Building Go apps with private modules in Docker - docker

Question

I'm trying to build a go project in a docker container that relies on private submodules.
I was hoping that --mount=type=ssh would pass my ssh credentials to the container and it'd work. Currently I can build locally with just make the GOPRIVATE variable set and the git config update.
Here is my relevant Dockerfile currently
# syntax = docker/dockerfile:experimental
FROM golang:1.14.3-alpine AS build
RUN apk add --no-cache git \
openssh-client \
ca-certificates
WORKDIR /src
ENV GIT_TERMINAL_PROMPT=1
ENV GOPRIVATE="gitlab.com/company_foo"
RUN git config --global url."ssh://git#gitlab.com".insteadOf "https://gitlab.com"
# Authorize SSH Host
# Skip Host verification for git
RUN mkdir -p /root/.ssh && \
chmod 0700 /root/.ssh && \
ssh-keyscan gitlab.com > /root/.ssh/known_hosts &&\
chmod 644 /root/.ssh/known_hosts && touch /root/.ssh/config \
&& echo "StrictHostKeyChecking no" > /root/.ssh/config
COPY go.mod go.sum .
RUN --mount=type=ssh mkdir -p /var/ssh && \
GIT_SSH_COMMAND="ssh -o \"ControlMaster auto\" -o \"ControlPersist 300\" -o \"ControlPath /var/ssh/%r#%h:%p\"" \
go mod download
COPY . .
RUN --mount=type=cache,target=/root/.cache/go-build go build -o api-server ./cmd/api-server
RUN --mount=type=cache,target=/root/.cache/go-build go build -o migrations ./cmd/migrations
I've also tried adding a CI_JOB_TOKEN with
RUN echo -e "machine gitlab.com\nlogin gitlab-ci-token\npassword ${CI_JOB_TOKEN}" > ~/.netrc
but this also didn't work. Perhaps I did it wrong.
All of this results in the failure:
revision v0.0.3: unknown revision v0.0.3
relating to one of our private repos.
Any advice would be appreciate.
I'm absolutely at a lost.

Answer 1

This workes for me.
FROM golang:1.14
ARG USERNAME=user1
ARG PASSWORD=secret
WORKDIR /app
ADD . .
ENV GOPRIVATE=private.git.local/*
RUN echo "machine private.git.local login $USERNAME password $PASSWORD" > ~/.netrc
RUN go build -o testGo main.go
CMD ["/app/testGo"]

Answer 2

pass your gitlab_token to docker file from gitlab_ci.yaml and do the following steps
RUN git config --global url."https://oauth2:$GITLAB_TOKEN#gitlab.com/".insteadOf "https://git#gitlab.com/"
add your repo as GO_PRIVATE
ENV GOPRIVATE=gitlab.com/*
copy .netrc file to docker root
COPY confidential/.netrc /root/.netrc
.netrc file will have the following structure
machine gitlab.com
login gitlab_user
password p#$$word