Slack notifications from Github Actions

A while back I wrote about moving my deployment scripts away from Codeship into Github Actions. This has continued to work, but as I noted it did leave me without notifications in Slack. Time to fix this.

There are a few ways of enabling notifications. The best way involves creating Slack apps with incoming webhooks, but this involves a lot of faff (especially on a free Slack instance). The ever-useful Phil Wilson found a much simpler alternative.

Enter the Github Slack app.

The setup is very easy:

• Add Github app to Slack
• Log in to Github app as whichever user should be receiving notifications
• Authorise it to talk to your Github account in Github

All three of these are documented in the above link.

Then it's a case of setting up the notifications you want within the Slack app channel. I used the following:

/github unsubscribe $account/$repo issues pulls commits
/github subscribe $account/$repo workflows:{event:"push"}

The first removed the overly noisy notifications from a whole bunch of Things on the account. The second enables notifications from workflows (ie Actions) - mine are triggered on "push" events. Docs for the workflow configuration can be found on the integration page.

And behold! Notifications!

When Github updates its SSH host key

I wrote recently about deploying to remote servers via Github Actions. I use this blog partially as a place to write bits of useful documentation and this is a quick note on how to fix those deploys when Github updates its SSH host key. It took me an evening of fiddling around while watching TV to get this right, so I don't want to have to think about it next time.

On the target server, remove the old github.com entries and add the new key into known_hosts:

ssh-keygen -R github.com
curl -L https://api.github.com/meta | jq -r '.ssh_keys | .[]' | sed -e 's/^/github.com /' >> ~/.ssh/known_hosts

And that should be enough to make it all work again.

These commands courtesy of the Github blog. Essentially, this post is distilling that one for future reference.