CODEWITHSUNDEEP
dockermavenbuilddocker-compose
Santanu
Santanu

Reputation: 25

Running mvn install from Dockerfile gives error but, running it from inside the container is successful

I have a project at https://github.com/picklu13/dockerbuildtest. When I run docker-compose up --build from the builders directory, the build errors with "[ERROR] The goal you specified requires a project to execute but there is no POM in this directory (/app). Please verify you invoked Maven from the correct directory. -> [Help 1]"

Now if I comment out the last line of the Dockerfile # RUN mvn clean package and run docker-compose up --build, the container starts up. Then I go into the container with docker exec -it <id> bash and run mvn clean install which succeeds.

My question is, why did the first build fail with no pom.xml error although it was already present.

Upvotes: 0

Views: 7340

Answers (2)

Pierre B.
Pierre B.

Reputation: 12943

In your first case, you're running build from builders directory but the context passed to Docker does not contains pom.xml (it contains what is in your current directory as per docker-compose instruction context: .)

In your second case, up will mount your project's directory in app with:

 volumes:
      - ~/dockerbuildtest/:/app/

Meaning that ~/dockerbuildtest/pom.xml will appear in container as /app/pom.xml. Running mvn from app now works.

why did the first build fail with no pom.xml error although it was already present

It was not present: in first build, there is no pom.xml copied into your image (see COPY instruction).

You could ensure your context contains pom.xml by running your build command from your project's root directory and specifying Dockerfile such as:

    build:
      # will use current directory as build context
      # by running from your project's root dir, context will contain pom.xml
      context: .
      # path to Dockerfile is relative to where build command is run
      dockerfile: builders/Dockerfile

And copy your pom.xml in your Dockerfile such as:

# [...]
WORKDIR /app

# copy pom.xml from context into image
COPY pom.xml /app/pom.xml

# run from /app directory which now contains a pom.xml, should work
RUN mvn clean package

Upvotes: 3

JustLudo
JustLudo

Reputation: 1790

You mount a volume and I think by the time the container boots up, the specified resource is not at said location, due to the volume not yet being loaded.

You could try to not use a volume and instead use a COPY command in your dockerfile to make sure the resource is actually in /app before the container starts.

[EDIT] Even if you scenario does not allow you to do so, I recommend still testing with the COPY to see if this indeed is a volume problem.

Upvotes: 1

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