2To track progress of the rollout, you can use this command :
kubectl rollout status deployment hello-nodeThis is the console output you should see :
Waiting for deployment "hello-node" rollout to finish: 3 of 4 updated replicas are available...
deployment "hello-node" successfully rolled outWhile this is happening, the users of the services should not see any interruption. After a little while they will start accessing the new version of your application. You can find more details on rolling updates in this documentation.
Hopefully with these deployment, scaling and update features you'll agree that once you've setup your environment (your GKE cluster here), Kubernetes is here to help you focus on the application rather than the infrastructure.
Google Kubernetes Engine comes with rich admin features built right into the web console. This includes an explorer for workloads, for services and load-balancing, for secrets configuration, and for persistent volume claims.
There is no additional setup required to access all of these features.
You can also leverage the powerful set of Stackdriver logging and monitoring features to observe your workloads.