Read content in /writable/system-data/etc

For helping this snap to read system buildstamp. I would like to read
/writable/system-data/etc/buildstamp inside the snap.
Although this snap is installed with --devmode , it still cannot read /writable/system-data .

$ snap run --shell qabro
$ cd /writable/
$ ls -l
total 0
$ cd /var/lib/snapd/hostfs/writable/
$ ls -l
total 0

Is there any way I could read the content in /writable/system-data/etc ?

I guess you should plug system-files interface?

Can you not read /etc/buildstamp within the snap’s mount namespace directly? Why do you need to access it through /writable/system-data? /etc should be mounted from /writable outside your snap and should be synced, though there are sometimes issues with writable-paths.

For reference, /writable is considered an implementation detail and is not exposed to snaps, we don’t allow accessing it through any interface and recently we started unmounting /writable from the snap’s mount namespace as well, so the /writable you see in a snap’s mount namespace will be the empty /writable from the base snap on your system.