CODEWITHSUNDEEP
docker
jonalv
jonalv

Reputation: 6116

How to read and write to mounted volume without running as root?

When mounting a volume with the following command:

docker run -t -i --volumes-from FOO BAR

the volumes from FOO are mounted with root as owner. I can't read and write to that without running as root as far as I know. Must I run as root or is there some other way?

I have tried by creating the folder with other owner before mounting but the mounting seems to overwrite that.

Edit: A chown would work if it could be done automatically after the mounting somehow.

Upvotes: 1

Views: 462

Answers (2)

BMitch
BMitch

Reputation: 263549

I'm not sure why you aren't able to change your folder permissions in your source image. This works without issue in my lab:

$ cat df.vf-uid
FROM busybox

RUN mkdir -p /data && echo "hello world" > /data/hello && chown -R 1000 /data

$ docker build -f df.vf-uid -t test-vf-uid .
...
Successfully built 41390b132940

$ docker create --name test-vf-uid -v /data test-vf-uid
e12df8f84a3b1f113ad5440b62552b40c4fd86f99eec44698af9163a7b960727

$ docker run --volumes-from test-vf-uid -u 1000 -it --rm busybox /bin/sh
/ $ ls -al /data
total 12
drwxr-xr-x    2 1000     root          4096 Aug 22 11:44 .
drwxr-xr-x   19 root     root          4096 Aug 22 11:45 ..
-rw-r--r--    1 1000     root            12 Aug 22 11:43 hello
/ $ echo "success" >/data/world
/ $ ls -al /data
total 16
drwxr-xr-x    2 1000     root          4096 Aug 22 11:46 .
drwxr-xr-x   19 root     root          4096 Aug 22 11:45 ..
-rw-r--r--    1 1000     root            12 Aug 22 11:43 hello
-rw-r--r--    1 1000     root             8 Aug 22 11:46 world
/ $ cat /data/hello /data/world
hello world
success
/ $ exit

Upvotes: 1

jonalv
jonalv

Reputation: 6116

So, what I ended up doing was mounting the volume to another container and change the owner (using uid of the owner I wanted in the final setup) from that container. Apparently uid's are uid's regardless. This means that I can run without being root in the final container. Perhaps there are easier ways to do it but this seems to work at least. Something like this: (untested code clip from my final solution)

docker run -v /opt/app --name Foo ubuntu /bin/bash
docker run --rm --volumes-from Foo -v $(pwd):/FOO ubuntu bash -c "chown -R 9999 /opt/app"
docker run -t -i --volumes-from FOO BAR

Upvotes: 0

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