Support communities <-> workspace bridging

[Half-Shot]

(CC: @benparsons, @Cadair)

Communities in Matrix are really not all that great, but sources tell me that we are unlikely to see a replacement in the near future. We can write a sufficiently abstract implementation that would work with future communities stuff though.

Things that need to be considered

• A admin command / provisioning button that maps in a whole workspace. This would:
  • Create a community with all the information presented neatly in the HTML view.
    • Org description, links, various bits of info.
    • Instructions on how to join the community?
  • Create channels (public) inside the community automatically.
  • Create all workspace users

Things that need to be considered more:

• How do private channels work in terms of joining them
• Alias rooms aren't a thing in Slack, because....
• How do we model access control here:
  • Allow everyone
  • Deny based on homeserver?
  • Deny based on group membership?
  • Deny based on actual slack authentication for the user?

*Denying access is also a problem. We cannot maintain a whitelist for a room effectively on matrix, so it would have to be kick on join.

[olmari]

An tought: AFAIK for denying based on HS would be "easy" server adming toggle to (automatically? manually? Per what exactly in bridge settings?) set said room to exist only on said HS (aka not federate that room).

[Half-Shot]

@olmari The current federation toggle is a bit meh, because it's enabled at room creation time and so you are stuck with it forever. However, I guess it's a good plan for those wanting to be truly secluded.

[dreamflasher]

This is a crucial/blocking missing feature for me: I have a work slack, and multiple slack project workspaces, mixing all of them in the main matrix view would make matrix unusable. (writing this in the assumption that having many slack workspaces is the default for slack users)

[rdbisme]

This is also interesting for me. Have multiple workspaces I need to re-add on the Slack desktop app everytime I change PC.

It would be cool to bridge them as Matrix communities in order to have them forever in the Matrix app.

[expipiplus1]

Communities in Matrix are really not all that great, but sources tell me that we are unlikely to see a replacement in the near future.

Spaces support is nearly here, supposedly an improvement to communities

[georgyo]

Spaces are now in beta, and they are extremely awesome! They are very quickly getting adopted by all my communities.

Having each slack workspace become a matrix space would be absolutely perfect, and really melt any friction in migrating from slack to matrix.

Very much looking forward to seeing this become a reality.

[andrewshadura]

Spaces have been out of beta for a long time, it would be great if this would be implemented.