Docker for Java Developers

Docker for Java Developers
4th Anniversary Java Colombo Meetup
Image Credit: Jordan Novet/VentureBeat

Agenda - Session 1
● Introduction to Docker
● Why Docker is Important?
● Let’s Run Docker
● Docker Demo
● Why Need of Docker Cluster?
● Brief Introduction to K8S
● Kubernetes Demo
By Lakmal Warusawithana
Director Cloud Architecture ,WSO2 Inc
Vice President - Apache Stratos
http://twitter.com/lakwarus

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Session 1

Virtual Machine vs Container
https://sysadmincasts.com/episodes/31-introduction-to-docker

What is Docker?
https://sysadmincasts.com/episodes/31-introduction-to-docker

Why Docker?
● Achieve agility and control for Development and IT Operations
teams to build, ship, and run any app, anywhere
https://www.docker.com

Docker Use Cases
https://www.docker.com

How to setup Docker on Linux
● curl -sSL https://get.docker.com/ | sh
● Docker client, the Docker daemon, and
any containers run directly on your
localhost
● Can address ports on a Docker
container using standard localhost
addressing such as localhost:PORT or
Container-IP:PORT

How to setup Docker on Mac
● Goto https://docs.docker.
com/engine/installation/mac/
● Docker daemon is running inside a
Linux VM called default
● The default is a lightweight Linux VM
(~24MB download, and boots in
approximately 5s)

How to setup Docker on Windows
● Goto https://docs.docker.
com/engine/installation/windows/
● Docker daemon is running inside a
Linux VM called default
● The default is a lightweight Linux VM
(~24MB download, and boots in
approximately 5s)

Docker and Windows Containers
● More info :https://www.docker.com/microsoft

Why Need of Docker Cluster?
● Avoid single point of failure
● Make horizontally scalable
● Have more granular management for distributed applications
(microservices)
● Self healing systems

What is Kubernetes?
● Manage a cluster of Linux containers as a single system to
accelerate Dev and simplify Ops.
● Initiated by Google
● Massive community support

Kubernetes Architecture
Node1 Node2 Node n
Physical Network
Master
Overlay Network (Flannel/OpenVSwitch/Weave)APIServer
Scheduler
ControllerManager
etcd

Key Concepts of Kubernetes
● Pod - A group of Containers
● Labels - Labels for identifying pods
● Proxy/Service - A load balancer for Pods
● etcd - A metadata service
● cAdvisor - Container Advisor provides resource
usage/performance statistics
● Replication Controller - Manages replication of pods
● Scheduler - Schedules pods in worker nodes
● API Server - Kubernetes API server

Kubernetes Replication Controller

Pet Store Sample
https://github.com/wso2/msf4j/tree/master/samples/petstore/deployment

Pet Store Sample - Deployment View
https://github.com/wso2/msf4j/tree/master/samples/petstore/deployment

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Session 2

Agenda - Session 2
● Running a Microservice JAR in a Docker
container
● Building a Docker image with Maven
● Running a Java server application in a
Docker container
● Talking to the Docker API in Java
● Next generation continuous delivery
with Jenkins & Docker
● Deploying Java server applications in
production
Imesh Gunaratne
Senior Technical Lead, WSO2

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Running a Microservice JAR
in a Docker Container

Evolution of SOA
http://www.pwc.com/us/en/technology-forecast/2014/cloud-computing/features/microservices.html

What is a Microservice?
● “Microservice is an architectural style for developing a single
application as a suite of small services, each running in its
own process and communicating with lightweight mechanisms,
often an HTTP resource API” - Martin Fowler
http://martinfowler.com/articles/microservices.html

Monoliths Vs Microservices

Deployment Model

WSO2 MSF4J Hello World Sample
package org.wso2.msf4j.example;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
/**
* Hello service resource class.
*/
@Path("/hello")
public class HelloService {
@GET
@Path("/{name}")
public String hello(@PathParam("name") String name) {
return "Hello " + name;
}
}

WSO2 MSF4J Hello World Sample
git clone https://github.com/wso2/msf4j.git
# Build msf4j, this requires JDK 1.8
cd msf4j/
mvn clean install
# Build hello world sample
cd samples/helloworld/
mvn clean install
# Run self contained JAR
java -jar target/helloworld-*.jar
curl http://localhost:8080/hello/java-colombo

How to run a Microservice JAR in a
Docker Container
>docker run
# Mount local folder to container
-v ~/dev/wso2/msf4j/samples/helloworld/target/:/tmp/
# Ports to be exposed
-p 8080:8080
# Docker image tag
-t java
# Command to be run
java -jar /tmp/helloworld-1.0.0-SNAPSHOT.jar

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Building a Docker Image
with Maven

Docker Maven Plugins
● Spotify Docker Maven Plugin
○ https://github.com/spotify/docker-maven-plugin
● Fabric8io Docker Maven Plugin
○ https://github.com/fabric8io/docker-maven-plugin
● Alex Collins Docker Maven Plugin
○ https://github.com/alexec/docker-maven-plugin
● Wouter Danes Docker Maven Plugin
○ https://github.com/wouterd/docker-maven-plugin

Using Spotify Docker Maven Plugin
Add Docker Maven plugin to the pom.xml file:
<build>
<plugins>
<plugin>
<groupId>com.spotify</groupId>
<artifactId>docker-maven-plugin</artifactId>
<version>0.4.0</version>
<configuration>
<imageName>helloworld</imageName>
<baseImage>java</baseImage>
<entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint>

<resources>
<resource>
<targetPath>/</targetPath>
<directory>${project.build.directory}</directory>
<include>${project.build.finalName}.jar</include>
</resource>
</resources>
</configuration>
</plugin>
</plugins>
</build>

Using Spotify Docker Maven Plugin
1. Build Hello World Docker image using Maven:
>mvn clean package docker:build
2. List Docker images:
>docker images
3. Run Hello World Docker container:
>docker run -p 8080:8080 helloworld

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Running a Java Server
Application in a
Docker Container

Running Tomcat in Docker
FROM java:8-jre
ENV CATALINA_HOME /usr/local/tomcat
ENV PATH $CATALINA_HOME/bin:$PATH
RUN mkdir -p "$CATALINA_HOME"
WORKDIR $CATALINA_HOME
...
ENV TOMCAT_MAJOR 8
ENV TOMCAT_VERSION 8.0.32
ENV TOMCAT_TGZ_URL https://www.apache.org/dist/tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-
tomcat-$TOMCAT_VERSION.tar.gz
RUN set -x
&& curl -fSL "$TOMCAT_TGZ_URL" -o tomcat.tar.gz
&& curl -fSL "$TOMCAT_TGZ_URL.asc" -o tomcat.tar.gz.asc
&& gpg --batch --verify tomcat.tar.gz.asc tomcat.tar.gz
&& tar -xvf tomcat.tar.gz --strip-components=1
&& rm bin/*.bat
&& rm tomcat.tar.gz*
EXPOSE 8080
CMD ["catalina.sh", "run"]

Running Tomcat in Docker
● Dockerfile:
○ https://github.com/docker-library/tomcat
● Run Tomcat in Docker container:
○ docker run -it --rm -p 8888:8080 tomcat:8.0

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Talking to the Docker API
in Java

Docker API Clients for Java
● Docker Java API
○ https://github.com/docker-java/docker-java
● Docker Client
○ https://github.com/spotify/docker-client
● jClouds Docker API Client
○ https://github.com/jclouds/jclouds-labs/tree/master/docker
● Other API Clients:
● https://docs.docker.com/engine/reference/api/remote_api_client_libraries/

Docker Java Client Sample
[docker images cmd]
https://github.com/docker-java/docker-java/wiki
DockerClientConfig config = DockerClientConfig.createDefaultConfigBuilder()
.withDockerHost("tcp://192.168.99.100:2376").build();
DockerClient dockerClient = DockerClientBuilder.getInstance(config).build();
ListImagesCmd cmd = dockerClient.listImagesCmd();
System.out.println("Executing docker images command...");
List<Image> images = cmd.exec();
for(Image image : images) {
System.out.println(new Date(image.getCreated() * 1000) + " - "
+ image.getId() + " - "
+ image.getRepoTags()[0] + " - "
+ image.getVirtualSize());
}

Docker Java Client Sample
[docker run cmd]
https://github.com/docker-java/docker-java/wiki
DockerClientConfig config = DockerClientConfig.createDefaultConfigBuilder()
.withDockerHost("tcp://192.168.99.100:2376").build();
DockerClient dockerClient = DockerClientBuilder.getInstance(config).build();
String imageTag = "tomcat:8.0";
System.out.println("Starting container: " + imageTag);
CreateContainerResponse container = dockerClient.createContainerCmd(imageTag).exec();
dockerClient.startContainerCmd(container.getId()).exec();

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Next Generation Continuous
Delivery with
Jenkins & Docker

Jenkins Pipeline Plugin
http://devops.com/2016/01/21/12670/
Formerly known as the Workflow plugin. Originally inspired by the Build Flow Plugin.

Jenkins Pipeline Plugin UI
https://wiki.jenkins-ci.org/display/JENKINS/Delivery+Pipeline+Plugin

Jenkins Pipeline works with Docker
http://devops.com/2016/01/21/12670/

Jenkins Pipeline Tutorial
https://github.com/jenkinsci/workflow-plugin/blob/master/TUTORIAL.md

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Deploying Java Server
Applications in Production
with Docker

Problems with Standalone Docker
● Limited scalability
● Potential risk of Single Point of
Failure (SPOF)

Docker Cluster Management Solutions
Kubernetes Docker SwarmApache Mesos

Docker Swarm Architecture
https://docs.docker.com/swarm/swarm_at_scale/01-about/

Apache Mesos Architecture
https://www.digitalocean.com/community/tutorials/an-introduction-to-mesosphere

Kubernetes Architecture
https://mesosphere.com/blog/2015/09/25/kubernetes-and-the-dcos/

Deploying Tomcat in Kubernetes [1]
https://github.com/imesh/docker-for-java/tree/master/kubernetes
Node IP: 172.17.8.102
Port: 8080
Domain Name: tomcat
IP: 10.2.10.20
Port: 8080
NodePort: 32001
Protocol: TCP
Pod 1 Pod 2 Pod n
Tomcat Service
L1
L1 L1 L1
Node
Tomcat
Replication
Controller

Deploying Tomcat in Kubernetes [2]
https://github.com/imesh/docker-for-java/tree/master/kubernetes
apiVersion: v1
kind: ReplicationController
metadata:
name: tomcat
labels:
name: tomcat
spec:
replicas: 1
selector:
name: tomcat
template:
metadata:
labels:
name: tomcat
spec:
containers:
-
name: tomcat
image: tomcat:8.0
ports:
-
containerPort: 8080
protocol: "TCP"
apiVersion: v1
kind: Service
metadata:
labels:
name: tomcat
name: tomcat
spec:
type: NodePort
sessionAffinity: ClientIP
ports:
# ports that this service should serve on
-
name: 'http'
port: 8080
targetPort: 8080
nodePort: 32001
# label keys and values that must match in
order to receive traffic for this service
selector:
name: tomcat
Tomcat ServiceTomcat Replication
Controller

Sample Code
https://github.com/imesh/docker-for-java

Thank you!
https://wiki.jenkins-ci.org/display/JENKINS/CloudBees+Docker+Custom+Build+Environment+Plugin

Docker for Java Developers

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