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dockerenvironment-variablessystemd

How to load Docker environment variables in container

I'm building an image that is based on an ubuntu image with systemd. I need to start TigerVNC as a service which depends on some environment variables that I have defined in my Dockerfile, like the password.

FROM ubuntu-systemd

ENV VNC_PW="some-password"

ENTRYPOINT ["/lib/systemd/systemd"]

The unit file for this service has a line that is:

ExecStart=/usr/sbin/runuser -l root -c "/some/script.sh"

Since systemd has its own environment, I don't have access to the environment variables defined in my Dockerfile. I was expecting that running the script as root with a login shell (the '-l' flag) would give me access to these variables but it does not. I know the variables I need are in /proc/1/environ but I don't know how to load them, for example adding something in the .profile file for root.

Thank you.

Solution

  • A little bit tricky but I can load the environment variables in the /some/script.sh in the ExecStart property by including the following line:

    export `xargs --null --max-args=1 echo < /proc/1/environ`