bass loop

A continuous Bass service. Currently geared towards GitHub but other integrations should be possible.

See the Announcement for more details - a proper README will come shortly!

demo

See Bass Loop demo for a repo to play around with.

installation

Note: you only need to install Bass Loop if you're planning to run your own server.

Using Go 1.18+:

go install github.com/vito/bass-loop/cmd/bass-loop@latest

the plan

• A GitHub app for running Bass GitHub event handlers in-repo (kinda like GitHub actions).
  • A shorthand for the common case of running checks.
• A web UI for viewing thunk output (so a 'details URL' can be set on GitHub checks).
  • A thunk that contains secrets should default to private visibility.
• A SSH server so that users can bring their own workers (i.e. their local machine).
  • A method for passing secrets to thunks via the runner so sensitive values never even leave the machine.
  • A method for PR authors to satisfy PR checks using their own workers, without the repo maintainer having to run them.
• Scalable - everyone brings-their-own-worker, so only the Loop has to be scaled out.
• Make it a little more friendly. Right now the frontpage is pretty cryptic; it's purely driven by the 'navigating from GitHub' use case at the moment, but a dash of metadata could help tie things back in the other direction.

GitHub App configuration

First, go to Register new GitHub App. This guide will walk you through the creation steps. Don't worry too much as everything can be changed later.

Set the GitHub App name to whatever you want, but keep in mind this is a global (to GitHub) namespace. Set whatever description you deem appropriate - this will show up when users view your app. Feel free to steal the description from my Bass CI app.

Set the Homepage URL to the external URL of your app e.g. https://example.com. If you're kicking the tires, use ngrok to serve your local Loop to the public internet:

use an address like https://abcd-123-45-67-89.ngrok.io.

Skip the "Identifying and authorizing users" section - it's unused.

Skip the "Post installation" section too unless you've got your own page to take them to. Loop might provide one of these someday; it'd be nice UX for getting started.

Webhook

Enable webhooks.

Set Webhook URL to e.g. https://example.com/integrations/github/events

Set a Webhook secret for a real public installation so people can't spoof webhook payloads.

Repository permissions

Checks: Read and write. This is Loop's main function.

Contents: Read-only. Needed to receive push events. Also needed to fetch the repo's project.bass script.

The remaining permissions are up to you; it depends on what type of events you want to send to repos. As you enable more permissions, more events become available in the next "Subscribe to events" section later on.

Pull requests: Read-only. To be honest, this might not be necessary.

Organization permissions

No access required.

User permissions

No access required.

Subscribe to events

As stated before this is up to you, but here are the events enabled for loop.bass-lang.org at the time of writing:

• Meta
• Pull request
• Push
• Release

Create the app

When it asks Where can this GitHub App be installed?, pick which option makes sense for you. You can always change it later, so it's probably safest to leave it as Only on this account since it's harder to restrict it once people have installed it.

Finally, click Create GitHub App!

Display Information

Once you've created your app you can set a nice logo! This will show up on status checks and on the app itself.

You can generate a Bass logo in your favorite colors like so:

git clone https://github.com/vito/bass
cd bass/
./docs/scripts/generate-logo docs/ico/base16-<THEME>.svg logo.png

Private keys

Your app needs a private key configured in order to make requests on behalf of users. Click "Generate a private key" to create and download one.

Run bass-loop with GitHub app config

Copy your app ID from the top of the settings page, put your private key somewhere within reach, and run:

bass-loop \
  --github-app-id 12345 \
  --github-app-key app-private-key.pem \
  --github-app-webhook-secret mysecret

These parameters can also be set using env vars. I personally use 1Password and the op CLI like so:

cat > creds.env <<EOF
GITHUB_WEBHOOK_SECRET = op://Bass/webhook-secret/password
GITHUB_APP_PRIVATE_KEY = op://Bass/github-app-private-key/private-key
EOF

eval $(op signin)

op run --no-masking --env-file ./creds.env bass-loop