Having trouble with some UI extensions

[flatsiedatsie]

As an experiment, today I created a 100% pure Webthings Gateway disk image using the Candle disk image creation script.

curl -H 'Cache-Control: no-cache' -sSl https://raw.githubusercontent.com/createcandle/install-scripts/main/create_latest_candle_dev.sh -o create_latest_candle_dev.sh; sudo chmod +x create_latest_candle_dev.sh; sudo CUTTING_EDGE=yes CREATE_DISK_IMAGE=yes SKIP_WEBTHINGS_GATEWAY=no bash ./create_latest_candle_dev.sh

Oddly, it seemed my UI extension addons weren't loading with the latest Github version. The HTML, CSS and JS loads, but the JS in unable to connect with the backend. It always returns a 404 error.

So then I updated the script to use the official 2.0.0 release. And then ensuring the original versions of gateway-addon-node and gateway-addon-python were loaded. But still no luck.

I added some debugging console.log lines, and it seemed like the api handlers list remained empty.

I assumed I must be doing something wrong.

My next step was to try running the official Docker image on my Mac, just to eliminate all Candle influences.

But here the result is the same: the addon is visible, but all requests end in 404.

.

(http or https makes no difference)

It's probably something in my addons that is out of spec. Are there any UI extension addons that I can test that you know work OK?

I checked that the api_handlers list was even supposed to be populated. But it seemed so. Here's what an API handler looks like in Candle:

  'photo-frame' => APIHandlerProxy {
    packageName: 'photo-frame',
    verbose: false,
    gatewayVersion: '',
    userProfile: {},
    preferences: {},
    plugin: Plugin {
      pluginId: 'photo-frame',
      addonManager: [AddonManager],
      pluginServer: [PluginServer],
      forceEnable: false,
      adapters: [Map],
      notifiers: Map(0) {},
      apiHandlers: [Map],
      exec: 'python3 {path}/main.py',
      execPath: '/home/pi/.webthings/addons/photo-frame',
      process: [Object],
      restart: true,
      restartDelay: 0,
      lastRestart: 0,
      pendingRestart: null,
      unloadCompletedPromise: null,
      nextId: 3,
      requestActionPromises: Map(0) {},
      removeActionPromises: Map(0) {},
      setPinPromises: Map(0) {},
      setCredentialsPromises: Map(0) {},
      notifyPromises: Map(0) {},
      apiRequestPromises: Map(0) {},
      unloding: false,
      logPrefix: 'photo-frame',
      startPromise: [Promise],
      stdoutReadline: [Interface],
      stderrReadline: [Interface],
      ws: [WebSocket]
    },
    unloadCompletedPromise: null
  },

(I've created a pull request to fix the "unloding" typo)

[flatsiedatsie]

Just found this:

2026-04-20 14:30:25.805 ERROR  : candle-theme: Traceback (most recent call last):
2026-04-20 14:30:25.805 ERROR  : candle-theme:   File "/home/node/.webthings/addons/candle-theme/main.py", line 5, in <module>
2026-04-20 14:30:25.806 ERROR  : candle-theme:     import gateway_addon
2026-04-20 14:30:25.806 ERROR  : candle-theme: ModuleNotFoundError: No module named 'gateway_addon'
2026-04-20 14:30:25.807 INFO   : Plugin: candle-theme died, code = 1 restarting after 5000
2026-04-20 14:30:25.942 ERROR  : photo-frame: Traceback (most recent call last):
2026-04-20 14:30:25.942 ERROR  : photo-frame:   File "/home/node/.webthings/addons/photo-frame/main.py", line 5, in <module>
2026-04-20 14:30:25.942 ERROR  : photo-frame:     import gateway_addon
2026-04-20 14:30:25.942 ERROR  : photo-frame: ModuleNotFoundError: No module named 'gateway_addon'
2026-04-20 14:30:25.944 INFO   : Plugin: photo-frame died, code = 1 restarting after 2000
2026-04-20 14:30:27.980 ERROR  : photo-frame: Traceback (most recent call last):
2026-04-20 14:30:27.981 ERROR  : photo-frame:   File "/home/node/.webthings/addons/photo-frame/main.py", line 5, in <module>
2026-04-20 14:30:27.981 ERROR  : photo-frame:     import gateway_addon
2026-04-20 14:30:27.981 ERROR  : photo-frame: ModuleNotFoundError: No module named 'gateway_addon'
2026-04-20 14:30:27.983 INFO   : Plugin: photo-frame died, code = 1 restarting after 3000
2026-04-20 14:30:30.828 ERROR  : candle-theme: Traceback (most recent call last):
2026-04-20 14:30:30.828 ERROR  : candle-theme:   File "/home/node/.webthings/addons/candle-theme/main.py", line 5, in <module>
2026-04-20 14:30:30.829 ERROR  : candle-theme:     import gateway_addon
2026-04-20 14:30:30.829 ERROR  : candle-theme: ModuleNotFoundError: No module named 'gateway_addon'
2026-04-20 14:30:30.832 INFO   : Plugin: candle-theme died, code = 1 restarting after 6000

[flatsiedatsie]

I tried adding the gateway module to the addons themselves. This seems to work, but now they get stuck on

APIHandler.__init__(self, addon_id)

[benfrancis]

@flatsiedatsie Have you been able to get any Python-based add-ons to work at all? I have a horrible feeling that gateway-addon-python is just broken in 2.0 since we upgraded the Python version in the Docker image. I had hoped WebThingsIO/gateway-addon-python#95 would fix that but we didn't get it into the release.

If it really is broken then I would love to get that fixed in 2.1. To be honest all of the add-ons I use on a daily basis use gateway-addon-node which is why I don't notice Python problems as much. I will try to find a Python-based add-on to reproduce the problem but let me know if you can provide reproduceable steps with an add-on already in the WebThings add-on directory.

We should probably also figure out a way to add an integration test that uses a Python-based add-on so that this can't regress again without us noticing.

[flatsiedatsie]

I was just coming to the same conclusion that the gateway-addon-python did not seem to be present in the Docker image 0_0. I opened an SSH into it and tried looking into its python paths.

The PR I made to make gateway-addon-python compatible with Python 3.13 should work fine if you take it at the last commit before your first comment.

This commit:
WebThingsIO/gateway-addon-python@c13686b

Direct link to the files:
https://github.com/WebThingsIO/gateway-addon-python/tree/c13686b2f5ae026c28b331b63e90befce7fb1bc2

Because I didn't quite know how to work with forks propertly yet the commits after that were for further changes I made to the gateway-addon-python to allow for transmitting meta data. But I assume you don't want that (yet ;-)).

Sorry, I didn't realise that you weren't including gateway-addon-python because of that 0_0.

In the meanwhile I've been experimenting with adding the gateway-addon-python to the Photo-Frame addon itself, and that did the trick.

But adding the gateway-addon-python to individual addons is a bad idea, right? Since that would mean that the addon is now 'locked' to a specific version of the gateway? Besides python addons already being locked to a python version, so that would create quite a complex github workflow matrix.

So I imagine/understand it's preferable to have the gateway to provide gateway-addon-pythonglobally.

Can you extract the gateway-addon-python version from the commit I linked?

but let me know if you can provide reproduceable steps with an add-on already in the WebThings add-on directory.

Heh, I literally asked you the same question a few comments ago:

It's probably something in my addons that is out of spec. Are there any UI extension addons that I can test that you know work OK?

You could try installing the Dashboard addon from github?
https://github.com/createcandle/dashboard

Or the Candle Store, though I'll have to make a quick fix if you would like to from there install other Python addons.
https://github.com/createcandle/candleappstore

Both are relatively simple. They are packaged as Python 3.9, but will run on newer Python versions without issue. Very much looking forward to an updated docker image, by the way.

We should probably also figure out a way to add an integration test that uses a Python-based add-on so that this can't regress again without us noticing.

Sounds good. But I have no knowledge/experience with unit tests yet. Self-taught programmer and all that. What would such a test need? I could create a super basic test addon that does/returns something after init to indicate it loaded ok, if you could then generate the test code around that?

Do you intend version 2.1 to run on Python 3.13?

I've highlighted all my questions in italic.

[flatsiedatsie]

In theory the Raspberry Pi disk image creation script should now install that specific commit (I hope).

I'll create a new disk image and test it.