# DChain production deployment

Turn-key-ish stack: 3 validators + Caddy TLS edge + optional
Prometheus/Grafana, behind auto-HTTPS.

## Prerequisites

- Docker + Compose v2
- A public IP and open ports `80`, `443`, `4001` (libp2p) on every host
- DNS `A`-record pointing `DOMAIN` at the host running Caddy
- Basic familiarity with editing env files

## Layout (single-host pilot)

```
                   ┌─ Caddy :443 ── TLS terminate ──┬─ node1:8080 ──┐
 internet ────────→│                                ├─ node2:8080  │ round-robin /api/*
                   └─ Caddy :4001 (passthrough)     └─ node3:8080  │ ip_hash /api/ws
                   ...
                   Prometheus → node{1,2,3}:8080/metrics
                   Grafana ← Prometheus data source
```

For a real multi-datacentre deployment, copy this whole directory onto each
VPS, edit `docker-compose.yml` to keep only the node that runs there, and
put Caddy on one dedicated edge host (or none — point clients at one node
directly and accept the lower availability).

## First-boot procedure

1. **Generate keys** for each validator. Easiest way:

   ```bash
   # On any box with the repo checked out
   docker build -t dchain-node-slim -f deploy/prod/Dockerfile.slim .
   mkdir -p deploy/prod/keys
   for i in 1 2 3; do
     docker run --rm -v "$PWD/deploy/prod/keys:/out" dchain-node-slim \
       /usr/local/bin/client keygen --out /out/node$i.json
   done
   cat deploy/prod/keys/node*.json | jq -r .pub_key  # → copy into DCHAIN_VALIDATORS
   ```

2. **Configure env files**. Copy `node.env.example` to `node1.env`,
   `node2.env`, `node3.env`. Paste the three pubkeys from step 1 into
   `DCHAIN_VALIDATORS` in ALL THREE files. Set `DOMAIN` to your public host.

3. **Start the network**:

   ```bash
   DOMAIN=dchain.example.com docker compose up -d
   docker compose logs -f node1   # watch genesis + first blocks
   ```

   First block is genesis (index 0), created only by `node1` because it has
   the `--genesis` flag. After you see blocks #1, #2, #3… committing,
   **edit `docker-compose.yml` and remove the `--genesis` flag from node1's
   command section**, then `docker compose up -d node1` to re-create it
   without that flag. Leaving `--genesis` in makes no-op on a non-empty DB
   but is noise in the logs.

4. **Verify HTTPS** and HTTP-to-HTTPS redirect:

   ```bash
   curl -s https://$DOMAIN/api/netstats | jq
   curl -s https://$DOMAIN/api/well-known-contracts | jq
   ```

   Caddy should have issued a cert automatically from Let's Encrypt.

5. **(Optional) observability**:

   ```bash
   GRAFANA_ADMIN_PW=$(openssl rand -hex 24) docker compose --profile monitor up -d
   # Grafana at http://<host>:3000, user admin, password from env
   ```

   Add a "Prometheus" data source pointing at `http://prometheus:9090`,
   then import a dashboard that graphs:
   - `dchain_blocks_total` (rate)
   - `dchain_tx_submit_accepted_total` / `rejected_total`
   - `dchain_ws_connections`
   - `dchain_peer_count_live`
   - `rate(dchain_block_commit_seconds_sum[5m]) / rate(dchain_block_commit_seconds_count[5m])`

## Common tasks

### Add a 4th validator

The new node joins as an observer via `--join`, then an existing validator
promotes it on-chain:

```bash
# On the new box
docker run -d --name node4 \
  --volumes chaindata:/data \
  -e DCHAIN_ANNOUNCE=/ip4/<public-ip>/tcp/4001 \
  dchain-node-slim \
  --db=/data/chain --join=https://$DOMAIN --register-relay
```

Then from any existing validator:

```bash
docker compose exec node1 /usr/local/bin/client add-validator \
  --key /keys/node.json \
  --node http://localhost:8080 \
  --target <NEW_PUBKEY>
```

The new node starts signing as soon as it sees itself in the validator set
on-chain — no restart needed.

### Upgrade without downtime

PBFT tolerates `f` faulty nodes out of `3f+1`. For 3 validators that means
**zero** — any offline node halts consensus. So for 3-node clusters:

1. `docker compose pull && docker compose build` on all three hosts first.
2. Graceful one-at-a-time: `docker compose up -d --no-deps node1`, wait for
   `/api/netstats` to show it catching up, then do node2, then node3.

For 4+ nodes you can afford one-at-a-time hot rolls.

### Back up the chain

```bash
docker run --rm -v node1_data:/data -v "$PWD":/bak alpine \
  tar czf /bak/dchain-backup-$(date +%F).tar.gz -C /data .
```

Restore by swapping the file back into a fresh named volume before node
startup.

### Remove a bad validator

Same as adding but with `remove-validator`. Only works if a majority of
CURRENT validators cosign the removal — intentional, keeps one rogue
validator from kicking others unilaterally (see ROADMAP P2.1).

## Security notes

- `/metrics` is firewalled to internal networks by Caddy. If you need
  external scraping, add proper auth (Caddy `basicauth` or mTLS).
- All public endpoints are rate-limited per-IP via the node itself — see
  `api_guards.go`. Adjust limits before releasing to the open internet.
- Each node runs as non-root inside a read-only rootfs container with all
  capabilities dropped. If you need to exec into one, `docker compose exec
  --user root nodeN sh`.
- The Ed25519 key files mounted at `/keys/node.json` are your validator
  identities. Losing them means losing your ability to produce blocks; get
  them onto the host via your normal secret-management (Vault, sealed-
  secrets, encrypted tarball at deploy time). **Never commit them to git.**

## Troubleshooting

| Symptom | Check |
|---------|-------|
| Caddy keeps issuing `failed to get certificate` | Is port 80 open? DNS A-record pointing here? `docker compose logs caddy` |
| New node can't sync: `FATAL: genesis hash mismatch` | The `--db` volume has data from a different chain. `docker volume rm nodeN_data` and re-up |
| Chain stops producing blocks | `docker compose logs nodeN \| tail -100`; look for `SLOW AddBlock` or validator silence |
| `/api/ws` returns 429 | Client opened > `WSMaxConnectionsPerIP` (default 10). Check `ws.go` for per-IP cap |
| Disk usage growing | Background vlog GC runs every 5 min. Manual: `docker compose exec nodeN /bin/sh -c 'kill -USR1 1'` (see `StartValueLogGC`) |