How to pass credentials to sbt build cli? - scala

Question

I'm trying to Dockerize an old sbt build that needs access to a private nexus repo. I've previously been using a local credentials file referenced from the build.sbt, but that doesn't really fit my use currently since I want to bootstrap everything from a Dockerfile build. I rather not have to output stuff to a file and then copy it into my docker build container but rather just pass it as docker ARG's.
Under
https://www.scala-sbt.org/1.0/docs/Publishing.html
I read I can pass it like so:
credentials += Credentials("Some Nexus Repository Manager",
"my.artifact.repo.net", "admin", "admin123")
So therefore I figured I could do something like:
ARG REPO_USER
ARG REPO_PWD
RUN sbt ";credentials += Credentials(\"Some Nexus Repository Manager\", \"repo.host.com\", ${REPO_USER}, ${REPO_PWD}) ;package"
and then run
docker build . --build-arg REPO_USER=foobar --build-arg REPO_PWD=*****
in my Dockerfile but that didn't work. I still get:
Unable to find credentials for [Sonatype Nexus Repository Manager # repo.host.com]
Is there any nice way to pass repo credentials to sbt from cli?
Update:
I tried a a file approach but that didn't solve the problem so I guess I might be on the wrong track on what's actually wrong here.
RUN echo "realm=Sonatype Nexus Repository Manager" >> .credentials && \
echo "host=repo.host.se" >> .credentials && \
echo "user=$REPO_USER" >> .credentials && \
echo "password=$REPO_PWD" >> .credentials && \
export SBT_CREDENTIALS=.credentials && \
sbt package
Update 2
I think this is no longer a Docker question at all since I've debugged it in the docker container sbt simply wouldn't pick my creds up any way I passed it according to the sbt docs.
I'll answer my own question.

Answer 1

You can use environment variables. You can set them in dockerfile either straight or from args. Something like this:
ARG REPO_USR
ARG REPO_PWD
ENV REPO_USR = ${REPO_USR}
ENV REPO_PWD = ${REPO_PWD}
Then you can use the environment variables in sbt:
val repoUser = sys.env.get("REPO_USR").getOrElse("")
val repoPass = sys.env.get("REPO_PWS").getOrElse("")
credentials += Credentials("Repo Realm", "repo.url.com", repoUser, repoPass)
Then you can basically pass args to docker build and they will be passed on to sbt.

Answer 2

The sbt docs are misleading at best or simply just wrong. After debugging this to bits in the docker container I found that there was no way I could pass the creds cli so they got picked up. The SBT_CREDENTIALS variable just doesn't work either.
This comment finally saved me: SBT is unable to find credentials when attempting to download from an Artifactory virtual repo
The least intrusive way I've got working is to add an sbt config file in the docker image's home dir:
RUN mkdir .sbt/0.13/plugins && \
echo "credentials += Credentials(\"Sonatype Nexus Repository Manager\", \"repo.host.se\", \"$REPO_USER\", \"$REPO_PWD\")" >> .sbt/0.13/plugins/creds.sbt
RUN sbt package