music-assistant-server

1"""
2go-librespot backend for the Spotify Connect provider.
3
4go-librespot is driven entirely over its local HTTP+WebSocket API: the WebSocket
5``/events`` stream feeds player/session/metadata/volume state into Music Assistant,
6and transport + volume commands are issued via the REST endpoints. Playback control
7works without a configured Spotify *music* provider or the Spotify Web API.
8"""
9
10from __future__ import annotations
11
12import asyncio
13import json
14import os
15from contextlib import suppress
16from functools import partial
17from pathlib import Path
18from typing import TYPE_CHECKING, Any
19
20from music_assistant_models.enums import ContentType
21from music_assistant_models.media_items import AudioFormat
22
23from music_assistant.helpers.process import AsyncProcess
24from music_assistant.helpers.util import (
25    interface_name_for_ip,
26    is_port_in_use,
27    select_free_port,
28)
29from music_assistant.providers.spotify_connect.clients.go_librespot import GoLibrespotClient
30from music_assistant.providers.spotify_connect.helpers import (
31    generate_device_id,
32    get_go_librespot_binary,
33)
34from music_assistant.providers.spotify_connect.models import (
35    BackendEvent,
36    BackendEventType,
37    BackendTrackMetadata,
38)
39
40from .base import SpotifyConnectBackend
41
42if TYPE_CHECKING:
43    import logging
44
45    from music_assistant.mass import MusicAssistant
46    from music_assistant.providers.spotify_connect.models import (
47        AudioChunkReader,
48        BackendEventCallback,
49    )
50
51# go-librespot volume scale; we pin volume_steps to this so the daemon's 0..max
52# volume maps 1:1 to a 0-100 percentage.
53VOLUME_STEPS = 100
54
55# Read size for pulling PCM off the daemon's stdout.
56STREAM_READ_CHUNK = 16384
57
58# Port range the go-librespot API server binds to (loopback only, one per instance).
59API_PORT_RANGE_START = 38800
60API_PORT_RANGE_END = 38900
61
62
63class GoLibrespotBackend(SpotifyConnectBackend):
64    """Spotify Connect backend wrapping a supervised go-librespot daemon."""
65
66    def __init__(
67        self,
68        mass: MusicAssistant,
69        *,
70        instance_id: str,
71        publish_name: str,
72        name: str,
73        logger: logging.Logger,
74        event_callback: BackendEventCallback,
75    ) -> None:
76        """
77        Initialize the backend (cheap; the daemon is launched in ``start``).
78
79        :param mass: The MusicAssistant instance.
80        :param instance_id: The owning provider's instance id; keys the
81            credential/cache dir and the stable Spotify device id.
82        :param publish_name: Device name advertised to the Spotify app.
83        :param name: Display name of the owning provider instance (log messages).
84        :param logger: Logger to use for diagnostics.
85        :param event_callback: Awaited with a normalized BackendEvent for every
86            state change the daemon reports.
87        """
88        self.mass = mass
89        self.logger = logger
90        self.name = name
91        self._instance_id = instance_id
92        self._publish_name = publish_name
93        self._event_callback = event_callback
94        self.cache_dir = os.path.join(self.mass.cache_path, instance_id)
95        self._binary: str | None = None
96        self._api_port: int = 0
97        self._client: GoLibrespotClient | None = None
98        self._stop_called: bool = False
99        self._daemon_task: asyncio.Task[None] | None = None
100        self._events_task: asyncio.Task[None] | None = None
101        self._proc: AsyncProcess | None = None
102        self._restart_error_count = 0
103        # _audio_format is the original Spotify source codec (Ogg Vorbis 320 kbps),
104        # advertised to clients for display. _decoded_audio_format is the raw PCM
105        # go-librespot actually writes to its stdout after decoding — what the
106        # audio reader yields and what the streams controller hands ffmpeg as
107        # the input format. We always emit the source's own format here; MA is
108        # responsible for converting it to whatever each player needs.
109        self._audio_format = AudioFormat(
110            content_type=ContentType.OGG,
111            codec_type=ContentType.VORBIS,
112            sample_rate=44100,
113            bit_depth=16,
114            channels=2,
115            bit_rate=320,
116        )
117        self._decoded_audio_format = AudioFormat(
118            content_type=ContentType.PCM_S16LE,
119            codec_type=ContentType.PCM_S16LE,
120            sample_rate=44100,
121            bit_depth=16,
122            channels=2,
123        )
124
125    @property
126    def audio_format(self) -> AudioFormat:
127        """Return the source audio format (advertised to clients for display)."""
128        return self._audio_format
129
130    @property
131    def decoded_audio_format(self) -> AudioFormat:
132        """Return the decoded PCM format the audio reader actually delivers."""
133        return self._decoded_audio_format
134
135    async def start(self) -> None:
136        """Start the backend and its supervised go-librespot daemon."""
137        self._binary = get_go_librespot_binary()
138        self._api_port = await select_free_port(
139            API_PORT_RANGE_START, API_PORT_RANGE_END, host="127.0.0.1"
140        )
141        self._client = GoLibrespotClient(
142            self.mass, f"http://127.0.0.1:{self._api_port}", self.logger
143        )
144        # Two self-healing supervisors: one keeps the daemon process alive, the
145        # other keeps the events websocket connected (reconnecting across daemon
146        # restarts). The events runner resets the daemon's restart backoff once
147        # the websocket is healthy again.
148        self._daemon_task = self.mass.create_task(self._daemon_runner())
149        self._events_task = self.mass.create_task(self._events_runner())
150
151    async def stop(self) -> None:
152        """Stop the daemon and all supervisor tasks."""
153        self._stop_called = True
154        for task in (self._events_task, self._daemon_task):
155            if task and not task.done():
156                task.cancel()
157                with suppress(asyncio.CancelledError):
158                    await task
159
160    def get_audio_reader(self) -> AudioChunkReader | None:
161        """
162        Return a PCM chunk reader bound to the currently running daemon.
163
164        The reader stays bound to this daemon process: once it exits, the
165        reader returns b"" (clean EOF) even if a restarted daemon is already
166        up. None is returned when no daemon is running.
167        """
168        if (proc := self._proc) is None:
169            return None
170        return partial(proc.read, STREAM_READ_CHUNK)
171
172    async def play(self, uri: str, *, skip_to_uri: str | None = None) -> None:
173        """
174        Start playing a Spotify URI/context, making this device the active one.
175
176        :param uri: Spotify URI (track, album, playlist, ...) — typically a context.
177        :param skip_to_uri: Optional track URI within the context to start at.
178        """
179        assert self._client is not None
180        await self._client.play(uri, skip_to_uri=skip_to_uri)
181
182    async def resume(self) -> None:
183        """Resume playback on the active session."""
184        assert self._client is not None
185        await self._client.resume()
186
187    async def pause(self) -> None:
188        """Pause playback on the active session."""
189        assert self._client is not None
190        await self._client.pause()
191
192    async def next(self) -> None:
193        """Skip to the next track."""
194        assert self._client is not None
195        await self._client.next()
196
197    async def previous(self) -> None:
198        """Skip to the previous track (or rewind the current one)."""
199        assert self._client is not None
200        await self._client.prev()
201
202    async def seek(self, position_ms: int) -> None:
203        """
204        Seek to an absolute position in the current track.
205
206        :param position_ms: Target position in milliseconds.
207        """
208        assert self._client is not None
209        await self._client.seek(position_ms)
210
211    async def set_volume(self, volume: int) -> None:
212        """
213        Set the daemon's playback volume.
214
215        :param volume: Absolute volume as a 0-100 percentage (translated to
216            go-librespot's own volume scale).
217        """
218        assert self._client is not None
219        await self._client.set_volume(round(volume / 100 * VOLUME_STEPS))
220
221    def _write_config(self, source_ip: str | None) -> None:
222        """
223        Write the go-librespot ``config.yml`` for this instance.
224
225        go-librespot reads a YAML config; JSON is valid YAML, so we emit JSON to
226        sidestep an extra dependency and any string-quoting pitfalls (the device
227        name is user-provided). The config dir doubles as the credential/device
228        cache so the Spotify Connect device stays paired across restarts.
229
230        :param source_ip: Local address of the player-facing interface, or None to
231            advertise the Spotify Connect device on all interfaces.
232        """
233        Path(self.cache_dir).mkdir(parents=True, exist_ok=True)
234        config: dict[str, Any] = {
235            "device_name": self._publish_name,
236            "device_type": "speaker",
237            "device_id": generate_device_id(self._instance_id),
238            "bitrate": 320,
239            "audio_backend": "pipe",
240            # write decoded PCM to the daemon's stdout, which we capture and
241            # forward (the process pipe is always attached, so the daemon's
242            # non-blocking pipe open never fails for lack of a reader). s16le is
243            # the Spotify source representation; MA converts it per player.
244            "audio_output_pipe": "/dev/stdout",
245            "audio_output_pipe_format": "s16le",
246            # external_volume: don't let go-librespot attenuate the PCM — MA / the
247            # target player owns the actual volume. We still receive 'volume'
248            # events and push volume back so the Spotify app slider stays in sync.
249            # No initial_volume: go-librespot ignores it with external_volume set;
250            # the provider pushes the player's volume instead.
251            "external_volume": True,
252            "volume_steps": VOLUME_STEPS,
253            "zeroconf_enabled": True,
254            "credentials": {"type": "zeroconf", "zeroconf": {"persist_credentials": True}},
255            "server": {"enabled": True, "address": "127.0.0.1", "port": self._api_port},
256        }
257        # Advertise the Spotify Connect device only on the interface the streams
258        # server binds to, so it lands on the right network on multi-homed hosts.
259        # go-librespot selects advertise interfaces by name, so map the IP to one.
260        if source_ip:
261            if iface_name := interface_name_for_ip(source_ip):
262                config["zeroconf_interfaces_to_advertise"] = [iface_name]
263            else:
264                self.logger.debug(
265                    "No interface found for stream bind IP %s; advertising on all interfaces",
266                    source_ip,
267                )
268        config_file = os.path.join(self.cache_dir, "config.yml")
269        with open(config_file, "w", encoding="utf-8") as fileobj:
270            json.dump(config, fileobj, indent=2)
271
272    async def _daemon_runner(self) -> None:
273        """Run and supervise the go-librespot daemon, restarting it if it exits."""
274        assert self._binary
275        assert self._client
276        # Loop forever; stop() cancels this task and the explicit stop-check below
277        # handles a graceful exit without a restart.
278        while True:
279            # If the API port was taken while the daemon was down, move to a
280            # fresh port instead of crash-looping on a bind error.
281            if await is_port_in_use(self._api_port, host="127.0.0.1"):
282                self._api_port = await select_free_port(
283                    API_PORT_RANGE_START, API_PORT_RANGE_END, host="127.0.0.1"
284                )
285                self._client.base_url = f"http://127.0.0.1:{self._api_port}"
286                self.logger.warning(
287                    "API port in use by another process; switching to port %s", self._api_port
288                )
289            self._write_config(await self.mass.streams.get_source_ip())
290            proc: AsyncProcess | None = None
291            try:
292                # stdout carries the decoded PCM (audio_output_pipe=/dev/stdout) and
293                # is consumed through get_audio_reader; stderr carries the daemon's
294                # logs, read here. Because the process pipe owns stdout from spawn
295                # there is always a reader, so go-librespot's non-blocking pipe open
296                # never fails for lack of a consumer.
297                self._proc = proc = AsyncProcess(
298                    [self._binary, "--config_dir", self.cache_dir],
299                    stdout=True,
300                    stderr=True,
301                    name=f"go-librespot[{self.name}]",
302                )
303                await proc.start()
304                self.logger.info("Started Spotify Connect background daemon [%s]", self.name)
305                async for line in proc.iter_stderr():
306                    self.logger.debug("[%s] %s", self.name, line)
307            except asyncio.CancelledError:
308                raise
309            except Exception as err:
310                self.logger.warning("go-librespot daemon error [%s]: %s", self.name, err)
311            finally:
312                if proc:
313                    await proc.close()
314                # The daemon — and thus the Spotify session — is gone. Tell the
315                # provider so a dead/restarting daemon isn't treated as active and
316                # controllable; a fresh 'active' event re-establishes it on reconnect.
317                self._proc = None
318                try:
319                    await self._event_callback(BackendEvent(BackendEventType.CONNECTION_LOST))
320                except Exception:
321                    # never let a callback error replace a propagating
322                    # cancellation or kill the daemon supervisor
323                    self.logger.exception("Error while handling daemon exit")
324            if self._stop_called:
325                break
326            self.logger.info("Spotify Connect background daemon stopped for %s", self.name)
327            self._restart_error_count += 1
328            if self._restart_error_count >= 5:
329                await self._event_callback(
330                    BackendEvent(
331                        BackendEventType.FATAL_ERROR,
332                        error="go-librespot daemon failed to start multiple times.",
333                    )
334                )
335                return
336            await asyncio.sleep(2)
337
338    async def _events_runner(self) -> None:
339        """Keep the go-librespot events websocket connected, reconnecting as needed."""
340        assert self._client is not None
341        while not self._stop_called:
342            try:
343                if not await self._client.wait_until_ready():
344                    await asyncio.sleep(2)
345                    continue
346                # A live websocket means the daemon is healthy: reset the restart
347                # backoff counter the daemon supervisor uses.
348                self._restart_error_count = 0
349                await self._client.listen_events(self._handle_event)
350            except asyncio.CancelledError:
351                raise
352            except Exception as err:
353                self.logger.debug("go-librespot events websocket dropped: %s", err)
354            if not self._stop_called:
355                await asyncio.sleep(2)
356
357    async def _handle_event(self, event_type: str, data: dict[str, Any]) -> None:
358        """Translate a single go-librespot websocket event and emit it normalized."""
359        self.logger.debug("Received event [%s]: %s %s", self.name, event_type, data)
360        await self._event_callback(self._translate_event(event_type, data))
361
362    def _translate_event(self, event_type: str, data: dict[str, Any]) -> BackendEvent:
363        """Map a raw go-librespot event onto the normalized BackendEvent model."""
364        # Every event carries the latest context/track uris when present, so the
365        # provider can take playback back when the user moves the active device
366        # away in the Spotify app.
367        context_uri: str | None = data.get("context_uri") or None
368        track_uri: str | None = data.get("uri") or None
369        if event_type == "active":
370            return BackendEvent(
371                BackendEventType.SESSION_ACTIVE, context_uri=context_uri, track_uri=track_uri
372            )
373        if event_type == "inactive":
374            return BackendEvent(
375                BackendEventType.SESSION_INACTIVE, context_uri=context_uri, track_uri=track_uri
376            )
377        if event_type == "playing":
378            return BackendEvent(
379                BackendEventType.PLAYING, context_uri=context_uri, track_uri=track_uri
380            )
381        if event_type == "paused":
382            return BackendEvent(
383                BackendEventType.PAUSED, context_uri=context_uri, track_uri=track_uri
384            )
385        if event_type == "stopped":
386            return BackendEvent(
387                BackendEventType.STOPPED, context_uri=context_uri, track_uri=track_uri
388            )
389        if event_type == "metadata":
390            artists = data.get("artist_names") or []
391            duration_ms = data.get("duration")
392            return BackendEvent(
393                BackendEventType.METADATA,
394                context_uri=context_uri,
395                track_uri=track_uri,
396                metadata=BackendTrackMetadata(
397                    track_uri=data.get("uri"),
398                    title=data.get("name") or None,
399                    artist=artists[0] if artists else None,
400                    album=data.get("album_name"),
401                    image_url=data.get("album_cover_url"),
402                    duration=duration_ms // 1000 if duration_ms else None,
403                    position=int(data.get("position", 0)) // 1000,
404                ),
405            )
406        if event_type == "seek":
407            return BackendEvent(
408                BackendEventType.POSITION,
409                context_uri=context_uri,
410                track_uri=track_uri,
411                position=int(data.get("position", 0)) // 1000,
412            )
413        if event_type == "volume" and data.get("value") is not None:
414            # translate the daemon's 0..max scale to a 0-100 percentage
415            max_value = data.get("max") or VOLUME_STEPS
416            return BackendEvent(
417                BackendEventType.VOLUME,
418                context_uri=context_uri,
419                track_uri=track_uri,
420                volume=int(int(data["value"]) / int(max_value) * 100),
421            )
422        return BackendEvent(BackendEventType.OTHER, context_uri=context_uri, track_uri=track_uri)
423