RTL/docker

RTL regtest dev fixture

NOT suitable for production. Development only. Every credential here is throwaway.

A self-contained regtest network for developing and testing RTL: bitcoind, three LND nodes, a Core Lightning node, and RTL wired to all four.

alice --[ 5,000,000 sat ]--> bob --[ 3,000,000 sat ]--> carol
cln   --[ 4,000,000 sat ]--> alice

bob sits in the middle so it accrues forwarding history, which is what gives RTL's routing screens something to show. Two nodes would leave them empty. The cln (Core Lightning) node gives RTL's CLN screens a real backend — it talks to RTL over clnrest with rune auth.

LND and bitcoind images come from Polar; the Core Lightning image is the official elementsproject/lightningd. All are multi-arch (amd64 + arm64) and nothing is built locally, so this works on Apple Silicon.

Requirements

Docker with Compose v2 (docker compose, not docker-compose).

Quick start

From this directory:

docker compose up -d          # bitcoind, alice, bob, carol, cln, rtl
./scripts/seed.sh             # fund, connect, open channels, make payments

Then open http://localhost:3000 — password rtldev. All four nodes (alice, bob, carol, cln) appear in the node switcher.

Tear down, discarding all state:

docker compose down -v

What the seed creates

On-chain	10,000,000 sats per node (LND) + 10,000,000 sats on cln, confirmed
Channels	alice→bob 5,000,000 sats · bob→carol 3,000,000 sats (1,000,000 pushed each) · cln→alice 4,000,000 sats
Routed payments	5 × alice→carol via bob (10k, 25k, 50k, 75k, 100k sats)
Direct payments	2 × alice→bob (5k, 15k sats)
Open invoices	2 unpaid on carol (20k, 40k sats)
Personas	alice + bob + cln OPERATOR, carol MERCHANT

Determinism

Every amount and payment in scripts/seed.sh is fixed. A fresh run always produces identical state, so screenshots taken before and after a change differ only by the change. Do not introduce randomness.

The seed is deterministic but deliberately not idempotent — running it twice would fund every node again and open a second set of channels. It refuses to run against an already-seeded network. To start over:

docker compose down -v && docker compose up -d && ./scripts/seed.sh

Helpers

bin/b-cli getblockcount                    # bitcoin-cli
bin/b-cli -rpcwallet=rtldev getbalance
bin/ln-cli alice getinfo                   # lncli, node name required
bin/ln-cli bob listchannels
bin/ln-cli bob fwdinghistory               # forwarding history
docker compose exec cln lightning-cli --network=regtest listpeerchannels   # Core Lightning

Logs:

docker compose logs -f rtl
docker compose logs alice

Notes and gotchas

RTL's config. rtl/RTL-Config.regtest.json is the tracked template. RTL rewrites its config on startup, so an init container copies it into a volume rather than bind-mounting it — a read-only mount makes RTL exit with EROFS, and a writable one would let RTL modify a version-controlled file. The name is not RTL-Config.json because .gitignore matches that bare filename at any depth.

lncli needs --lnddir=/home/lnd/.lnd. docker compose exec lands as root, whose HOME is /root, but lnd's datadir is /home/lnd/.lnd. bin/ln-cli handles this.

Changing bitcoind credentials. docker-compose.yml carries an -rpcauth hash for the BITCOIN_RPC_USER / BITCOIN_RPC_PASSWORD in .env. Changing them there is not enough; regenerate the hash:

python3 - <<'EOF'
import hmac, hashlib
user, password, salt = "rtldev", "rtldev", "8a1f2c3d4e5b6a7c8d9e0f1a2b3c4d5e"
print(f"{user}:{salt}${hmac.new(salt.encode(), password.encode(), hashlib.sha256).hexdigest()}")
EOF

In docker-compose.yml the $ must be written $$ to escape Compose interpolation.

Payments right after channel open will fail. The channel graph has to reach alice before she can route to carol. The seed waits for this; anything you script yourself should too.

Core Lightning auth uses a rune. RTL talks to cln over clnrest and authenticates with a rune, not a macaroon. cln/create-rune.sh — run from the cln healthcheck — creates a master rune once the RPC is up and writes it as LIGHTNING_RUNE="…" to rtl.rune in the shared cln_data volume; RTL reads it via the runePath in its config. The healthcheck reports unhealthy until that file exists, so RTL (which waits on service_healthy) starts only once the rune is ready. Because it runs on every healthcheck tick (idempotent), a transient RPC-startup race just retries and self-heals rather than wedging the stack. --clnrest-host=0.0.0.0 is required for RTL (another container) to reach clnrest; the default 127.0.0.1 would only be reachable from inside the node.

Not included

Eclair nodes and the Boltz swap service. Polar publishes a multi-arch eclair image, so adding an Eclair node means a compose service, an RTL config entry, and a seeding adapter — no image building.