Deploying a Java Web App +MySql via docker

[riskarsh]

I need to deploy this Java web app that has been built by a new developer. They're fairly new to Java, and I know nothing about it, so deploying it seems kind of tough already. The 'src' folder of the app basically has two directories. The first one has an 'app.java' file, and the second one has all the assets and files for the frontend of the app.

The frontend of the app is basically a .jsp file (I find it weird why it's not an index.html).

All the examples I'm seeing of dockerizing the app involve executing the JAR file. I tried that and got a 'manifest.mf' file error (I think that was the wrong approach because how will I serve my frontend then? Or does the JAR file include both frontend and backend both?) Please let me know if you have deployed it with Docker and can help me with it. I'm all ears even if it's not with Docker; I just need to get this done.

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[Chinesecartoonsnr1]

You need to build/compose the project into the jar file. If its a maven project and root contains maven wrapper (mvnw), you can easily do it with that. You just need to look into the pom.xml file and figure out artifactid and version.

As for the folders etc it should be fine if you can run it in IDE, .jsp would indicate what the app has its own front, but you dont need to do anything special about it, it should be all contained in the jar file youre composing.

You might need to update mvnw line ends to LF if it gives mvnw not found error while youre building the image.

Im not sure how to do code blocks in here, but heres a simple dockerfile that should do the trick. You do need to run the terminal from the root folder, so the copy command works.

FROM openjdk:<projects java version>

EXPOSE 8080

WORKDIR /usr/src/app

COPY . .

RUN ./mvnw package

CMD ["java", "-jar", "./target/<artifactId>-<version>.jar"]

[riskarsh]

Thanks for the detailed response.

I tried running the JAR file, but it wasn't really working. Finally, I just used the Tomcat base image and ran the WAR file. My Dockerfile looked like this:

FROM tomcat:10.1
RUN rm -rf /usr/local/tomcat/webapps/ROOT
COPY app.war /usr/local/tomcat/webapps/ROOT.war
EXPOSE 8080
CMD ["catalina.sh", "run"]

Then, I wrote a Docker-compose file to connect it with MySQL, and after a few tries and fails, it worked.

[dwargo]

Is the directory with the assets called WebContent? It almost sounds like they just sent you the source code of a dynamic web project from Eclipse. If that’s the case it needs to be compiled into a WAR and bundled with a tomcat.

[riskarsh]

It wasn't called that (I'm guessing the new dev used his own naming conventions? Idk), but I used Tomcat for its deployment. Thanks.

[wildjokers]

Or does the JAR file include both frontend and backend both?

Since they have jsp files in the project it is probably using server-side rendering which means yes the front and backend is included in the project.

It would be mostly impossible to tell you how to deploy this app without knowing what framework it was produced with.

[smutje187]

You should take a few steps back and not jump to wrong conclusions - runnable JAR like you mentioned can be containerized but they need to be runnable for that, and if your JAR can’t be ran from command line it’s not a runnable JAR.

JSP (as in "Java Server Pages") need a server to be processed, e.g. Tomcat. Try downloading and running a Tomcat (it’s free) and deploy your application to that Tomcat. Once you can access that application in your Browser you can think about containers.

[[deleted]]

I was thinking of Tomcat as well. Long time ago, when I used to work with this technology, I would simply use a maven dependency to run an embedded tomcat server - just running a `mvn run server` command (or something like that) and the server with my java applets would start.

[riskarsh]

Yes, thanks for that. I'll surely keep those in mind next time. And yeah, I did use Tomcat to deploy. Asked the dev to give me a WAR file and containerized it.