Overview of Scala Application
Scala is an object-oriented programming language. It provides support to functional programming. It also helps to remove bugs in complex applications. In this article, you get to know about Scala and Scala Applications on Kubernetes. 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.
CI/CD Pipeline is a crucial part of the modern DevOps environment. Click to explore about, Continuous Integration and Continuous Delivery
What are the basics terminology for Scala Application?
To follow this guide you need -
It is an open-source platform that automates container operations, and Minikube is best for testing Kubernetes.
Kubectl is a 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
It's source code will be run inside a Kubernetes container.
Dockerfile contains a bunch of commands to build PHP Laravel application.
The Registry is an online image store for container images. Below mentioned options are few most popular registries.
Continuous delivery is a branch of continuous integration. It concentrates on automating the software delivery process. Source- Continuous Delivery Pipeline with Jenkins
How to write a Dockerfile for Scala Application?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 /*
Building Scala Base ImageThe Below mentioned command will build your scala base container image.
$ docker build -t scala-sbt:0.13
Dockerfile (Application)As Scala sbt doesn'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 XenonStack # 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 ImageThe below-mentioned command will build your application container image.
$ docker build -t <name application="" of="" scala="" your="">:<version application="" of="">
Publishing Scala Application Container ImageNow we publish the 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 &lt; privater registry name &gt; /<name of="" repository="" your="">:<version application="" of="" your="">
Creating Deployment files in Scala Application for Kubernetes
- Deployment File
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
- Service File
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 >
Deploying Scala Application in KubernetesScala Container Application can be deployed either by kubernetes Dashboard or Kubectl (Command line). I`m explaining the command line that you can use in production kubernetes cluster.
Now we have successfully deployed it's Application on Kubernetes.
$ kubectl create -f <name application="" of="">.deployment.yml $ kubectl create -f <name application="" of="">.service.yml
Verification of Dockerfile in Scala Application
We can verify application deployment either by using Kubectl or Kubernetes Dashboard. Below mentioned command will show you running pods of your application with status running/terminated/stop/created.
$ kubectl get po --namespace=<namespace kubernetes="" of=""> | grep <application name="">
Testing Dockerfile in Scala Application
Get the External Node Port using the below mentioned command. External Node Port is in the range from 30000 to 65000.
Launch web Browser and open any of the below-mentioned URLs.
$ kubectl get svc--namespace = < namespace of kubernetes > | grep < application name >
- http://<kubernetes master ip address >: <application service port number>
- http://<cluster ip address >: <application port number>
Develop and Deploy Python Application using Docker and Kubernetes and adopt DevOps in existing Python Applications. Source- Deploying Python Application on Docker & Kubernetes
Troubleshooting Dockerfile in Scala Application
- Check Status of Pods.
- Check Logs of Pods/Containers.
- Check Service Port Status.
- Check requirements/dependencies of the application.
How can XenonStack help you?
Continuous Integration & Continuous DeploymentEnable Secure Continuous Integration and Continuous Delivery Pipeline with Jenkins/Bamboo/TeamCity for delivery, automation, self-service environment, and On-demand. Deploy PHP Laravel Application to production by decreasing the time by the automation of entire delivery pipeline comprising build, deploy, test, and release.
Continuous Deployment Cloud HostingXenonStack Continuous Deployment Cloud Hosting Services for Scala Applications lets you clone your production to staging cluster in less than a minute. Develop, Deploy and Manage your PHP Laravel Application on leading Cloud Service Providers - AWS, Microsoft Azure, Google Cloud, and Container Environment - Kubernetes and Docker.
Application Modernization ServicesApplication Modernization Services enable the migration of monolithic applications to new Microservices architecture with Native Cloud Support including the integration of new functionality to create new value from the existing application.
- Read here about CI/CD Pipeline Tools and its Use Cases
- Explore here about Deploying Java Microservices Application on Kubernetes