In this Hands-on Lab, we will show you how to take a traditional Java EE app, and compile it to run in a lightweight Java container. The app we’ve chosen is an old Java EE demo called MoviePlex 7 that was originally written to run in Wildfly 3. You can find our fork of the repo in our javaee-demo repository on GitHub. In fact, if you were to take that repository, and lift the movieplex7-1.0-SNAPSHOT file, you could run that in a Java Application Server, such as WebLogic, Wildfly, or WebSphere.
- Task 0: The Play with Docker Lab Environment
- Task 1: Building the App in a Container
- Task 2: Adding a New Front-end
- Task 3: Moving from Wildfly to Tomcat EE
- Task 4: Push to Docker Trusted Registry
- Task 5: Deploy on Universal Control Plane with Kubernetes
This workshop is only available to people in doing a Hands-on-Lab at DockerCon 2018.
If none of these apply to you, contact your local Docker Meetup Chapter and ask if there are any scheduled workshops. In the meantime, you may be interested in the labs available through the Play with Docker Classroom.
There are three main components to the Play With Docker (PWD) interface.
In this section of the lab, you are going to take a Java EE web app running on Wildfly, move it to Tomcat EE, and run it in a Docker container.
The easiest way to move an enterprise Java app into Docker is create a WAR file and deploy it to the app server.
In the Docker Enterpise Edtion panel, click on manager1 to get the manager window.
Clone the lab repo into the PWD lab. Remember, you can click the command or manually type it into the terminal window.
git clone https://github.com/dockersamples/javaee-demo
cd javaee-demo
You will build the application using Maven and deploy it to container to see how it looks. Building and deploying the application can be done without having either Maven or an application server on your computer.
First, look at how the original application works. You can do this by building the application in Docker using a Wildfly container which was the app server the project first used. Although the GitHub repo contains an EAR file, you will build the application from source and deploy it using a multi-stage build Dockerfile. Here’s the text of the two-stage Dockerfile.wildfly file that you can find in the movieplex7 directory.
FROM maven:3-jdk-7 AS app
WORKDIR /usr/src/movieplex7
COPY pom.xml .
RUN mvn -B -f pom.xml -s /usr/share/maven/ref/settings-docker.xml dependency:resolve
COPY . .
RUN mvn -B -s /usr/share/maven/ref/settings-docker.xml package -DskipTests
FROM jboss/wildfly
RUN /opt/jboss/wildfly/bin/add-user.sh admin Admin --silent
COPY --from=app /usr/src/movieplex7/target/movieplex7-1.0-SNAPSHOT.war .
EXPOSE 8080 9990
CMD ["/opt/jboss/wildfly/bin/standalone.sh", "-b", "0.0.0.0", "-bmanagement", "0.0.0.0"]
The first part of the Dockerfile uses a maven container to build the war file. Instead of building the application locally, it is built inside the container with the tool chain needed to compile the application. In the second part of the Dockerfile, you use a Wildfly container and copy the war file built in the previous container to the app server for deployment.
There are a few additional commands to expose the ports and start Wildfly.
First, set an environment variable DTR_HOST using the DTR host name defined on your Play with Docker landing page. You'll find the DTR host address in the PWD window.
```bash
$ export DTR_HOST=<dtr hostname>
$ echo $DTR_HOST
```
Next, here's how to build the app:
cd movieplex7
docker image build -t movieplex7 -f Dockerfile.wildfly .
This creates a Docker image with the application deployed on Wildfly.
To run the application:
docker container run -d -p 8080:8080 --name movieplex7 movieplex7
To see the app running, copy the UCP hostname from Session Information and add port 8080 and the application:
http://ip172-18-0-11-bahdje2ubbhg0095k6s0.direct.ee-beta2.play-with-docker.com:8080/movieplex7-1.0-SNAPSHOT
Your app is deployed in Docker now, with no code changes and running in the original app server. Feel free to play around with the functionality of the site to understand the app better.
One of the big advantages of containers is that they can ease the process of updating older applications by replacing parts of the application as needed. Java EE also makes it easy to consume the output of your application in different ways. This allows you to easily add a different client to an application.
React Client In this section, you will update the Movie Plex 7 application by adding more attributes to the movie entity and also updating the presentation layer by writing a new client using React. Don’t worry, all the code is provided, you don’t need to know React.
As you saw earlier, the Java Server Faces client was rather sparse and old-fashioned looking. You want to make the movie listing to include movie posters as well as more information about each movie. To do that, you will add a few attributes to the Movie entity, and include a path to a movie poster, and more information about the cast and the movie rating.
The Movie Plex 7 application includes a REST interface for querying movies. This simplifies writing a new client because you can use the API and get data via REST. The javascript client is a bit more descriptive than the original Java Server Faces client.
In order to separate the new client from the existing client and server, you will deploy the React client in a separate container. To get ready to build the React client, stop and remove the running container, and then change the directory from movieplex7 to the root of the project.
docker container stop movieplex7
docker container rm movieplex7
cd ..
Due to a quirk in how React is built, and the base url of the Play with Docker lab, before you build the React client you need to run a script to inject the host URL into the Dockerfile.
./add_ee_kube_pwd_host.sh
cat ./react-client/Dockerfile
You should see something similar to the example below on the second line of the Dockerfile.
FROM node:latest AS build
API_HOST=ip172-18-0-8-baug157oeapg00e0p4hg.direct.ee-beta2.play-with-docker.com:8080
React uses Node.js to build a static site for the interface. The Dockerfile is much simpler than the one for the movieplex7 app, using a single-stage build. When it runs, it will start a simple Node server that serves the React pages, and exposes them on port 3000. We’ll deploy it in the next section.
FROM node:latest
ENV API_HOST=pwd10-0-16-3-8080.host4.labs.play-with-docker.com
WORKDIR /usr/src/react-client
COPY . .
RUN npm install
RUN npm run build
EXPOSE 3000
CMD ["npm", "run", "start"]
In Step 1, you compiled and deployed the Movie Plex 7 application from source by building it in a Maven container and then deploying it in a Wildfly container. The JavaServer Faces front-end was integrated into the the same application image.
In this step you will make three changes. First, as described in the previous step, you will use a React front-end deployed in a second container. Second, you will deploy the app in a Tomcat EE application server instead of Wildfly. Last, you will deploy both at the same time using a Docker Compose file.
The new front-end is described in the last section, so take a look at the new Dockerfile that deploys your app using the Tomcat Server.
more movieplex7/Dockerfile
FROM maven:latest AS app
WORKDIR /usr/src/movieplex7
COPY pom.xml .
RUN mvn -B -f pom.xml -s /usr/share/maven/ref/settings-docker.xml dependency:resolve
COPY . .
RUN mvn -B -s /usr/share/maven/ref/settings-docker.xml package -DskipTest
FROM tomee:8-jre-7.0.2-plume
# tomcat-users.xml sets up user accounts for the Tomcat manager GUI
# and script access for Maven deployments
WORKDIR /usr/local/tomee/
ADD tomcat/tomcat-users.xml conf/
ADD tomcat/web.xml conf/
# copy and deploy application
WORKDIR /usr/local/tomee/webapps/
COPY --from=app /usr/src/movieplex7/target/movieplex7-1.0-SNAPSHOT.war .
# start tomcat7
EXPOSE 8080
CMD ["catalina.sh", "run"]
You’ll see that the first stage is very similar to Dockerfile.wildfly. Only instead of using maven:3-jdk-7 as the base image, it uses maven:latest. There’s still no code change, you are still compiling the code into a WAR file. The second stage is a bit different, because it uses a different application server. But the end result is the same application running on both.
You now have two Dockerfiles, one to build the Java Movie Plex 7 application and another to build the React javaScript client. Running a build for each will result in two images.
cd movieplex7
docker image build -t movieplex7-tomee .
cd ../react-client
docker image build -t react-client .
Now that the images are built, we'll push them into Docker Trusted Registry (DTR). DTR Docker Trusted Registry (DTR) is the enterprise-grade image storage solution from Docker. You install it behind your firewall so that you can securely store and manage the Docker images you use in your applications and to make them available on Docker Universal Control Plane (UCP). UCP is the enterprise-grade cluster management solution from Docker and it helps you manage your Docker swarm and applications through a single interface.
In a production environment we want to be able to control access to resources such as images, networks and storage. Docker Enterprise Edition implements Role Based Access Control (RBAC) which determines who gets access to a resource, what level of access (create, change, run, delete), and provides a way to enforce access within your environment. To learn more about RBAC, check out the access control documentation and an example use case.
Login into DTR and push the images. The DTR repository hostname is in the Session Information panel.
docker login $DTR_HOST
Username: admin
Password:
Login Succeeded
Tag the images with the DTR hostname and account name, i.e. admin, to register them.
docker image tag movieplex7-tomee $DTR_HOST/admin/movieplex7-tomee
docker image tag react-client $DTR_HOST/admin/react-client
Next we'll create an empty repository for each of the images. First click on the DTR button the left side bar and log into DTR using the credentials in the Session Information panel.
To create a new repository click on Repositories on the left panel and click on New Repository. Create an entry for react-client and movieplex7-tomee.
Push the images to DTR from the command line:
docker image push $DTR_HOST/admin/react-client
docker image push $DTR_HOST/admin/movieplex7-tomee
The images are now available to use in Universal Control Plane.
Click on the UCP button to launch the UCP window.
Next we'll deploy the application using Kubernetes as the orchestrator. Click on Kubernetes on the side menu and click on Create.
Select default for Namespace and copy the yaml into the window and replace the DTR address with the URL of the DTR. Click on Create to deploy the application.
The Kubernetes manifest defines services and deployments for each of the services that make up the voting app. Kubernetes pods are mortal and are created and destroyed as needed. Services are an abstraction of a logical set of pods and a policy for accessing them. In Deployments, the Pod is defined using a Pod Template or .spec.template. It has the same schema as a Pod except it is nested in the template. It defines the container(s), specifying the image used, environmental variables such as user name and password, ports and volume mounts. The Service spec.type is set to LoadBalancer which provisions a load balancer for the service and makes the application available outside of the cluster. In the Deployment manifest spec.replicas sets the number of replicas to 2 which is the same as the Docker stack file.
---
apiVersion: v1
kind: Service
metadata:
labels:
app: movieplex7
name: movieplex7
spec:
type: LoadBalancer
ports:
- name: movieplex7
port: 8080
selector:
app: movieplex7
---
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: movieplex7
labels:
app: movieplex7
spec:
selector:
matchLabels:
app: movieplex7
replicas: 1
template:
metadata:
labels:
app: movieplex7
spec:
containers:
- name: movieplex7
image: <DTR HOST>/admin/movieplex7-tomee:latest
ports:
- containerPort: 8080
hostPort: 8080
name: movieplex7
---
apiVersion: v1
kind: Service
metadata:
labels:
app: react-client
name: react-client
spec:
type: LoadBalancer
ports:
-
name: react-client
port: 80
selector:
app: react-client
---
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: react-client
labels:
app: react-client
spec:
selector:
matchLabels:
app: react-client
replicas: 1
template:
metadata:
labels:
app: react-client
spec:
containers:
- name: react-client
image: <DTR HOST>/admin/react-client:latest
ports:
- containerPort: 80
hostPort: 80
name: react-client
After kubernetes has deployed the application, the Controllers window shows thw deployments and services as well as the pods deployed.
Click on Load Balancers brings up the Load Balancer window and clicking on movieplex7 displays a detailed configuration menu that includes the external URL of the application. Note that the URL assigns a port that isn't 8080, but because the hostPort is set in the movieplex7 deployment, the application is also accessible through port 8080. This is important because the react-client uses a known endpoint to retrieve data from the REST interface.
Note the URL of the movieplex7 application.
In the case of the react-client, port 80 is already in use by Docker Enterprise Edition and kubernetes assigns an unused port.
The react-client can still send requests to the movieplex7 REST endpoint, but uses another port in its URL instead of port 80.
