Docker build failed to copy a file - docker

Question

Hi I am new to Docker and trying to wrap around my head on how to clone a private repo from github and found some interesting link issues/6396
I followed one of the post and my dockerfile looks like
FROM python:2.7 as builder
# Deploy app's code
#RUN set -x
RUN mkdir /code
RUN mkdir /root/.ssh/
RUN ls -l /root/.ssh/
# The GITHUB_SSH_KEY Build Argument must be a path or URL
# If it's a path, it MUST be in the docker build dir, and NOT in .dockerignore!
ARG SSH_PRIVATE_KEY=C:\\Users\\MyUser\\.ssh\\id_rsa
RUN echo "${SSH_PRIVATE_KEY}"
# Set up root user SSH access for GitHub
ADD ${SSH_PRIVATE_KEY} /root/.ssh/id_rsa
RUN ssh -o StrictHostKeyChecking=no -vT git#github.com 2>&1 | grep -i auth
# Test SSH access (this returns false even when successful, but prints results)
RUN git clone git#github.com:***********.git
COPY . /code
WORKDIR /code
ENV PYTHONPATH /datawarehouse_process
# Setup app's virtualenv
RUN set -x \
&& pip install tox \
&& tox -e luigi
WORKDIR /datawarehouse_process
# Finally, remove the $GITHUB_SSH_KEY if it was a file, so it's not in /app!
# It can also be removed from /root/.ssh/id_rsa, but you're probably not
going
# to COPY that directory into the runtime image.
RUN rm -vf ${GITHUB_SSH_KEY} /root/.ssh/id*
#FROM python:2.7 as runtime
#COPY --from=builder /code /code
When I run docker build . from the correct location I get this error below. Any clue will be appreciated.
c:\Domain\Project\Docker-Images\datawarehouse_process>docker build .
Sending build context to Docker daemon 281.7MB
Step 1/15 : FROM python:2.7 as builder
---> 43c5f3ee0928
Step 2/15 : RUN mkdir /code
---> Running in 841fadc29641
Removing intermediate container 841fadc29641
---> 69fdbcd34f12
Step 3/15 : RUN mkdir /root/.ssh/
---> Running in 50199b0eb002
Removing intermediate container 50199b0eb002
---> 6dac8b120438
Step 4/15 : RUN ls -l /root/.ssh/
---> Running in e15040402b79
total 0
Removing intermediate container e15040402b79
---> 65519edac99a
Step 5/15 : ARG SSH_PRIVATE_KEY=C:\\Users\\MyUser\\.ssh\\id_rsa
---> Running in 10e0c92eed4f
Removing intermediate container 10e0c92eed4f
---> 707279c92614
Step 6/15 : RUN echo "${SSH_PRIVATE_KEY}"
---> Running in a9f75c224994
C:\Users\MyUser\.ssh\id_rsa
Removing intermediate container a9f75c224994
---> 96e0605d38a9
Step 7/15 : ADD ${SSH_PRIVATE_KEY} /root/.ssh/id_rsa
ADD failed: stat /var/lib/docker/tmp/docker-
builder142890167/C:\Users\MyUser\.ssh\id_rsa: no such file or
directory

Answer 1

From the Documentation:
ADD obeys the following rules:
The path must be inside the context of the build; you cannot ADD
../something /something, because the first step of a docker build is
to send the context directory (and subdirectories) to the docker
daemon.
You are passing an absolute path to ADD, but you can see from the error:
/var/lib/docker/tmp/docker-builder142890167/C:\Users\MyUser\.ssh\id_rsa:
no such file or directory
It is being looked for within the build context. Again from the documentation:
Traditionally, the Dockerfile is called Dockerfile and located in the
root of the context.
So, you need to place the RSA key somewhere in the directory tree which has it's root at the path that you specify in your Docker build command, so if you are entering docker build . your ARG statement would change to something like:
ARG SSH_PRIVATE_KEY = .\.ssh\id_rsa