[Podman] Re: bind-propagation=rshared has no effect

Giuseppe Scrivano gscrivan(a)redhat.com writes: > Rudolf Vesely via Podman podman(a)lists.podman.io writes: > > > On Wednesday, February 23rd, 2022 at 09:35, Giuseppe Scrivano gscrivan(a)redhat.com wrote: > > > > > Rudolf Vesely via Podman podman(a)lists.podman.io writes: > > > > > > > On Wednesday, February 23rd, 2022 at 08:52, Giuseppe Scrivano gscrivan(a)redhat.com wrote: > > > > > > > > > Rudolf Vesely via Podman podman(a)lists.podman.io writes: > > > > > > > > > > > On Wednesday, February 23rd, 2022 at 08:17, Giuseppe Scrivano gscrivan(a)redhat.com wrote: > > > > > > > > > > > > > Rudolf Vesely via Podman podman(a)lists.podman.io writes: > > > > > > > > > > > > > > > Hi Everybody, > > > > > > > > > > > > > > > > I tried to mount filesystem inside unprivileged container using > > > > > > > > > > > > > > > > fuse3 and it's working. The only thing I had to do was to mount > > > > > > > > > > > > > > > > /dev/fuse using "--device" and add "SYS_ADMIN" capability. > > > > > > > > > > > > > > > > Example: > > > > > > > > > > > > > > > > podman run \ > > > > > > > > > > > > > > > > -d \ > > > > > > > > > > > > > > > > --device=/dev/fuse \ > > > > > > > > > > > > > > > > --cap-add SYS_ADMIN \ > > > > > > > > > > > > > > > > localhost/myimage > > > > > > > > > > > > > > > > After that I can mount fuse inside. > > > > > > > > > > > > > > > > Now I'd like to access the mounted filesystem from another container in a pod or from the container host. In order to do that I used "bind-propagation=rshared" like this: > > > > > > > > > > > > > > > > podman run \ > > > > > > > > > > > > > > > > --mount=type=bind,source=/from,destination=/to,bind-propagation=rshared \ > > > > > > > > > > > > > > > > -d \ > > > > > > > > > > > > > > > > --device=/dev/fuse \ > > > > > > > > > > > > > > > > --cap-add SYS_ADMIN \ > > > > > > > > > > > > > > > > localhost/myimage > > > > > > > > > > > > > > > > When I mount fuse inside the container into "/to" or "/to/subfolder" I > > > > > > > > > > > > > > > > can again see / access the filesystem from inside of the container but > > > > > > > > > > > > > > > > I don't see it from the host / from another containers in a pod that > > > > > > > > > > > > > > > > mount "/from". > > > > > > > > > > > > > > > > Could you please tell me Am I missing something? > > > > > > > > > > > > > > mount points created from a rootless environment won't be propagated to > > > > > > > > > > > > > > the host, even if you specify rshared. > > > > > > > > > > > > > > They will be propagated in the rootless mount namespace, that you can > > > > > > > > > > > > > > access with "podman unshare". > > > > > > > > > > > > > > You first need to setup a mount point in the "podman unshare" > > > > > > > > > > > > > > environment, e.g.: > > > > > > > > > > > > > > $ podman unshare mount --make-shared --bind /from /from > > > > > > > > > > > > > > $ podman run -v /from:/to:rshared .... > > > > > > > > > > > > > > Is the mount accessible from other containers now? > > > > > > > > > > > > Hi Giuseppe, > > > > > > > > > > > > That was my initial trial since I don't need to access it from the > > > > > > > > > > > > host. I wanted to run two containers - the first mounting FUSE and > > > > > > > > > > > > the second running app that accesses the mounted data. > > > > > > > > > > > > I tried to run the two containers in a pod and outside of the pod. > > > > > > > > > > > > I tried to run the second with > > > > > > > > > > > > podman run --mount=type=bind,source=/from,destination=/to,bind-propagation=rshared > > > > > > > > > > > > and without > > > > > > > > > > > > podman run --mount=type=bind,source=/from,destination=/to > > > > > > > > > > > > and even with > > > > > > > > > > > > podman run --mount=type=bind,source=/from,destination=/to,bind-propagation=rshared --device=/dev/fuse --cap-add SYS_ADMIN > > > > > > > > > > > > But the second container does not see the mounted data. > > > > > > > > > > > > And if I mount the fuse on the first to "/from/mount" and I also > > > > > > > > > > > > "touch /from/abc" then the second container will see the directory > > > > > > > > > > > > "/to/mount" and the file "/to/abc" but the "/to/mount" directory will > > > > > > > > > > > > be empty. > > > > > > > > > > have you used `podman unshare mount --make-shared --bind /from /from` > > > > > > > > > > before creating the first container? > > > > > > > > > > Podman mailing list -- podman(a)lists.podman.io > > > > > > > > > > To unsubscribe send an email to podman-leave(a)lists.podman.io > > > > > > > > The fuse is mounted using rclone: https://rclone.org/commands/rclone_mount/ > > > > > > > > with option: --allow-other > > > > > > > > When I run rclone mount inside of the first container it looks like for example this: > > > > > > > > name_of_s3_mount: on /from type fuse.rclone (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) > > > > > > > > or when mounting as normal user inside of the container: > > > > > > > > name_of_s3_mount: on /from type fuse.rclone (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000,allow_other) > > > > > > > > And I can confirm that in both cases, all users inside of the first container can see the data. > > > > > > > > I've just tried inside of the first container after rclone mount: > > > > > > > > mount --make-shared --rbind /from /from > > > > > > > > and that has no effect. > > > > > > > > Forgot to mention that "/etc/fuse.conf" has "user_allow_other" option on both host and inside of the first container. > > > > > > you need to run `podman unshare mount --make-shared --bind /from /from` > > > > > > from the host before creating the container, not from the container. > > > > > > Please be careful, the `/from` directory must be the same one you use > > > > > > for the source for the bind mount when you create the container: > > > > > > $ mkdir /tmp/from > > > > > > $ podman unshare mount --make-shared --bind /tmp/from /tmp/from > > > > > > $ podman run -d --privileged --rm -v/tmp/from:/to:rshared alpine sh -c 'mount -t tmpfs tmpfs /to; touch /to/new-file; sleep 100' > > > > > > $ podman unshare ls /tmp/from > > > > > > new-file > > > > > > $ ls /tmp/from > > > > > > $ podman run --rm --rm -v/tmp/from:/to alpine sh -c 'ls /to' > > > > > > new-file > > > > > > The new-file is visible from the mount that can be shared among > > > > > > different containers, but it is not visible from the host. > > > > > > Podman mailing list -- podman(a)lists.podman.io > > > > > > To unsubscribe send an email to podman-leave(a)lists.podman.io > > > > Hi Giuseppe, > > > > The example is a superb explanation! Thank you very much Giuseppe. I managed to make it work with > > > > podman unshare mount --make-shared --bind /from /from > > > > podman run --mount=type=bind,source=/from,destination=/to,bind-propagation=rshared --device=/dev/fuse --cap-add SYS_ADMIN > > > > And I can see the data from host: > > > > podman unshare ls /from > > > > Or from another container > > > > podman run --volume=/from:/mnt -it --rm --name=client debian:bookworm bash > > > > Thank you very much. > > > > If I may bother you with one additional question, do you know if "bind-propagation=rshared" can be set within Kubernetes Pod Yaml file? > > > > I tried "mountPropagation: Bidirectional" like this: > > > > apiVersion: v1 > > > > kind: Pod > > > > metadata: > > > > name: rclone > > > > spec: > > > > containers: > > > > - name: app > > > > image: localhost/app > > > > volumeMounts: > > > > - name: dev-fuse > > > > mountPath: /dev/fuse > > > > - name: mydata > > mountPath: /to > > mountPropagation: Bidirectional > > securityContext: > > capabilities: > > add: > > - CAP_SYS_ADMIN > > > > > > volumes: > > > > - name: dev-fuse > > > > hostPath: > > > > path: /dev/fuse > > > > - name: mydata > > hostPath: > > type: Directory > > path: /from > > > > > > podman unshare umount /from # needs to be done before re-run / or just reboot > > > > podman unshare mount --make-shared --bind /from /from > > > > podman play kube file.yml > > > > And rclone is mounting properly inside but I can't see it from outside: > > > > podman unshare ls /from > > > > I'm thinking that Podman ignores "mountPropagation: Bidirectional" in the Yaml file since reading K8s docs, the setting does "bind-propagation=rshared". > > if it doesn't behave in the same way as the example I've provided, then > > it might be a bug. Could you please file an issue upstream for Podman? looks like a bug. I've opened a PR: https://github.com/containers/podman/pull/13320 Regards, Giuseppe