The JoinChannel api call is fully deprecated for new Slack applications

[spkane]

Describe the bug
Slack has deprecated the channels.join api call and suggests to use conversations.join instead. API calls now return with method_deprecated for JoinChannel when you are using a Slack app created after June 10th (or so).

Slack API links:
https://api.slack.com/methods/channels.join
https://api.slack.com/methods/conversations.join

Code:

argo-events/sensors/triggers/slack/slack.go

Line 115 in 693e210

_, err = api.JoinChannel(channel)

To Reproduce

1. Create a new slack app
2. Try to use it with argo event Slack Triggers. You will get an error when argo events tries to send a message to Slack.

Expected behavior

1. argo-events should be able to send a message using both older and newer Slack Apps.

Environment (please complete the following information):

• OS: Linux (Kubernetes)

Additional context

JoinConversation is already written in the Slack package: https://github.com/slack-go/slack/blob/c664c83937182df61c6532cff2569ad50ec6b117/conversation.go#L536

JoinCoversation requires a channel id instead of channel name. This is different then the current call which expects a name. For backwards compatibility it would make sense to still expect a name and then lookup the ID and pass it to JoinConversation.

Note: github.com/slack-go/slack is the new community fork of github.com/nlopes/slack and is most likely what should be used going forward.

[spkane]

cc/ @lucassha

[spkane]

At the bare minimum, this code change fixes things:

sensors/triggers/slack/slack.go
114:	_, _, _, err = api.JoinConversation(channel)

[aeweidne]

Did you need to change the log level to get the error? I am seeing my Slack trigger fail silently on v0.16.0 but it is definitely getting the event from the gateway

[spkane]

@shimmerjs I don't think so, but it couldn't hurt. I am pretty sure that we at least got a warning that the call was deprecated. However, if your Slack app is new then this is almost certainly your issue. We are running a fork at the moment to work around it while we are testing.

[whynowy]

@spkane - Would you like to help do a testing with the change? I can give you RC images.

[spkane]

@whynowy Yes. I'd be happy to give it a test.