chore(backup): archive via SSH tunnel to the relay host (DNS-independent)

backup-relay.sh now tunnels to the relay host's 127.0.0.1:7777 (ssh alias skatespots-cvm, override SKATESPOTS_RELAY_SSH) and falls back to the public URL, so the weekly archive no longer depends on public DNS. Verified: 115 events archived + restic push.

AGENTS.md

@@ -2114,8 +2114,14 @@ The community relay moved off the hosted relay.tools instance
 - ⚠️ `relay.skate-spots.org` can show a stale NXDOMAIN in a local resolver cache
   right after creation (our dev box did). Verify with
   `curl --resolve relay.skate-spots.org:443:185.18.221.2 …` or from another host.
-- **Backups:** `scripts/archive-relay.mjs` now defaults to the new relay; the
-  weekly timer + restic offsite are unchanged.
+- **Backups:** the weekly `skatespots-archive.timer` still runs
+  `scripts/backup-relay.sh`, but it now archives **through an SSH tunnel** to the
+  relay host's `127.0.0.1:7777` (overridable via `SKATESPOTS_RELAY_SSH`; falls back
+  to the public URL if the tunnel can't be established), so it never depends on
+  public DNS resolving from the dev box. Local snapshots stay in
+  `~/.backups/relay` (12 kept) and restic pushes to the host's repo
+  (`~/.config/skatespots/restic.env`). Two locations today (relay host + dev box);
+  a third would need a new offsite destination.
 
 ### Git / ngit publishing
 - Push: `git push origin main` (handled by `git-remote-nostr`; publishes a signed repo-state event).

scripts/backup-relay.sh

@@ -5,9 +5,15 @@
 # Driven by the systemd user timer `skatespots-archive.timer` (install with
 # scripts/install-archive-timer.sh). Local archives land in
 # ~/.backups/relay; if ~/.config/skatespots/restic.env exists, the whole
-# directory is pushed to a restic repository (S3/R2/B2/SFTP) and old snapshots
-# are pruned. Without that file the archive is local-only — still useful, but
-# not a real offsite backup.
+# directory is pushed to a restic repository (SFTP to our own host, or any
+# S3/R2/B2 store) and old snapshots are pruned. Without that file the archive is
+# local-only — still useful, but not a real offsite backup.
+#
+# The relay lives on OUR host. The archive reaches it over an SSH tunnel to that
+# host's 127.0.0.1:7777 (so it never depends on public DNS resolving from this
+# machine). If the tunnel can't be established it falls back to the public URL.
+# Override with SKATESPOTS_RELAY_SSH (default: the `skatespots-cvm` ssh alias)
+# and SKATESPOTS_RELAY_TUNNEL_PORT (default 17777).
 #
 # Manual run / debug:
 #   scripts/backup-relay.sh
@@ -24,13 +30,39 @@ RESTIC_ENV="$HOME/.config/skatespots/restic.env"
 # CVM host + object storage. Same format as restic.env.
 RESTIC_ENV_2="$HOME/.config/skatespots/restic-2.env"
 
+TUNNEL_PORT="${SKATESPOTS_RELAY_TUNNEL_PORT:-17777}"
+SSH_TARGET="${SKATESPOTS_RELAY_SSH:-skatespots-cvm}"
+
 log() { echo "[$(date -Is)] $*"; }
 
 mkdir -p "$ARCHIVE_DIR"
 cd "$REPO"
 
+# Port-open probe (uses node, which is always on PATH here).
+port_open() {
+  node -e 'const n=require("net");const s=n.connect(+process.argv[1],"127.0.0.1");s.on("connect",()=>{s.destroy();process.exit(0)});s.on("error",()=>process.exit(1));setTimeout(()=>process.exit(1),2000)' "$1" 2>/dev/null
+}
+
 log "archiving the community relay…"
-node scripts/archive-relay.mjs
+RELAY_ARG=""
+TUNNEL_PID=""
+ssh -N -o BatchMode=yes -o ExitOnForwardFailure=yes \
+  -L "127.0.0.1:${TUNNEL_PORT}:127.0.0.1:7777" "$SSH_TARGET" >/dev/null 2>&1 &
+TUNNEL_PID=$!
+trap 'kill "$TUNNEL_PID" 2>/dev/null || true' EXIT
+for _ in 1 2 3 4 5; do
+  port_open "$TUNNEL_PORT" && break
+  sleep 1
+done
+if port_open "$TUNNEL_PORT"; then
+  RELAY_ARG="--relay ws://127.0.0.1:${TUNNEL_PORT}"
+  log "  via SSH tunnel to $SSH_TARGET (localhost:7777)"
+else
+  log "  tunnel unavailable — using the public relay URL"
+fi
+
+# shellcheck disable=SC2086
+node scripts/archive-relay.mjs $RELAY_ARG
 
 # Push the archive directory to every configured restic repo. Each is sourced in
 # its own subshell so RESTIC_* variables don't leak between destinations.