Bake cross-service port collision avoidance into every service script
With 70+ services sharing a handful of common default ports (emby and jellyfin both default to 8096, changedetection and frigate both default to 5000, arm and nextcloud both default to 8080...), nothing previously checked whether a service's default port was actually free on the host. Whichever service installed second would silently write a compose file claiming an already-held port, only failing at `docker compose up` time. Adds two shared helpers to lib/common.sh: - port_in_use PORT [PROTO] — true if something's already listening - find_free_port VARNAME START [PROTO] — scans upward, writes back the first free port Every service that publishes a fixed host port now scans before writing docker-compose.yml, on every install (not just when adding an explicit additional instance). On a normal single-install host this is a silent no-op; it only changes behavior when something else already holds the port. - The 19 services already given multi-instance support this session had their port scan moved out of the "add instance" branch to run unconditionally, since the same collision risk exists on a plain first install. - 20 more services with previously-hardcoded ports gained scanning for the first time: archivebox, arm, calibre-web, changedetection, drum-rhythm-game, gatus, n8n, nextcloud, onlyoffice, stirling-pdf, uptimekuma, portainer, iopaint (both GPU/CPU compose branches), koha (paired), syncthing (paired), wg-easy (paired, plus WG_PORT env so generated peer configs keep the right Endpoint), homeassistant (bridge-mode only — host mode can only warn), frigate and frigate-audio (multi-port stacks, moved together). - caddy.sh is the deliberate exception: 80/443 stay fixed and only warn on collision, since silently moving Caddy itself would leave nothing listening where any client actually looks. - authelia.sh needs no change — it has no published host port at all. - Every service's standalone bootstrap fallback (sudo bash services/x.sh with no sibling files) got the same two helpers duplicated into its stub block, matching how every other shared helper is already handled there. Documents the full pattern in CLAUDE.md's new "Port collision avoidance" section, including the quoted-heredoc/backtick-escaping gotcha and the network_mode:host limitation (can only scan ports the app takes as a configurable env var). Verified via bash -n on every changed file, plus functional runs seeding occupied ports for each collision shape used here (single, paired, multi-port stacks) and confirming the scan/shift and generated compose/README output are correct — including the emby/jellyfin, nextcloud/arm, and frigate/changedetection collision scenarios that originally motivated this.
This commit is contained in:
Claude
+44
-9
@@ -41,6 +41,21 @@ if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
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chown -R "$ACTUAL_USER:$ACTUAL_USER" "$@" 2>/dev/null || true
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}
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port_in_use() {
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local _port="$1" _proto="${2:-tcp}"
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local _flag="-tlnH"
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[ "$_proto" = "udp" ] && _flag="-ulnH"
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ss "$_flag" "sport = :${_port}" 2>/dev/null | grep -q .
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}
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find_free_port() {
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local _varname="$1" _port="$2" _proto="${3:-tcp}"
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while port_in_use "$_port" "$_proto"; do
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_port=$((_port + 1))
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done
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eval "$_varname='$_port'"
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}
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# Match common.sh's eval-based pattern so local vars in install_* are set correctly
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prompt_text() {
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local _q="$1" _def="$2" _var="$3" _r
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@@ -157,13 +172,28 @@ install_syncthing() {
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log_info "Installing Syncthing..."
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local DIR="$DOCKER_DIR/syncthing"
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local WEB_PORT="8384" SYNC_PORT="22000" DISCOVERY_PORT="21027"
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if [ "$DRY_RUN" = true ]; then
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echo "[DRY-RUN] Would create $DIR with docker-compose.yml and .env"
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echo "[DRY-RUN] Would expose web UI on 8384, sync protocol on 22000 (tcp+udp), discovery on 21027/udp"
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echo "[DRY-RUN] All 3 auto-scanned/shifted together if occupied"
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return 0
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fi
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# Scan for free host ports, moving all 3 together — a plain install
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# shouldn't silently claim a port another already-running service holds.
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# Note: DISCOVERY_PORT (LAN broadcast) only works for zero-config local
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# discovery at its standard number — shifting it away from 21027 means
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# peers must be added manually by device ID instead of relying on
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# auto-discovery. See CLAUDE.md's "Port collision avoidance" section.
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while port_in_use "$WEB_PORT" || port_in_use "$SYNC_PORT" \
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|| port_in_use "$SYNC_PORT" udp || port_in_use "$DISCOVERY_PORT" udp; do
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WEB_PORT=$((WEB_PORT + 1))
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SYNC_PORT=$((SYNC_PORT + 1))
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DISCOVERY_PORT=$((DISCOVERY_PORT + 1))
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done
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mkdir -p "$DIR"
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ensure_docker_dir_ownership "$DIR"
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cd "$DIR" || return 1
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@@ -209,10 +239,10 @@ services:
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- PGID=\${PGID:-$PGID}
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- TZ=\${SITE_TZ:-UTC}
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ports:
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- "8384:8384"
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- "22000:22000/tcp"
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- "22000:22000/udp"
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- "21027:21027/udp"
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- "${WEB_PORT}:8384"
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- "${SYNC_PORT}:22000/tcp"
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- "${SYNC_PORT}:22000/udp"
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- "${DISCOVERY_PORT}:21027/udp"
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volumes:
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- ./config:/var/syncthing/config
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- ./data:/var/syncthing
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@@ -237,15 +267,20 @@ ENV
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Continuous, decentralised file synchronisation between devices.
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## Access
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- Web UI: http://localhost:8384
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- Web UI: http://localhost:${WEB_PORT}
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- First run: go to **Settings → GUI** and set a username and password.
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$( [ "$DISCOVERY_PORT" != "21027" ] && echo "
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**Note:** the default ports were already in use, so this instance's ports
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were shifted — see below. Local LAN auto-discovery only works at the
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standard 21027/udp; with a shifted discovery port, add other devices
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manually by device ID instead of relying on auto-discovery." )
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## Firewall ports (for LAN sync)
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Open these on the host firewall so other Syncthing devices can reach this node:
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\`\`\`
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sudo ufw allow 22000/tcp comment "Syncthing sync protocol"
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sudo ufw allow 22000/udp comment "Syncthing sync protocol (QUIC)"
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sudo ufw allow 21027/udp comment "Syncthing local discovery"
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sudo ufw allow ${SYNC_PORT}/tcp comment "Syncthing sync protocol"
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sudo ufw allow ${SYNC_PORT}/udp comment "Syncthing sync protocol (QUIC)"
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sudo ufw allow ${DISCOVERY_PORT}/udp comment "Syncthing local discovery"
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\`\`\`
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## Manage
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@@ -266,7 +301,7 @@ MD
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|| log_warning "Start failed — check: docker compose logs"
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fi
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echo " Access at: http://localhost:8384"
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echo " Access at: http://localhost:${WEB_PORT}"
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echo " First run: set a username and password in Settings → GUI"
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echo ""
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}
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