Improvements for symfony/slack-notifier

The generic channel option

The problem:
Right now you can provide a channel= option, and you can pass nearly everything... 🤔

• CHANNEL is a channel, private group, or IM channel to send message to, it can be an encoded ID, or a name.

This is the full DSN: SLACK_DSN=slack://TOKEN@default?channel=CHANNEL

I tried a lot to figure out WHAT you need to pass exactly:

• If you want to wrote to the channel #support -> ?channel=support ✅
• If you want to wrote to the user @OskarStark -> ?channel=@OskarStark ✅
• If you want to wrote to the user @OskarStark you can also use the UserId, which can be found in your profile -> ?channel=U68xxxx 🤔 ✅
  

So far this looks ok, but there are some pitfalls we can avoid. One would think he can just use:

• ?channel=#support ❌ NO # sign allowed 😮
• ?channel=OskarStark ❌ NO, @ sign needed 😮
• ?channel=@U68xxxx ❌ NO @ sign allowed 😮

My proposal:
A new user= (or handle=) and user_id= parameter.
We can now validate, that a channel must not start with #, a user must start with @ and a user_id must not start with @ (maybe it also has a dedicated length which can be taken into account).

So valid DSN would be:

• slack://TOKEN@default?channel=support
• slack://TOKEN@default?user=@OskarStark // slack://TOKEN@default?handle=@OskarStark
• slack://TOKEN@default?user_id=@U68xxxx

The correct token - PR #39606

The Problem:
Because we switched back and forth from a token to a webhook_id, which can be considered a "token" too, it could be hard to find out, if you are using the correct token.

My proposal:
Let's validate the token syntax in the transport and give a clear error message.

Slack has a clear syntax for their tokens which makes us able to validate the syntax before we perform a request.

• Bot user token strings begin with xoxb-
• User token strings begin with xoxp-
• Workspace access token strings begin with xoxa-2

Questions

1. What type of token do you use?
2. Are you using any other ids, channel-names etc. ?

cc @malteschlueter as we both had some trouble in the past