Dev Days Lisbon 2018 Kubernetes workshop

Held here.

Prerequisites

Make sure you have the following installed on your local machine:

• Docker: For building your container images and pushing them to a docker registry of choice.
• Minikube: For running a local 1-node K8s cluster
• Kubectl: For communicating with different k8s clusters

Minikube setup

Boot minikube.

minikube start

You can check status of your minikube cluster by running,

minikube status

Build a Hello World PHP docker image

This is just to get the hang of deploying a small application using k8s. Substitute <namespace> with your Dockerhub namespace in all commands.

cd k8s/minikube-hello-world

docker build <namespace>/php-k8s:v1 .

Push your image to Dockerhub public registry. Make sure you have logged in to your Dockerhub account using docker login.

docker push <namespace>/php-k8s:v1

Deploy your first application to K8s

Pods are the basic units of a K8s cluster.

kubectl get pods

You should get "no resources found".

Deploy the image we previously created

kubectl run hello-world --image=<namespace>/php-k8s:v1 --port=8080

Expose your pods to outside world using services.

kubectl expose deployment hello-world --type=LoadBalancer

Open service in browser.

minikube service hello-world

Deploy the same application using YAML manifests

Apply the deployment.

cd k8s/minikube-hello-world
kubectl apply -f deployment.yml 

Apply the service.

kubectl apply -f service.yml 

Get the name of a pod

First, get the list of pods.

kubectl get po

NAME                                          READY     STATUS    RESTARTS   AGE
drupal-56f6c47f76-l8fkn                       1/1       Running   0          1h
hello-world-6686ff999b-wh2tr                  1/1       Running   0          2h
mysql-7fd9c8467d-22zg4                        1/1       Running   0          1h
php-hello-world-deployment-78dc8f54cc-9jkf8   1/1       Running   0          2h
php-hello-world-deployment-78dc8f54cc-wkdtc   1/1       Running   0          2h
php-hello-world-deployment-78dc8f54cc-zzgnt   1/1       Running   0          2h

The first column is the pod name. Substitute <pod-name> with the pod name you want in upcoming commands.

Delete a pod

We have set a replication factor of 3 for the hello-world PHP pod. Let's try to delete one of the pods.

kubectl delete pods <pod-name>

K8s will automatically re-provision a new pod to maintain the replication factor of 3.

Deploy a new image

cd k8s/minikube-hello-world

Change the index.php to add some text.

Rebuild the new image.

docker build -t <namespace>/php-k8s:v2

Push to Docker Registry.

docker push <namespace>/php-k8s:v2

Open deployment.yml and edit the image to point to new version,

    spec:
      containers:
      - name: php-hello-world
        image: <namespace>/php-k8s:v2
        ports:
        - containerPort: 8080

And apply the deployment again.

kubectl apply -f deployment.yml 

Verify that your change is reflected by visiting the service.

minikube service php-hello-world-svc # this is the service name you have in service.yml file

Deploy Drupal 8 on Minikube

Drupal and MySQL have persistent volumes. K8s is a container based system, so no data is persisted and pods are ephermeral, like containers. We use a new set of resources called volumes and volume claims to persist app data between deployments.

Create persistent volumes

cd k8s/minikube-compact
kubectl apply -f local-volumes.yml

Get the volumes in system using,

kubectl get pv

Create a MySQL related secret(password)

Instead of openly adding the MySQL password, we create a new K8s construct called secret.

kubectl create secret generic mysql --from-literal=password=<your-mysql-password>

Apply a MySQL deployment

This will create the pods, services and volume claims associated with the database.

kubectl apply -f mysql-deployment.yml

Check the persistent volume claim by running,

kubectl get pvc

Create Drupal image

Go to the top level directory in the repo you cloned and run,

docker build -t <namespace>/drupal-8:plain-1

Visit the Dockerfile at the top level directory to see how the image is built, and to make any needed changes.

Push to registry.

docker push <namespace>/drupal-8:plain-1

Apply a Drupal deployment

cd k8s/minikube-compact

Change the image if needed in the deployment manifest,

  template:
    metadata:
      labels:
        app: drupal
    spec:
      containers:
        - image: <namespace>/drupal-8:plain-1
          name: drupal
          env:

Apply deployment.

kubectl apply -f drupal-deployment.yml

Get logs of a pod

To tail the pod logs,

kubectl logs -f <pod-name>

Describe a pod

to show the status, history of state and other metadata associated with a pod.

kubectl describe po <pod-name>

Using drush inside a pod

To ssh into your pod,

kubectl exec -it <pod-name> -- /bin/bash

./vendor/bin/drush si --db-url="mysql://root:<password-you-gave-when-creating-secret>/drupal8" -y

Make sure you copy the admin password drush site-install generates for you.

Exit shell and run Drupal.

minikube service drupal # the service name you gave in drupal-deployment.yml

Deploy a change to Drupal in Minikube

Let's make a change on our codebase, like download the devel module.

Go to the top level directory, and run

composer require drupal/devel

Build a new version of docker image,

docker build -t <namespace>/drupal-8:plain-2

Push to registry,

docker push <namespace>/drupal-8:plain-2

Change the image in deployment manifest and apply new deployment, as mentioned in the "Apply a Drupal deployment" section above.

Confirm that devel module is present in the modules/extend page.

minikube service drupal

TODO

• Create K8s cluster on a cloud provider
• Deploy Drupal in a K8s cluster running in the cloud
• Point to a domain/create ingress

Contact

Please mail to "lakshmi@lakshminp.com" with "k8s workshop" in the subject.