While building a Docker image, how do I COPY a file into the image so that the resulting file is owned by a user other than root?
1 Answer
For versions v17.09.0-ce and newer
Use the optional flag --chown=<user>:<group> with either the ADD or COPY commands.
For example
COPY --chown=<user>:<group> <hostPath> <containerPath>
The documentation for the --chown flag is now live on the main Dockerfile Reference page.
Issue 34263 has been merged and is available in release v17.09.0-ce.
For versions older than v17.09.0-ce
Docker doesn't support COPY as a user other than root. You need to chown / chmod the file after the COPY command.
Example Dockerfile:
from centos:6
RUN groupadd -r myuser && adduser -r -g myuser myuser
USER myuser
#Install code, configure application, etc...
USER root
COPY run-my-app.sh /usr/local/bin/run-my-app.sh
RUN chown myuser:myuser /usr/local/bin/run-my-app.sh && \
chmod 744 /usr/local/bin/run-my-app.sh
USER myuser
ENTRYPOINT ["/usr/local/bin/run-my-app.sh"]
Previous to v17.09.0-ce, the Dockerfile Reference for the COPY command said:
All new files and directories are created with a UID and GID of 0.
History This feature has been tracked through multiple GitHub issues: 6119, 9943, 13600, 27303, 28499, Issue 30110.
Issue 34263 is the issue that implemented the optional flag functionality and Issue 467 updated the documentation.
