Merge pull request #336 from flatcar/kai/unshare

sysext: Add debugging commands

docs/provisioning/sysext/_index.md

@@ -184,4 +184,19 @@ systemd:
 This configuration will enable the `systemd-sysupdate.timer` unit that will check every 2-6 hours for a new Docker sysext image available from the latest release of [`sysext-bakery`][sysext-bakery].
 Use `arm64` instead of `x86-64` for arm64 machines.
 
+## Debugging
+
+You can list the contents of a systemd-sysext image like this (assuming an image without dm-verity):
+
+```
+sudo unshare -m sh -c "mount docker-compose-2.18.1.raw /tmp && cd /tmp && find ."
+# Remember that only the "usr" or "opt" folder will be used for the overlay
+```
+
+To get more information about found incompatibilities during merging, enable the debug output:
+
+```
+sudo SYSTEMD_LOG_LEVEL=debug systemd-sysext refresh
+```
+
 [sysext-bakery]: https://github.com/flatcar/sysext-bakery

docs/setup/releases/update-strategies.md

@@ -305,7 +305,7 @@ sudo git diff --no-index /usr/share/flatcar/etc /etc
 You can also see what files got created under the real `/etc` with the following commands:
 
 ```sh
-sudo unshare -m "umount /etc; ls -lahR /etc"
+sudo unshare -m sh -c "umount /etc; ls -lahR /etc"
 ```
 
 ### Configure a post-install update hook