hi,
I'm actually using docker with nested bind mounts to run 2 instances of the same application with different configurations.

let's say i have an app running on the host and reading it's configuration from the directory /home/user/.config/app_config.

i can run a second instance with a different configuration running this docker command:

docker run -it \
-u user \
-v /home/user:/home/user \
-v /home/user/.config/alternative_app_config:/home/user/.config/app_config \
app_image

with this command the application running into the container reads its configuration from the host /home/user/.config/alternative_app_config directory, leaving the other configuration dir untouched.


is there a way to get this kind of behaviour without docker?
thanks!

Yes, provided you are root user. It would be much easier and flexible if your application accepted a command line option that specifies the location of the configuration file (like the --php-ini option of php).

unfortunately that's not an application of mine... how could i do the same with root privileges..?

Now that you ask it, it would require `chroot` as well

Here's a pretty good intro to chroot https://help.ubuntu.com/community/BasicChroot

... but there might be a simpler solution, it's hard to know without some particulars. i.e. running the app as a different user from it's own home.

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