Bridging Carpentries Slack channels to Matrix

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In which I try to save some of the history of The Carpentries by bridging Slack to its open source cousin Matrix

It looks like I’ve accidentally taken charge of bridging a bunch of The Carpentries Slack channels over to Matrix. Given this, it seems like a good idea to explain what that sentence means and reflect a little on my reasoning. I’m more than happy to discuss the pros and cons of this approach

If you just want to try chatting in Matrix, jump to the getting started section

What are Slack and Matrix?

Slack (see also on Wikipedia), for those not familiar with it, is an online text chat platform with the feel of IRC (Internet Relay Chat), a modern look and feel and both web and smartphone interfaces. By providing a free tier that meets many peoples’ needs on its own Slack has become the communication platform of choice for thousands of online communities, private projects and more.

One of the major disadvantages of using Slack’s free tier, as many community organisations do, is that as an incentive to upgrade to a paid service your chat history is limited to the most recent 10,000 messages across all channels. For a busy community like The Carpentries, this means that messages older than about 6-7 weeks are already inaccessible, rendering some of the quieter channels apparently empty.

As Slack is at pains to point out, that history isn’t gone, just archived and hidden from view unless you pay the low, low price of $1/user/month. That doesn’t seem too pricy, unless you’re a non-profit organisation with a lot of projects you want to fund and an active membership of several hundred worldwide, at which point it soon adds up. Slack does offer to waive the cost for registered non-profit organisations, but only for one community. The Carpentries is not an independent organisation, but one fiscally sponsored by Community Initiatives, which has already used its free quota of one elsewhere rendering the Carpentries ineligible. Other umbrella organisations such as NumFocus (and, I expect, Mozilla) also run into this problem with Slack.

So, we have a community which is slowly and inexorably losing its own history behind a paywall. For some people this is simply annoying, but from my perspective as a facilitator of the preservation of digital things the community is haemhorraging an important record of its early history.

Enter Matrix.

Matrix is a chat platform similar to IRC, Slack or Discord. It’s divided into separate channels, and users can join one or more of these to take part in the conversation happening in those channels. What sets it apart from older technology like IRC and walled gardens like Slack & Discord is that it’s federated.

Federation means simply that users on any server can communicate with users and channels on any other server. Usernames and channel addresses specify both the individual identifier and the server it calls home, just as your email address contains all the information needed for my email server to route messages to it. While users are currently tied to their home server, channels can be mirrored and synchronised across multiple servers making the overall system much more resilient. Can’t connect to your favourite channel on server X? No problem: just connect via its alias on server Y and when X comes back online it will be resynchronised.

The technology used is much more modern and secure than the aging IRC protocol, and there’s no vender lock-in like there is with closed platforms like Slack and Discord. On top of that, Matrix channels can easily be “bridged” to channels/rooms on other platforms, including, yes, Slack, so that you can join on Matrix and transparently talk to people connected to the bridged room, or vice versa.

So, to summarise:

  • The current Carpentries Slack channels could be bridged to Matrix at no cost and with no disruption to existing users
  • The history of those channels from that point on would be retained on and accessible even when it’s no longer available on Slack
  • If at some point in the future The Carpentries chose to invest in its own Matrix server, it could adopt and become the main Matrix home of these channels without disruption to users of either Matrix or (if it’s still in use at that point) Slack
  • Matrix is an open protocol, with a reference server implementation and wide range of clients all available as free software, which aligns with the values of the Carpentries community

On top of this:

  • I’m fed up of having so many different Slack teams to switch between to see the channels in all of them, and prefer having all the channels I regularly visit in a single unified interface;
  • I wanted to see how easy this would be and whether others would also be interested.

Given all this, I thought I’d go ahead and give it a try to see if it made things more manageable for me and to see what the reaction would be from the community.

How can I get started?


Please remember that, like any other Carpentries space, the Code of Conduct applies in all of these channels.

First, sign up for a Matrix account. The quickest way to do this is on the Matrix “Try now” page, which will take you to the Riot Web client which for many is synonymous with Matrix. Other clients are also available for the adventurous.

Second, join one of the channels. The links below will take you to a page that will let you connect via your preferred client. You’ll need to log in as they are set not to allow guest access, but, unlike Slack, you won’t need an invitation to be able to join.

  • #general — the main open channel to discuss all things Carpentries
  • #random — anything that would be considered offtopic elsewhere
  • #welcome — join in and introduce yourself!

That’s all there is to getting started with Matrix. To find all the bridged channels there’s a Matrix “community” that I’ve added them all to: Carpentries Matrix community.

There’s a lot more, including how to bridge your favourite channels from Slack to Matrix, but this is all I’ve got time and space for here! If you want to know more, leave a comment below, or send me a message on Slack (jezcope) or maybe Matrix (! I’ve also made a separate channel for Matrix-Slack discussions: #matrix on Slack and Carpentries Matrix Discussion on Matrix

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