Hacking on Tangled

We highly recommend installing Nix (the package manager) before working on the codebase. The Nix flake provides a lot of helpers to get started and most importantly, builds and dev shells are entirely deterministic.

To set up your dev environment:

nix develop

Non-Nix users can look at the devShell attribute in the flake.nix file to determine necessary dependencies.

Running the appview

The appview requires Redis and OAuth JWKs. Start these first, before launching the appview itself.

# OAuth JWKs should already be set up by the Nix devshell:
echo $TANGLED_OAUTH_CLIENT_SECRET
z42ty4RT1ovnTopY8B8ekz9NuziF2CuMkZ7rbRFpAR9jBqMc

echo $TANGLED_OAUTH_CLIENT_KID
1761667908

# if not, you can set it up yourself:
goat key generate -t P-256
Key Type: P-256 / secp256r1 / ES256 private key
Secret Key (Multibase Syntax): save this securely (eg, add to password manager)
        z42tuPDKRfM2mz2Kv953ARen2jmrPA8S9LX9tRq4RVcUMwwL
Public Key (DID Key Syntax): share or publish this (eg, in DID document)
        did:key:zDnaeUBxtG6Xuv3ATJE4GaWeyXM3jyamJsZw3bSPpxx4bNXDR

# the secret key from above
export TANGLED_OAUTH_CLIENT_SECRET="z42tuP..."

# Run Redis in a new shell to store OAuth sessions
redis-server

The Nix flake exposes a few app attributes (run nix flake show to see a full list of what the flake provides), one of the apps runs the appview with the air live-reloader:

TANGLED_DEV=true nix run .#watch-appview

# TANGLED_DB_PATH might be of interest to point to
# different sqlite DBs

# in a separate shell, you can live-reload tailwind
nix run .#watch-tailwind

Running knots and spindles

An end-to-end knot setup requires setting up a machine with sshd, AuthorizedKeysCommand, and a Git user, which is quite cumbersome. So the Nix flake provides a nixosConfiguration to do so.

macOS users will have to set up a Nix Builder first

In order to build Tangled’s dev VM on macOS, you will first need to set up a Linux Nix builder. The recommended way to do so is to run a darwin.linux-builder VM and to register it in nix.conf as a builder for Linux with the same architecture as your Mac (linux-aarch64 if you are using Apple Silicon).

If you’re on nix-darwin, you can simply add

nix.linux-builder.enable = true;

to your host’s configuration.nix.

Alternatively, you can use any other method to set up a Linux machine with Nix installed that you can sudo ssh into (in other words, root user on your Mac has to be able to ssh into the Linux machine without entering a password) and that has the same architecture as your Mac. See remote builder instructions for how to register such a builder in nix.conf.

WARNING: If you’d like to use nixos-lima or Orbstack, note that setting them up so that sudo ssh works can be tricky. It seems to be possible with Orbstack.

To begin, grab your DID from http://localhost:3000/settings. Then, set TANGLED_VM_KNOT_OWNER and TANGLED_VM_SPINDLE_OWNER to your DID. You can now start a lightweight NixOS VM like so:

nix run --impure .#vm

# type `poweroff` at the shell to exit the VM

This starts a knot on port 6444, a spindle on port 6555 with ssh exposed on port 2222.

Once the services are running, head to http://localhost:3000/settings/knots and hit “Verify”. It should verify the ownership of the services instantly if everything went smoothly.

You can push repositories to this VM with this ssh config block on your main machine:

Host nixos-shell
    Hostname localhost
    Port 2222
    User git
    IdentityFile ~/.ssh/my_tangled_key

Set up a remote called local-dev on a git repo:

git remote add local-dev git@nixos-shell:user/repo
git push local-dev main

The above VM should already be running a spindle on localhost:6555. Head to http://localhost:3000/settings/spindles and hit “Verify”. You can then configure each repository to use this spindle and run CI jobs.

Of interest when debugging spindles:

# Service logs from journald:
journalctl -xeu spindle

# CI job logs from disk:
ls /var/log/spindle

# Debugging spindle database:
sqlite3 /var/lib/spindle/spindle.db

# litecli has a nicer REPL interface:
litecli /var/lib/spindle/spindle.db

If for any reason you wish to disable either one of the services in the VM, modify nix/vm.nix and set services.tangled.spindle.enable (or services.tangled.knot.enable) to false.