Failed to pull source: unable to determine source type of '/usr/share/snapcraft/extensions/ros2'

[jkbeg]

Initially opened this issue canonical/snapcraft#5721
Since I did not get any response I suspect it was the wrong repository to address the docker issue.

Bug Description

Snapcraft fails to find its own extensions:

2025-08-22T07:04:11.745Z [snapcraft] Initializing parts lifecycle
2025-08-22T07:04:13.827Z [snapcraft] **Failed to pull source: unable to determine source type of '/usr/share/snapcraft/extensions/ros2'.**
2025-08-22T07:04:13.828Z [snapcraft] Full execution log: '/root/.local/state/snapcraft/log/snapcraft-20250822-070411.734995.log'
2025-08-22T07:04:13.956Z [pebble] Service "snapcraft" stopped unexpectedly with code 1

extensions path is hardcoded here:
usr/share/snapcraft/extensions
https://github.com/canonical/snapcraft/blob/df4ec6775a28d4a345c93d9f83a1193c0abc1c9d/snapcraft/extensions/extension.py#L135

but in latest docker container for snapcraft 8, ghcr.io/canonical/snapcraft:8_core22 (24050a02f9fe)
extensions are located here:
/usr/lib/python3.10/site-packages/extensions/ros2

To Reproduce

git clone https://github.com/snapcraft-docs/ros2-talker-listener-core22.git

cd ros2-talker-listener-core22

docker run -v $(pwd):/project ghcr.io/canonical/snapcraft:8_core22

Environment

Ubuntu 22.04 LTS, Docker 28.3.1

snapcraft.yaml

name: ros2-talker-listener
version: '0.1'
summary: ROS 2 Talker/Listener Example
description: |
 This example launches a ROS 2 talker and listener.

confinement: devmode
base: core22

parts:
 ros-demos:
   plugin: colcon
   source: https://github.com/ros2/demos.git
   source-branch: humble
   source-subdir: demo_nodes_cpp
   stage-packages: [ros-humble-ros2launch]

apps:
 ros2-talker-listener:
   command: opt/ros/humble/bin/ros2 launch demo_nodes_cpp talker_listener.launch.py
   extensions: [ros2-humble]

Relevant log output

docker run -v $(pwd):/project ghcr.io/canonical/snapcraft:8_core22
2025-08-22T07:04:05.252Z [pebble] Started daemon.
2025-08-22T07:04:05.284Z [pebble] POST /v1/services 16.330855ms 202 (http+unix)
2025-08-22T07:04:05.300Z [pebble] Service "snapcraft" starting: /bin/run-snapcraft.sh [ pack ]
2025-08-22T07:04:05.305Z [snapcraft] 
2025-08-22T07:04:05.305Z [snapcraft] WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
2025-08-22T07:04:05.305Z [snapcraft] 
2025-08-22T07:04:05.777Z [snapcraft] Get:1 http://archive.ubuntu.com/ubuntu jammy InRelease [270 kB]
2025-08-22T07:04:05.922Z [snapcraft] Get:2 http://security.ubuntu.com/ubuntu jammy-security InRelease [129 kB]
2025-08-22T07:04:05.938Z [snapcraft] Get:3 http://archive.ubuntu.com/ubuntu jammy-updates InRelease [128 kB]
2025-08-22T07:04:05.981Z [snapcraft] Get:4 http://archive.ubuntu.com/ubuntu jammy-backports InRelease [127 kB]
2025-08-22T07:04:06.031Z [snapcraft] Get:5 http://archive.ubuntu.com/ubuntu jammy/restricted amd64 Packages [164 kB]
2025-08-22T07:04:06.080Z [snapcraft] Get:6 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages [1792 kB]
2025-08-22T07:04:06.249Z [snapcraft] Get:7 http://archive.ubuntu.com/ubuntu jammy/multiverse amd64 Packages [266 kB]
2025-08-22T07:04:06.272Z [snapcraft] Get:8 http://archive.ubuntu.com/ubuntu jammy/universe amd64 Packages [17.5 MB]
2025-08-22T07:04:06.298Z [snapcraft] Get:9 http://security.ubuntu.com/ubuntu jammy-security/multiverse amd64 Packages [48.5 kB]
2025-08-22T07:04:06.317Z [pebble] GET /v1/changes/1/wait 1.032101461s 200 (http+unix)
2025-08-22T07:04:06.318Z [pebble] Started default services with change 1.
2025-08-22T07:04:06.408Z [snapcraft] Get:10 http://security.ubuntu.com/ubuntu jammy-security/universe amd64 Packages [1271 kB]
2025-08-22T07:04:06.948Z [snapcraft] Get:11 http://security.ubuntu.com/ubuntu jammy-security/restricted amd64 Packages [5235 kB]
2025-08-22T07:04:07.779Z [snapcraft] Get:12 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages [3253 kB]
2025-08-22T07:04:08.583Z [snapcraft] Get:13 http://archive.ubuntu.com/ubuntu jammy-updates/restricted amd64 Packages [5430 kB]
2025-08-22T07:04:09.285Z [snapcraft] Get:14 http://archive.ubuntu.com/ubuntu jammy-updates/universe amd64 Packages [1575 kB]
2025-08-22T07:04:09.452Z [snapcraft] Get:15 http://archive.ubuntu.com/ubuntu jammy-updates/multiverse amd64 Packages [75.9 kB]
2025-08-22T07:04:09.465Z [snapcraft] Get:16 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages [3569 kB]
2025-08-22T07:04:09.856Z [snapcraft] Get:17 http://archive.ubuntu.com/ubuntu jammy-backports/main amd64 Packages [83.2 kB]
2025-08-22T07:04:09.860Z [snapcraft] Get:18 http://archive.ubuntu.com/ubuntu jammy-backports/universe amd64 Packages [35.2 kB]
2025-08-22T07:04:09.986Z [snapcraft] Fetched 40.9 MB in 5s (8818 kB/s)
2025-08-22T07:04:09.986Z [snapcraft] Reading package lists...
2025-08-22T07:04:10.683Z [snapcraft] Building dependency tree...
2025-08-22T07:04:10.813Z [snapcraft] Reading state information...
2025-08-22T07:04:10.827Z [snapcraft] 8 packages can be upgraded. Run 'apt list --upgradable' to see them.
2025-08-22T07:04:11.745Z [snapcraft] Initializing parts lifecycle
2025-08-22T07:04:13.827Z [snapcraft] Failed to pull source: unable to determine source type of '/usr/share/snapcraft/extensions/ros2'.
2025-08-22T07:04:13.828Z [snapcraft] Full execution log: '/root/.local/state/snapcraft/log/snapcraft-20250822-070411.734995.log'
2025-08-22T07:04:13.956Z [pebble] Service "snapcraft" stopped unexpectedly with code 1
2025-08-22T07:04:13.956Z [pebble] Service "snapcraft" on-failure action is "shutdown", triggering failure shutdown
2025-08-22T07:04:13.956Z [pebble] Server exiting! Reason: <nil>

Additional context

No response

[syncronize-issues-to-jira]

Thank you for reporting your feedback to us!

The internal ticket has been created: https://warthogs.atlassian.net/browse/SNAPCRAFT-1249.

This message was autogenerated

[lengau]

Hi, thanks for the report! Yeah this looks like we're not organizing the extension scripts to somewhere where they'd be expected.

FWIW though, even once we fix this the ROS plugin won't work with snapcraft-rocks, as they depend on build snaps. The only supported way currently to use build snaps is to use the snapcraft snap.