Prepare coursier artifact for offline use inside container - scala

Question

I have an sbt project producing my artifact xyz.
I would like to put it along with all its dependencies in the docker container so it can be used using
coursier launch --mode offline xyz
The important part is that preparation should take use of local cursier cache from host.
I tried
executing sbt publishLocal,
then resolving my artifact dependencies (cursier resolve xyz),
then preparing to directories - local & cache - by copying resolved artifact into them
then copying those directories into docker container (as coursier cache and ivy local respectively).
This didn't work because coursier doesn't list .pom and .xml files in its output. I tried copying whole directories (abc/1.0.0 instead of abc/1.0.0/some.jar) but AFAIK there is no reliable way to know how many folders up one has to go because maven and ivy have different dir structures.

Answer 1

while my usecase is not quite identical to yours -- I figure I'd write up my findings and maybe my solution works for you as well!
here's my sample dockerfile, I used this to install scalafmt in an offline-compatible way
FROM ubuntu:jammy
RUN : \
&& apt-get update \
&& apt-get install -y --no-install-recommends \
ca-certificates \
curl \
&& apt-get clean \
&& rm -rf /var/lib/apt/lists/* # */ stackoverflow highlighting bug
ARG CS=v2.1.0-RC4
ARG CS_SHA256=176e92e08ab292531aa0c4993dbc9f2c99dec79578752f3b9285f54f306db572
ARG JDK_SHA256=aef49cc7aa606de2044302e757fa94c8e144818e93487081c4fd319ca858134b
ENV PATH=/opt/coursier/bin:$PATH
RUN : \
&& curl --location --silent --output /tmp/cs.gz "https://github.com/coursier/coursier/releases/download/${CS}/cs-x86_64-pc-linux.gz" \
&& echo "${CS_SHA256} /tmp/cs.gz" | sha256sum --check \
&& curl --location --silent --output /tmp/jdk.tgz "https://download.java.net/openjdk/jdk17/ri/openjdk-17+35_linux-x64_bin.tar.gz" \
&& echo "${JDK_SHA256} /tmp/jdk.tgz" | sha256sum --check \
&& mkdir -p /opt/coursier \
&& tar --strip-components=1 -C /opt/coursier -xf /tmp/jdk.tgz \
&& gunzip /tmp/cs.gz \
&& mv /tmp/cs /opt/coursier/bin \
&& chmod +x /opt/coursier/bin/cs \
&& rm /tmp/jdk.tgz
ENV COURSIER_CACHE=/opt/.cs-cache
RUN : \
&& cs fetch scalafmt:3.6.1 \
&& cs install scalafmt:3.6.1 --dir /opt/wd/bin
the key to offline execution for me was to use cs fetch and set COURSIER_CACHE
here's the offline execution succeeding:
$ docker run --net=none --rm -ti cs /opt/wd/bin/scalafmt --version
scalafmt 3.6.1