Running the Sample BlueChatter App on Kubernetes

since last month, bluemix has started to support kubernetes (beta), which many people consider the de-facto standard for container orchestration. some of the older and simpler bluemix sample applications use docker-compose. below is a description of how to run those examples on kubernetes.

essentially, the docker-compose file needs to be converted to a kubernetes yaml file. for example, i use the chat application bluechatter . the sample is a node.js application that leverages redis to store session data. the file docker-compose.yml defines the two containers: the ports and links.

in order to create the kubernetes configuration file, i’ve tried an open source project kompose (kubernetes + compose) . when you run it, four files are created, two for the deployments and two for the services. for a quick introduction to these terms, watch this video . i’ve merged everything into one file.

there were only two things i had to manually change in the file.

1. i had to enter the name of my docker image, e.g. ‘registry.ng.bluemix.net/nheidloff/bluechatter_web’

2. in order to expose the web application via a public ip address, i defined a public port for the ‘web’ service via nodeport .

here is a screenshot of the kubernetes dashboard.

here is the kubernetes file ‘bluechatter.yaml’.

apiversion: extensions/v1beta1
kind: deployment
metadata:  
  name: redis
spec:
  replicas: 1  
  template:
    metadata:      
      labels:
        bluechatter: redis
    spec:
      containers:
      - image: redis
        name: redis        
      restartpolicy: always
---
apiversion: v1
kind: service
metadata:  
  labels:
    bluechatter: redis
  name: redis
spec:
  clusterip: none
  ports:
  - name: headless
    port: 55555
    targetport: 0
  selector:
    bluechatter: redis
---
apiversion: extensions/v1beta1
kind: deployment
metadata:  
  name: web
spec:
  replicas: 1
  template:
    metadata:
      labels:
        bluechatter: web
    spec:
      containers:
      - name: web
        image: registry.ng.bluemix.net/nheidloff/bluechatter_web
        ports:
        - containerport: 80
        - containerport: 8080
      restartpolicy: always
---
apiversion: v1
kind: service
metadata:
  labels:
    bluechatter: web
  name: web
spec:
  type: nodeport
  ports:
  - name: "80"
    port: 80
    nodeport: 30072  
  selector:
    bluechatter: web

run these commands to create and configure a cluster.

$ bx cs cluster-create --name my_cluster
$ bx cs workers my_cluster # wait and repeat until state is 'deployed'
$ bx cs cluster-config my_cluster # copy and paste the 'export ...' line

run these commands to build the containers of the sample .

$ git clone https://github.com/ibm-bluemix/bluechatter.git
$ cd bluechatter
$ docker-compose build
$ docker tag bluechatter_web registry.ng.bluemix.net/nheidloff/bluechatter_web
$ docker push registry.ng.bluemix.net/nheidloff/bluechatter_web

run these commands to deploy the sample application.

$ kubectl create -f bluechatter.yaml
$ bx cs workers my_cluster # to get the public ip
$ kubectl describe service web # to get the port (nodeport)