How to mount docker tmpfs with exec,rw flags?

Question

What command line options can be used for enabling a tmpfs (temporary file system) inside a Docker container, that is rw (read/write) accessible and files on this fs (file system) are executable?

Example would be a shared memory tmpfs with 1GByte size, but standard flag is noexec

( shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=1048576k) )

with:

docker -it --shm-size=1G alpine /bin/sh

Answer 1

You can pass mount parameters to the --tmpfs parameter, e.g. --tmpfs /mytmp:exec would allow execution of files.

$ docker run --rm -it --tmpfs /mytmp:exec ubuntu bash -c "mount | grep mytmp"
tmpfs on /mytmp type tmpfs (rw,nosuid,nodev,relatime)

Answer 2

If you don't need namespace isolation, then you can use host IPC namespace (--ipc=host):

$ docker run --rm -it --ipc=host alpine sh -c 'mount | grep shm'
tmpfs on /dev/shm type tmpfs (rw,seclabel,nosuid,nodev)

vs

$ docker run --rm -it --shm-size=1G alpine sh -c 'mount | grep shm'
shm on /dev/shm type tmpfs (rw,seclabel,nosuid,nodev,noexec,relatime,size=1048576k)`