How to make vert.x project work in a Docker container?

Question

I downloaded a vert.x starter project from http://start.vertx.io/ and would like to run the compiled binary with java -jar .. inside a Docker container.

Current invocation command:

mvn package exec:java -DskipTests

Current Dockerfile:

FROM java:10
COPY target/project-1.0-SNAPSHOT.jar project.jar
ENTRYPOINT java -jar project.jar

which gives the following error message when run

no main manifest attribute, in /project/target/vertx-start-project-1.0-SNAPSHOT.jar

Is there a simpler way than building a full deployment assembly as is usually done with Maven?

score 2 · Answer 1 · edited Jan 28 '19 at 14:57

When you run a command like so:

mvn package exec:java

The vert.x specfic configuration will make Maven create:

SNAPSHOT.jar
SNAPSHOT-fat.jar

like so:

the fat.jar has all the files in it, so you only need to copy that jar file to the Docker image.

FROM openjdk:10-jre-slim
COPY target/SNAPSHOT-fat.jar fat.jar
ENTRYPOINT java -jar fat.jar

you build the docker image with:

docker build -t foo .

then run the docker image as a container with:

docker run -it foo

score 0 · Answer 2 · answered Jan 27 '19 at 06:29

0

A runnable jar requires a Main-Class entry in MANIFEST.MF with the name of the class to launch.

You will most likely also need your dependencies copied in.

Consider this a full deployment of your application.

answered Jan 27 '19 at 06:29

Thorbjørn Ravn Andersen

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All that needs to be done is to use the fat.jar file and copy that to the Docker image, please see my answer. – Alexander Mills Jan 27 '19 at 06:38
Please don’t spam all other answers with a reference t your own answer. Let the voting mechanism work instead. – Thorbjørn Ravn Andersen Jan 27 '19 at 11:22
i honestly had to hold myself back from criticizing the other answers as poor and downvoting them. – Alexander Mills Jan 27 '19 at 19:47
Ah, you answered your own question - sorry, but didn't expect that an 18k user would ask such a poorly worded question. Therefore I suggest that you edit both to clearly indicate that this question is about vert.x because your answer is not valid generally but only for vert.x projects. – Thorbjørn Ravn Andersen Jan 28 '19 at 00:33
Now that you understand the question, can you add an answer that is more general and not only for vertx projects? I will accept it if so, ty – Alexander Mills Jan 28 '19 at 00:42
@AlexanderMills No. That would just be a duplicate and closed as such. Just finish what you started. – Thorbjørn Ravn Andersen Jan 28 '19 at 00:53
i dont know the answer besides using a fat.jar file, i dont use java or vertx much – Alexander Mills Jan 28 '19 at 01:32
I edited your question so it is hopefully not just a poor and downvotable duplicate of https://stackoverflow.com/q/574594/53897 but now a vert.x specific question to fit your own answer. – Thorbjørn Ravn Andersen Jan 28 '19 at 14:56
do you think anything else is necessary in the Dockerfile or is that one jar enough – Alexander Mills Jan 28 '19 at 17:37

score 0 · Answer 3 · answered Jan 27 '19 at 06:32

0

Like what Thorbjørn said, this command executes a "runnable" jar, which means it should have packed with a MANIFEST.MF that points to some certian main method in your project

answered Jan 27 '19 at 06:32

Ahmad Khundaqji

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All that needs to be done is to use the fat.jar file and copy that to the Docker image, please see my answer. – Alexander Mills Jan 27 '19 at 06:38

How to make vert.x project work in a Docker container?

3 Answers3