[Add] Implement Slack Socket Mode support

[JCMarques15]

Description

This PR introduces support for Slack Socket Mode, enabling real-time message processing using websockets. This feature enhances the Slack integration by allowing for more efficient and responsive communication, and a way to bypass ingress restrictive networks.

Changes

• Added Slack Socket Mode handler in server.py
• Created start_socket_mode function in slack/app.py
• Implemented conditional logic to use Socket Mode when SLACK_WEBSOCKET_TOKEN is set
• Added an example script slack_websocket_test.py for testing the Slack websocket handler

How to Test

1. Set the following environment variables:
   • SLACK_BOT_TOKEN
   • SLACK_SIGNING_SECRET
   • SLACK_WEBSOCKET_TOKEN
2. Run the application and verify that the Slack integration connects using Socket Mode
3. Test sending messages through Slack and ensure they are processed correctly

Additional Notes

• The existing HTTP handler remains active when only SLACK_BOT_TOKEN and SLACK_SIGNING_SECRET are provided
• When SLACK_WEBSOCKET_TOKEN is set, the application will prioritize Socket Mode over the HTTP handler

[dokterbob]

@JCMarques15 This is a great feature, thanks for the contrib!

I would really like to have at least basic unit test coverage here. That way, we can ensure that Slack integration stays stable going forward. Please let me know whether you're willing to give that a try! I recommend using Claude Sonnet to help along if you get stuck (but I'm happy to offer support as well!).

[JCMarques15]

Hi @dokterbob, sorry for the late reply—it’s been a hectic few weeks!

Thanks for the detailed suggestions; they’re super helpful. I’ll give the unit testing a try and work on monkeypatching AsyncSocketModeHandler and AsyncApp to cover both legacy and websocket behavior. I’m still getting familiar with this kind of setup, so it might take me a bit of time, but I’m happy to dive in.

If I hit any roadblocks or it ends up taking longer than expected, I’ll focus on submitting a PR for the cookbook and documentation instead. Let me know if there’s anything else I should keep in mind as I get started!

[willydouhard]

What is the status on this?

[dokterbob]

@JCMarques15 Friendly poke. :)

[JCMarques15]

My apologies for the delay. The end and beginning of the year have been quite demanding work-wise, and I wasn’t able to find the time to address this earlier.

I’ve now picked it up and am actively working on it. You can expect an update by the end of next week. Thank you for your patience!

[JCMarques15]

Hi @dokterbob I have made the changes you had requested.

I’ve moved the testing script to the cookbook as a minimal Slack bot integration example and added documentation for the new behaviour in the docs repo.

Additionally, I’ve added unit tests for both the legacy and websocket Slack behaviours using AsyncSocketModeHandler and AsyncApp with mocks, as suggested. These tests assert that Slack functions are properly called and simulate relevant callback hooks.

I believe I’ve covered everything you outlined, but I’d really appreciate it if you could take a quick look to confirm whether this aligns with your expectations or if anything still needs to be adjusted.

The relevant PRs are:
cookbook repository: #195
docs repository: #230

[gowtham3105]

@JCMarques15 @dokterbob What is the status on this ?

[JCMarques15]

Hi @gowtham3105!

The PR is currently waiting for final review from the maintainers. I've added the requested unit tests and documentation, so from a technical standpoint it should be ready to go.

@dokterbob when you have a moment, would you be able to take a look? Happy to make any additional adjustments if needed.

Thanks for your interest in this feature!

[gowtham3105]

Hi @hayescode @asvishnyakov

This PR is pending for review since quite some time, can one of you please have a look ?

[asvishnyakov]

@JCMarques15 Can you please fix the failing test and linting issues?

[JCMarques15]

Hi @asvishnyakov. I have dealt with the unused import and weird space character. For the test error:

Problem

The test_slack_socket_mode.py test was failing in CI/CD with KeyError: 'slack' but passing locally.

Root Cause

The issue was with the lazy import registry system. When using:

with patch("chainlit.slack.app.AsyncSocketModeHandler", autospec=True):

The patch() function tries to resolve the string path by accessing chainlit.slack as an attribute, which triggers the __getattr__ method in chainlit/__init__.py. However, slack is not included in the lazy import registry, causing a KeyError.

Solution

I changed the test to use object-based patching instead of string-based patching:

# Import the module first
slack_app_mod = importlib.import_module("chainlit.slack.app")

# Patch the object directly
with patch.object(slack_app_mod, "AsyncSocketModeHandler", autospec=True) as handler_cls:

This bypasses the lazy import registry entirely by importing the module directly via importlib.import_module().

An alternative would be to add slack to the lazy import registry in chainlit/__init__.py, similar to how other optional integrations are handled. However, I chose the direct import approach for this test to avoid potential side effects or changes to the main module's import behavior, especially since I'm not fully familiar with all the implications of modifying the registry.

I hope this fixes everything as requested.

[JCMarques15]

Apologies, I hadn’t realized Ruff was being used as the formatter. My local setup was applying Black by mistake. I’ve corrected the formatting in the affected file, and it should now pass all CI/CD checks.

[gowtham3105]

@asvishnyakov Can you please check the changes?
I want to use this in slack socket mode changes in my chatbot. This is hosted in our internal could so, exposing a public endpoint is not possible