central-proxy

The shared edge reverse proxy for the DigitalOcean droplet (174.138.36.232). A single Caddy container terminates TLS for every site on the box and routes each hostname to the right upstream container. It is the only thing published on ports 80 and 443; all the application stacks (bigode, nazareonline, ...) sit behind it on the external proxy_net Docker network and speak plain HTTP to it.

Caddy manages Let's Encrypt certificates automatically - it obtains and renews a cert for each hostname listed in the Caddyfile on first request. Issued certs and ACME account keys persist in the caddy_data Docker volume (mounted at /data), not in this repo.

Layout

compose.yaml   the Caddy service: publishes 80/443, joins proxy_net,
               bind-mounts the Caddyfile, persists certs in caddy_data
Caddyfile      one site block per app; each reverse_proxies to a container
               reachable by name on proxy_net
syncthing/     the Syncthing stack (own compose file); GUI behind Caddy,
               sync protocol published on 22000

Prerequisites

• The external network exists: docker network create proxy_net.
• Each upstream stack attaches its public-facing container to proxy_net, so Caddy can reach it by container name (e.g. nazareonline-web-1:80).
• DNS A records for every hostname in the Caddyfile point at the droplet.

Adding a site

Add a block to the Caddyfile naming the hostname(s) and the upstream:

www.example.com, example.com {
    reverse_proxy example-web-1:80
}

The upstream container must be on proxy_net. Caddy forwards the original Host and sets X-Forwarded-Proto: https, so upstreams behind it can rebuild HTTPS URLs and do their own host canonicalisation.

Then reload without downtime (does not disturb the other sites):

docker exec central-proxy-caddy-1 caddy reload --config /etc/caddy/Caddyfile

Validate a change before reloading:

docker run --rm -v "$PWD/Caddyfile":/etc/caddy/Caddyfile:ro caddy:2-alpine \
  caddy validate --config /etc/caddy/Caddyfile

Deploy

The compose stack lives at /home/waldson/central-proxy on the droplet. To apply a change, copy the edited Caddyfile up and reload:

scp -i ~/.ssh/deploy_key ./Caddyfile waldson@174.138.36.232:/home/waldson/central-proxy/Caddyfile
ssh -i ~/.ssh/deploy_key waldson@174.138.36.232 \
  'docker exec central-proxy-caddy-1 caddy reload --config /etc/caddy/Caddyfile'

Bring the proxy up (or recreate it after a compose change) from that directory:

docker compose up -d

Syncthing stack

An always-on Syncthing peer for the owner's folders, giving devices somewhere to sync when no two of them are online together and keeping an off-site copy on the droplet. It lives in syncthing/ and deploys to /home/waldson/central-proxy/syncthing on the droplet.

Only the sync protocol is published on the host (22000/tcp and 22000/udp), so devices connect directly instead of through community relays. The web GUI (8384) is not published; it is reached only through Caddy at sync.waldson.com.br, guarded by Syncthing's own username/password. The central Caddyfile already carries the sync.waldson.com.br block. Binding the GUI to a non-loopback address (STGUIADDRESS=0.0.0.0:8384, required so Caddy in its own container can reach it) also turns off Syncthing's DNS-rebinding host check, so a plain reverse_proxy needs no Host-header rewrite.

Where data lives

Config (device keys, the folder list) and every synced folder live under the host bind mount syncthing/data (mounted at /var/syncthing in the container), so state survives container recreation and is inspectable over plain SSH. The directory is git-ignored. PUID/PGID default to 1000; if the droplet's deploy user has a different id, adjust them in compose.yaml so the synced files stay owned by that user.

Deploy

From syncthing/ on the droplet:

docker compose up -d

The container comes up as syncthing-syncthing-1 on proxy_net, which is the name Caddy reverse-proxies to. A restart preserves config and pairings:

docker compose restart

Upgrade

The image is syncthing/syncthing:latest (Syncthing publishes no rolling major tag; pin a specific version here if you want reproducible upgrades). To update:

docker compose pull && docker compose up -d

First-run setup (interactive, in the GUI)

These steps are done once by the owner at https://sync.waldson.com.br:

1. Set the GUI username and password (Actions -> Settings -> GUI).
2. Add the droplet as a device on each personal device (and vice versa), using the device IDs shown under Actions -> Show ID.
3. Share all five folders (Sync, phone-photos, comprovantes, notes, torque-data) with the droplet and accept them on the droplet, pointing each folder path under /var/syncthing so the data lands in the bind mount.

Droplet groundwork

Baseline host configuration for the droplet (wloud, 174.138.36.232, 2 GB RAM, 2 vCPUs, 58 GB disk). Everything below was set up once and only needs revisiting when the host changes.

Swap

The droplet has 2 GB RAM and no swap by default; a 2 GB swapfile prevents Out Of Memory (OOM) kills during on-droplet builds and daemon memory spikes. It is created once with (requires sudo):

sudo fallocate -l 2G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
echo 'vm.swappiness=10' | sudo tee /etc/sysctl.d/99-swappiness.conf
sudo sysctl -p /etc/sysctl.d/99-swappiness.conf

The fstab entry makes it survive reboots; swappiness 10 keeps the kernel from swapping eagerly. Verify with free -m (~2048 total swap) and, after a reboot, swapon --show.

Firewall

ufw is installed and active on the host. Probing from outside the droplet (2026-07-23) showed no filtering in the path for the service ports: 2222/tcp and 22000/tcp answered "connection refused" while nothing listened, which means packets reach the host, so neither ufw nor a DigitalOcean cloud firewall blocks them. Ports in use:

Port	Proto	Service
22	tcp	host sshd
80, 443	tcp	Caddy (all HTTP/HTTPS traffic)
2222	tcp	Forgejo git-over-SSH
22000	tcp+udp	Syncthing sync protocol

If ufw rules are ever tightened, keep the four rows above allowed. To re-verify reachability from any machine outside the droplet:

nc -vz 174.138.36.232 2222
nc -vz 174.138.36.232 22000
nc -vzu 174.138.36.232 22000

"Connection refused" means the port is reachable but nothing listens yet; only a timeout indicates a filter.

DNS

All records live on the DigitalOcean nameservers (ns1-3.digitalocean.com) and point at the droplet:

Record	Type	Value	Serves
waldson.com.br	A	174.138.36.232	personal site
www.waldson.com.br	A	174.138.36.232	redirect to apex
git.waldson.com.br	A	174.138.36.232	Forgejo
sync.waldson.com.br	A	174.138.36.232	Syncthing GUI

personaledson.com.br and nazareonline.com.br also resolve here for the existing stacks. Check resolution with:

dig +short waldson.com.br www.waldson.com.br git.waldson.com.br sync.waldson.com.br

Notes

• letsencrypt/acme.json is leftover state from an earlier Traefik-based proxy and is not used by Caddy. It is git-ignored (it contains private keys); it can be deleted from the droplet once you are sure nothing references it.
• Never docker volume rm caddy_data - that discards every issued certificate and forces re-issuance, which can hit Let's Encrypt rate limits.