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Kubernetes Guide

The container can be configured to run in kubernetes pretty easily and you can take advantage of the kubectl exec command to run the pull and push scripts to sync up with github when there are changes. the guide assumes you have a working kubernetes setup and kubectl is working.

The configuration below is an example of how to get quickly running.

Configure the application

In this example we'll deploy an example app to its own namespace for ease of separation. Create the following example-namespace.yml file:

apiVersion: v1
kind: Namespace
metadata:
  name: example

Now create the namespace in kubernetes:

kubectl create -f example-namespace.yml

Create the following example-app.yml, this is the bit that actually creates your container and replication controller which references the docker image and your github credentials.

apiVersion: v1
kind: ReplicationController
metadata:
  namespace: example
  name: example-app
  labels:
    example-component: example-app
spec:
  replicas: 1
  selector:
    example-component: example-app
  template:
    metadata:
      labels:
        example-component: example-app
    spec:
      containers:
      - name: example-app
        image: richarvey/nginx-php-fpm:latest
        imagePullPolicy: Always
        env:
          - name: SSH_KEY
            value: '<YOUR_KEY_HERE>'
          - name: GIT_REPO
            value: '[email protected]:<YOUR_USER>/<YOUR_REPO>.git'
          - name: GIT_EMAIL
            value: '<YOUR_EMAIL>'
          - name: GIT_NAME
            value: '<YOUR_NAME>'
        ports:
        - containerPort: 80

Now run:

kubectl create -f example-app.yml

Using the application

Your container should now be up and running and you can see its details with the following commands:

kubectl get pods --namespace example

# make a note of the pod namespace

kubectl describe pod <pod_name> --namespace example

Create a Service for the application

To help expose the application to the outside world you may want to create a service. The example below isn't the only way to do this as it depends on the exact setup of the kubernetes system you have, for example you may want to use an ELB on AWS or you may be on GKE and use googles http load balancer.

Create the file example-service.yml with the following content:

apiVersion: v1
kind: Service
metadata:
  namespace: example
  name: example-app
spec:
  type: ClusterIP
  ports:
    - protocol: TCP
      name: http
      port: 80
      targetPort: 80
  selector:
    app: example-app

Now run:

kubectl create -f example-service.yml

This will create you a service load balancer and allow you to scale your replication controller in the background underneath a unifying IP address. You can get the details by running:

kubectl describe service example-app --namespace example

Running commands in the container/pod

If you want to push or pull code to the container you can run the following commands:

kubectl get pods --namespace example

# make a note of the pod namespace

# update code in the container
kubectl exec -t <pod_name> /usr/bin/pull --namespace example
# push code back to github
kubectl exec -t <pod_name> /usr/bin/push --namespace example

If you want to drop into the shell run the following:

kubectl exec -it <pod_name> bash --namespace example

Scale your app

You can scale the replication controller with the following command:

kubectl scale --replicas=3 rc/example-app --namespace example