Continuous Delivery Pipeline for Scala Application on Kubernetes

Reading Time: 6 Minutes

by  | December 22, 2017 

Overview

Running Containers at any real-world scale requires container orchestration, and scheduling platform like Docker Swarm, Apache Mesos, AWS ECS but the most popular out of it is Kubernetes. Kubernetes is an open source system for automating deployment and management of containerised applications. 

Continuous delivery is a branch of continuous integration. It concentrates on automating the software delivery process so that teams can quickly and confidently deploy their code to production at any point.

Read More About Continuous Delivery

In this post, We’ll share the process how you can Develop and Deploy Microservices based PHP Laravel Application on the Container Environment -  Docker and Kubernetes and adopt DevOps in existing PHP Applications.

Prerequisites For Deploying Laravel Application on Kubernetes

To follow this guide you need -

• Kubernetes

• Kubectl

• Scala Application Source Code

• Dockerfile

• Container-Registry

• Kubernetes

It is an open source platform that automates container operations, and Minikube is best for testing Kubernetes.

• Kubectl

Kubectl is command line interface to manage Kubernetes cluster either remotely or locally. To configure kubectl on your machine follow this link.

• Shared Persistent Storage

Shared Persistent Storage is permanent storage that we can attach to the Kubernetes container so that we don`t lose our data even when container dies. We will be using GlusterFS as the persistent data store for Kubernetes container applications.

• Scala Application Source Code

Scala Application Source Code is source code that we want to run inside a Kubernetes container.

• DockerFile

Dockerfile contains a bunch of commands to build PHP Laravel application.

• Container Registry

The Registry is an online image store for container images.

Below mentioned options are few most popular registries.

• Private Docker Hub

• AWS ECR

• Docker Store

• Google Container Registry

Writing a Dockerfile

At the time of writing this blog, I haven`t got any official image of Scala sbt so I decided to build a base image for Scala sbt. In this image, we are using OpenJDK 8 as a development environment and Scala sbt 0.13.

FROM openjdk: 8
RUN apt - get update\ && apt - get install apt - transport - https - y
RUN echo "deb https://dl.bintray.com/sbt/debian /" | tee - a / etc / apt / sources.list.d / sbt.list\ && apt - key adv--keyserver hkp: //keyserver.ubuntu.com:80 --recv 2EE0EA64E40A89B84B2DF73499E82A75642AC823 \
 && apt - get update\ && apt - get install sbt - y\ && rm - rf /
 var / lib / apt / lists /*

You May also Love to Read Deploying Microservices Based Java Application on Docker & Kubernetes

Building Scala Base Image

The Below mentioned command will build your scala base container image.

$ docker build -t scala-sbt:0.13

Dockerfile (Application)

As Scala sbt don't have any official image of Docker container so we will be using above created image of Scala sbt as a base image for Scala applications.

FROM scala - sbt: 0.13

MAINTAINER Don

# Creating Home Directory in container
RUN mkdir - p / usr / src / app

# Setting Home Directory
WORKDIR / usr / src / app

# Copying src code to Container
COPY. / usr / src / app

# Compiling Scala Code
RUN sbt compile

# Exposing Port
EXPOSE 3000

# Running Scala Application
CMD["sbt", "run"]

Building Scala Application Image

The below-mentioned command will build your application container image.

$ docker build -t <name application="" of="" scala="" your="">:<version application="" of="">

Publishing Scala Application Container Image

Now we publish our Scala application container image on Private Docker Registry.

• Login to Container Registry

$ docker login < dns link of private container registry >
 Username: xxxx
Password: xxxxx

• Retag Container Images

$ docker tag <name application="" of="" your="">:<version application="" of="" your=""> <privater name="" registry="">/<name of="" repository="" your="">:<version application="" of="" your="">

• Push Application container Images

$ docker push < privater registry name > /<name of="" repository="" your="">:<version application="" of="" your="">

apiVersion: extensions / v1beta1
kind: Deployment
metadata:
 name: < name of application >
 namespace: < namespace of Kubernetes >
 spec:
 replicas: < number of application pods >
 template:
 metadata:
 labels:
 k8s - app: < name of application >
 spec:
 containers:
 -name: < name of application >
 image: < image name > : < version tag >
 imagePullPolicy: "IfNotPresent"
ports:
 -containerPort: 9000

apiVersion: v1
kind: Service
metadata:
 labels:
 k8s - app: < name of application >
 name: < name of application >
 namespace: < namespace of Kubernetes >
 spec:
 type: NodePort
ports:
 -port: 9000
selector:
 k8s - app: < name of application >
 
 

$ kubectl create -f <name application="" of="">.deployment.yml
$ kubectl create -f <name application="" of="">.service.yml

$ kubectl get po --namespace=<namespace kubernetes="" of=""> | grep <application name="">

$ kubectl get svc--namespace = < namespace of kubernetes > | grep < application name >