The goal of this tutorial is for you to turn a simple Hello World Node.js app into an application running on Kubernetes. The tutorial shows 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 Minikube. Minikube provides a simple way of running Kubernetes on your local machine for free.
xhyve
driver.Note: If you see the following Homebrew error when you run
brew update
after you update your computer to MacOS 10.13:Error: /usr/local is not writable. You should change the ownership and permissions of /usr/local back to your user account: sudo chown -R $(whoami) /usr/local
You can resolve the issue by reinstalling Homebrew:
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
NodeJS is required to run the sample application.
Install Docker. On OS X, we recommend Docker for Mac.
This tutorial uses Minikube to create a local cluster. This tutorial also assumes you are using Docker for Mac on OS X. If you are on a different platform like Linux, or using VirtualBox instead of Docker for Mac, the instructions to install Minikube may be slightly different. For general Minikube installation instructions, see the Minikube installation guide.
Use curl
to download and install the latest Minikube release:
curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-darwin-amd64 && \
chmod +x minikube && \
sudo mv minikube /usr/local/bin/
Use Homebrew to install the xhyve driver and set its permissions:
brew install docker-machine-driver-xhyve
sudo chown root:wheel $(brew --prefix)/opt/docker-machine-driver-xhyve/bin/docker-machine-driver-xhyve
sudo chmod u+s $(brew --prefix)/opt/docker-machine-driver-xhyve/bin/docker-machine-driver-xhyve
Use Homebrew to download the kubectl
command-line tool, which you can
use to interact with Kubernetes clusters:
brew install kubectl
Determine whether you can access sites like https://cloud.google.com/container-registry/ directly without a proxy, by opening a new terminal and using
curl --proxy "" https://cloud.google.com/container-registry/
Make sure that the Docker daemon is started. You can determine if docker is running by using a command such as:
docker images
If NO proxy is required, start the Minikube cluster:
minikube start --vm-driver=xhyve
If a proxy server is required, use the following method to start Minikube cluster with proxy setting:
minikube start --vm-driver=xhyve --docker-env HTTP_PROXY=http://your-http-proxy-host:your-http-proxy-port --docker-env HTTPS_PROXY=http(s)://your-https-proxy-host:your-https-proxy-port
The --vm-driver=xhyve
flag specifies that you are using Docker for Mac. The
default VM driver is VirtualBox.
Note if minikube start --vm-driver=xhyve
is unsuccessful due to the error:
Error creating machine: Error in driver during machine creation: Could not convert the UUID to MAC address: exit status 1
Then the following may resolve the minikube start --vm-driver=xhyve
issue:
rm -rf ~/.minikube
sudo chown root:wheel $(brew --prefix)/opt/docker-machine-driver-xhyve/bin/docker-machine-driver-xhyve
sudo chmod u+s $(brew --prefix)/opt/docker-machine-driver-xhyve/bin/docker-machine-driver-xhyve
Now set the Minikube context. The context is what determines which cluster
kubectl
is interacting with. You can see all your available contexts in the
~/.kube/config
file.
kubectl config use-context minikube
Verify that kubectl
is configured to communicate with your cluster:
kubectl cluster-info
Open the Kubernetes dashboard in a browser:
minikube dashboard
The next step is to write the application. Save this code in a folder named hellonode
with the filename server.js
:
server.js docs/tutorials
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Run your application:
node server.js
You should be able to see your “Hello World!” message at http://localhost:8080/.
Stop the running Node.js server by pressing Ctrl-C.
The next step is to package your application in a Docker container.
Create a file, also in the hellonode
folder, named Dockerfile
. A Dockerfile describes
the image that you want to build. You can build a Docker container image by extending an
existing image. The image in this tutorial extends an existing Node.js image.
Dockerfile docs/tutorials
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This recipe for the Docker image starts from the official Node.js LTS image
found in the Docker registry, exposes port 8080, copies your server.js
file
to the image and starts the Node.js server.
Because this tutorial uses Minikube, instead of pushing your Docker image to a registry, you can simply build the image using the same Docker host as the Minikube VM, so that the images are automatically present. To do so, make sure you are using the Minikube Docker daemon:
eval $(minikube docker-env)
Note: Later, when you no longer wish to use the Minikube host, you can undo
this change by running eval $(minikube docker-env -u)
.
Build your Docker image, using the Minikube Docker daemon (mind the trailing dot):
docker build -t hello-node:v1 .
Now the Minikube VM can run the image you built.
A Kubernetes Pod is a group of one or more Containers, tied together for the purposes of administration and networking. The Pod in this tutorial has only one Container. 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.
Use the kubectl run
command to create a Deployment that manages a Pod. The
Pod runs a Container based on your hello-node:v1
Docker image. Set the
--image-pull-policy
flag to Never
to always use the local image, rather than
pulling it from your Docker registry (since you haven’t pushed it there):
kubectl run hello-node --image=hello-node:v1 --port=8080 --image-pull-policy=Never
View the Deployment:
kubectl get deployments
Output:
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
hello-node 1 1 1 1 3m
View the Pod:
kubectl get pods
Output:
NAME READY STATUS RESTARTS AGE
hello-node-714049816-ztzrb 1/1 Running 0 6m
View cluster events:
kubectl get events
View the kubectl
configuration:
kubectl config view
For more information about kubectl
commands, see the
kubectl overview.
By default, the Pod is only accessible by its internal IP address within the
Kubernetes cluster. To make the hello-node
Container accessible from outside the
Kubernetes virtual network, you have to expose the Pod as a
Kubernetes Service.
From your development machine, you can expose the Pod to the public internet
using the kubectl expose
command:
kubectl expose deployment hello-node --type=LoadBalancer
View the Service you just created:
kubectl get services
Output:
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-node 10.0.0.71 <pending> 8080/TCP 6m
kubernetes 10.0.0.1 <none> 443/TCP 14d
The --type=LoadBalancer
flag indicates that you want to expose your Service
outside of the cluster. On cloud providers that support load balancers,
an external IP address would be provisioned to access the Service. On Minikube,
the LoadBalancer
type makes the Service accessible through the minikube service
command.
minikube service hello-node
This automatically opens up a browser window using a local IP address that serves your app and shows the “Hello World” message.
Assuming you’ve sent requests to your new web service using the browser or curl, you should now be able to see some logs:
kubectl logs <POD-NAME>
Edit your server.js
file to return a new message:
response.end('Hello World Again!');
Build a new version of your image (mind the trailing dot):
docker build -t hello-node:v2 .
Update the image of your Deployment:
kubectl set image deployment/hello-node hello-node=hello-node:v2
Run your app again to view the new message:
minikube service hello-node
Minikube has a set of built-in addons that can be enabled, disabled and opened in the local Kubernetes environment.
First list the currently supported addons:
minikube addons list
Output:
- storage-provisioner: enabled
- kube-dns: enabled
- registry: disabled
- registry-creds: disabled
- addon-manager: enabled
- dashboard: disabled
- default-storageclass: enabled
- coredns: disabled
- heapster: disabled
- efk: disabled
- ingress: disabled
Minikube must be running for these commands to take effect. To enable heapster
addon, for example:
minikube addons enable heapster
Output:
heapster was successfully enabled
View the Pod and Service you just created:
kubectl get po,svc -n kube-system
Output:
NAME READY STATUS RESTARTS AGE
po/heapster-zbwzv 1/1 Running 0 2m
po/influxdb-grafana-gtht9 2/2 Running 0 2m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
svc/heapster NodePort 10.0.0.52 <none> 80:31655/TCP 2m
svc/monitoring-grafana NodePort 10.0.0.33 <none> 80:30002/TCP 2m
svc/monitoring-influxdb ClusterIP 10.0.0.43 <none> 8083/TCP,8086/TCP 2m
Open the endpoint to interacting with heapster in a browser:
minikube addons open heapster
Output:
Opening kubernetes service kube-system/monitoring-grafana in default browser...
Now you can clean up the resources you created in your cluster:
kubectl delete service hello-node
kubectl delete deployment hello-node
Optionally, force removal of the Docker images created:
docker rmi hello-node:v1 hello-node:v2 -f
Optionally, stop the Minikube VM:
minikube stop
eval $(minikube docker-env -u)
Optionally, delete the Minikube VM:
minikube delete