Request for system-files: micro-ros-agent-arnatious

store-requests
1

snap: https://snapcraft.io/micro-ros-agent-arnatious

Snap is a mirror of micro-ros-agent in order to produce an arm64 release, needed for a Core demo by the Ubuntu robotics team.

2

@arnatious can you please detail what files are needed to be accessed via system-files and for what purpose? Thanks.

3

Per upstream - it seems to have to do with netplug: https://github.com/micro-ROS/micro-ROS-Agent/blob/foxy/snap/snapcraft.yaml#L150.

I can’t find the original request for https://snapcraft.io/micro-ros-agent where the vendor originally sought approval to verify.

4

Ok. For future reference, what I was hoping was that you would say something like:

Request system-files access for write access to /dev/shm named micro-ros-agent-shm-netplug as the micro-ros agent request access to this for …

So the bit I don’t understand is the … - can you elaborate on why?

Also I notice that the micro-ros-agent snap in the store does not have this granted for it currently. Are you certain this is definitely needed?

5

Gotcha:

Request system-files access for write access to /dev/shm named micro-ros-agent-shm-netplug as the snap requires access to shared memory for the copy-less DDS implementation.

Attempting to run without access to shm produces the following error

2021-05-27 16:35:39.477 [RTPS_TRANSPORT_SHM Error] Failed to create segment 2fa1addd5b3223e0: Permission denied -> Function compute_per_allocation_extra_size

This is part of a recent ROS 2 update moving to a shared memory DDS(RTPS) implementation.

6

Thanks, so after looking at things a bit more I see the base policy for snaps allows the use of /dev/shm/snap.$SNAP_NAME.* - so would it be possible to adjust your snap to use a path such as /dev/shm/micro-ros-agent-arnatious.whatever instead? See Shared memory in /dev/shm rewriting for more details.

7

Since I’d rather not deviate from upstream (nor am I familiar with the package’s codebase enough to modify it), I looked into Help creating a strict snap that uses shared memory and Bashtop Linux resource monitor. That didn’t seem to change anything, however.

I opened an issue to track this https://github.com/micro-ROS/micro-ROS-Agent/issues/65.

8

@arnatious Just wondering if you were able to get this working?

9

@alexmurray no I could not, unfortunately. There appears to be a new snapcraft-preloads repo that is actively developed, but it does not advertise any fixes for shared memory. I’ve left an issue upstream and hopefully they’ll get around to investigating it themselves.

10

I am closing this request for now. If we get news from upstream, we can re open it if needed. Thanks!