Add automatic hotspot if a known SSID is not available

docker-compose.yml

@@ -61,6 +61,28 @@ services:
       - ROS_DOMAIN_ID=${ROS_DOMAIN_ID:-0}
     restart: unless-stopped
 
+  wifi:
+    build:
+      context: wifi
+      dockerfile: Dockerfile
+      platforms:
+        - linux/arm64
+    image: raspbot_v2_wifi:latest
+    network_mode: host
+    cap_add:
+      - NET_ADMIN
+    volumes:
+      - /run/dbus/system_bus_socket:/run/dbus/system_bus_socket
+    environment:
+      - WIFI_SSID=${WIFI_SSID:-}
+      - HOTSPOT_SSID=${HOTSPOT_SSID:-raspbot-hotspot}
+      - HOTSPOT_PASSWORD=${HOTSPOT_PASSWORD:-raspbot1234}
+      - HOTSPOT_BAND=${HOTSPOT_BAND:-bg}
+      - WIFI_IFACE=${WIFI_IFACE:-}
+      - WIFI_TIMEOUT=${WIFI_TIMEOUT:-30}
+      - POLL_INTERVAL=${POLL_INTERVAL:-15}
+    restart: unless-stopped
+
   webui:
     build:
       context: webui

wifi/Dockerfile

@@ -0,0 +1,19 @@
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        network-manager \
+        python3 \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY wifi_manager.py .
+
+ENV WIFI_SSID=""
+ENV HOTSPOT_SSID="raspbot-hotspot"
+ENV HOTSPOT_PASSWORD="raspbot1234"
+ENV HOTSPOT_BAND="bg"
+ENV WIFI_IFACE=""
+ENV WIFI_TIMEOUT="30"
+ENV POLL_INTERVAL="15"
+
+CMD ["python3", "wifi_manager.py"]

wifi/wifi_manager.py

@@ -0,0 +1,204 @@
+#!/usr/bin/env python3
+"""
+WiFi hotspot fallback manager.
+
+Monitors whether the robot is connected to a known SSID.  If the SSID is not
+seen within WIFI_TIMEOUT seconds of startup, or if the connection is later
+lost, it creates a NetworkManager WiFi hotspot so the robot remains reachable.
+When the target SSID becomes visible again the hotspot is torn down and the
+robot reconnects.
+
+Communicates with the host NetworkManager via nmcli (the host D-Bus socket is
+bind-mounted into the container).
+"""
+import os
+import subprocess
+import time
+import logging
+
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s  %(levelname)-7s  %(message)s',
+    datefmt='%H:%M:%S',
+)
+log = logging.getLogger('wifi_manager')
+
+WIFI_SSID       = os.environ.get('WIFI_SSID', '')
+HOTSPOT_SSID    = os.environ.get('HOTSPOT_SSID', 'raspbot-hotspot')
+HOTSPOT_PASSWORD = os.environ.get('HOTSPOT_PASSWORD', 'raspbot1234')
+HOTSPOT_BAND    = os.environ.get('HOTSPOT_BAND', 'bg')   # bg=2.4 GHz, a=5 GHz
+WIFI_IFACE      = os.environ.get('WIFI_IFACE', '')        # auto-detect if empty
+WIFI_TIMEOUT    = int(os.environ.get('WIFI_TIMEOUT', '30'))
+POLL_INTERVAL   = int(os.environ.get('POLL_INTERVAL', '15'))
+HOTSPOT_CON_NAME = 'raspbot-hotspot'
+
+
+def _run(cmd: list[str], check=False, capture=True) -> subprocess.CompletedProcess:
+    return subprocess.run(
+        cmd,
+        capture_output=capture,
+        text=True,
+        check=check,
+    )
+
+
+def _nmcli(*args: str, check=False) -> subprocess.CompletedProcess:
+    return _run(['nmcli', '--terse', '--colors', 'no', *args], check=check)
+
+
+def get_wifi_interface() -> str | None:
+    """Return the name of the first WiFi interface NM knows about."""
+    r = _nmcli('-f', 'DEVICE,TYPE', 'device', 'status')
+    for line in r.stdout.splitlines():
+        parts = line.split(':')
+        if len(parts) >= 2 and parts[1] == 'wifi':
+            return parts[0]
+    return None
+
+
+def is_connected_to(ssid: str) -> bool:
+    """Return True if any WiFi connection with this SSID is currently active."""
+    r = _nmcli('-f', 'NAME,TYPE,STATE', 'connection', 'show', '--active')
+    for line in r.stdout.splitlines():
+        parts = line.split(':')
+        if len(parts) >= 3 and parts[2].strip() == 'activated':
+            # Also check active device connection SSID via device status
+            pass
+    # More reliable: check active connection SSID via device
+    r2 = _nmcli('-f', 'ACTIVE-CONNECTION.ID,GENERAL.CONNECTION', 'device', 'show')
+    # Simplest approach: scan active connections for the SSID
+    r3 = _nmcli('-f', 'ACTIVE,SSID', 'device', 'wifi', 'list')
+    for line in r3.stdout.splitlines():
+        parts = line.split(':', 1)
+        if len(parts) == 2 and parts[0].strip() == 'yes' and parts[1].strip() == ssid:
+            return True
+    return False
+
+
+def ssid_visible(ssid: str, iface: str) -> bool:
+    """Return True if the target SSID appears in a WiFi scan."""
+    r = _nmcli('-f', 'SSID', 'device', 'wifi', 'list', 'ifname', iface)
+    for line in r.stdout.splitlines():
+        if line.strip() == ssid:
+            return True
+    return False
+
+
+def hotspot_active() -> bool:
+    """Return True if our hotspot connection is currently active."""
+    r = _nmcli('-f', 'NAME,STATE', 'connection', 'show', '--active')
+    for line in r.stdout.splitlines():
+        parts = line.split(':')
+        if len(parts) >= 2 and parts[0] == HOTSPOT_CON_NAME and 'activated' in parts[1]:
+            return True
+    return False
+
+
+def start_hotspot(iface: str) -> bool:
+    """Bring up a WiFi hotspot on *iface*.  Returns True on success."""
+    # Remove any stale connection profile first
+    _nmcli('connection', 'delete', HOTSPOT_CON_NAME)
+
+    log.info('Starting hotspot SSID=%s on %s', HOTSPOT_SSID, iface)
+    r = _nmcli(
+        'device', 'wifi', 'hotspot',
+        'ifname', iface,
+        'con-name', HOTSPOT_CON_NAME,
+        'ssid', HOTSPOT_SSID,
+        'band', HOTSPOT_BAND,
+        'password', HOTSPOT_PASSWORD,
+    )
+    if r.returncode != 0:
+        log.error('Failed to start hotspot: %s', r.stderr.strip())
+        return False
+    log.info('Hotspot active — SSID=%s  password=%s', HOTSPOT_SSID, HOTSPOT_PASSWORD)
+    return True
+
+
+def stop_hotspot() -> None:
+    """Tear down the hotspot connection profile."""
+    log.info('Stopping hotspot')
+    _nmcli('connection', 'down', HOTSPOT_CON_NAME)
+    _nmcli('connection', 'delete', HOTSPOT_CON_NAME)
+
+
+def connect_to_ssid(ssid: str) -> bool:
+    """Ask NetworkManager to connect to a previously-known SSID."""
+    log.info('Connecting to %s', ssid)
+    r = _nmcli('connection', 'up', 'id', ssid)
+    if r.returncode != 0:
+        # Fall back to device connect (works if there's a saved profile)
+        r2 = _nmcli('device', 'wifi', 'connect', ssid)
+        if r2.returncode != 0:
+            log.warning('Could not reconnect to %s: %s', ssid, r2.stderr.strip())
+            return False
+    return True
+
+
+def wait_for_ssid(ssid: str, iface: str, timeout: int) -> bool:
+    """Poll until *ssid* is connected or *timeout* seconds elapse."""
+    deadline = time.monotonic() + timeout
+    while time.monotonic() < deadline:
+        if is_connected_to(ssid):
+            return True
+        remaining = deadline - time.monotonic()
+        log.info('Waiting for %s (%.0fs remaining)…', ssid, max(remaining, 0))
+        time.sleep(min(POLL_INTERVAL, max(remaining, 1)))
+    return False
+
+
+def main() -> None:
+    if not WIFI_SSID:
+        log.error('WIFI_SSID not set — nothing to do.')
+        return
+
+    iface = WIFI_IFACE or get_wifi_interface()
+    if not iface:
+        log.error('No WiFi interface found via NetworkManager.')
+        return
+    log.info('Using WiFi interface: %s', iface)
+
+    in_hotspot_mode = False
+
+    # ── startup: wait for the target SSID ───────────────────────────────────
+    log.info('Waiting up to %ds for SSID=%s', WIFI_TIMEOUT, WIFI_SSID)
+    if wait_for_ssid(WIFI_SSID, iface, WIFI_TIMEOUT):
+        log.info('Connected to %s', WIFI_SSID)
+    else:
+        log.info('SSID not available — activating hotspot')
+        start_hotspot(iface)
+        in_hotspot_mode = True
+
+    # ── main loop ────────────────────────────────────────────────────────────
+    while True:
+        time.sleep(POLL_INTERVAL)
+
+        if in_hotspot_mode:
+            # Trigger a fresh scan so NM updates the visible-SSIDs list
+            _nmcli('device', 'wifi', 'rescan', 'ifname', iface)
+            time.sleep(3)  # give NM a moment to update scan results
+
+            if ssid_visible(WIFI_SSID, iface):
+                log.info('Target SSID %s visible — switching back', WIFI_SSID)
+                stop_hotspot()
+                in_hotspot_mode = False
+                time.sleep(2)
+                if connect_to_ssid(WIFI_SSID):
+                    log.info('Reconnected to %s', WIFI_SSID)
+                else:
+                    log.warning('Reconnect failed — falling back to hotspot')
+                    start_hotspot(iface)
+                    in_hotspot_mode = True
+        else:
+            if not is_connected_to(WIFI_SSID):
+                log.warning('Lost connection to %s', WIFI_SSID)
+                # Brief retry before giving up
+                time.sleep(5)
+                if not is_connected_to(WIFI_SSID):
+                    log.info('Connection lost — activating hotspot')
+                    start_hotspot(iface)
+                    in_hotspot_mode = True
+
+
+if __name__ == '__main__':
+    main()