unshackle/docs/dev/rest-api/remote-sessions.md

Remote Service Sessions

A remote session lets one machine do the hard, service-specific work (authenticating to a streaming service, listing titles, resolving tracks and manifests, and, optionally, DRM licensing) while another machine runs the actual download, decryption, and muxing locally.

This is the mechanism behind unshackle's client/server "remote download" workflow. A thin local client (RemoteService) talks to an unshackle serve instance over HTTP. The server keeps an authenticated service instance alive between requests so the client can authenticate once and then make many follow-up calls against the same remote session.

!!! note "Why you'd use this" - The server has service accounts, cookies, or a CDM you do not want to copy to every machine. - You want to do downloads on a fast/local machine but keep credentials and licensing centralised. - A service is region-locked to where the server lives, and the client is not.

---

The big picture

┌──────────────────────────┐        HTTP (X-Secret-Key)         ┌──────────────────────────┐
│  Local machine (client)  │  ───────────────────────────────▶ │   unshackle serve        │
│                          │                                    │                          │
│  unshackle dl --server   │   POST /api/session/create         │  authenticated Service   │
│                          │   GET  /api/session/{id}/titles    │  instance, kept alive in │
│  • track selection       │   POST /api/session/{id}/tracks    │  an in-memory session    │
│  • download / decrypt    │   POST /api/session/{id}/segments  │  store (TTL-based)       │
│  • mux                   │   POST /api/session/{id}/license   │                          │
│                          │   DELETE /api/session/{id}         │                          │
└──────────────────────────┘                                    └──────────────────────────┘

The client implements the same interface dl expects from a normal service, but every service-facing method proxies to the server. Everything after track selection (downloading segments, decrypting, and muxing) runs locally.

!!! note "Migration: remote_dl is gone" The RemoteService adapter lives inside the ordinary dl command and replaces the old standalone remote_dl command. If you have prior scripts or docs that invoke remote_dl, use dl with a configured remote server instead. The functionality now rides on dl through RemoteService.

For the auth-facing endpoints, header format, and error shapes referenced below, see Authentication and the endpoint reference in the REST API index.

---

Configuring a remote server (client side)

On the client, add a remote_services block to your unshackle.yaml. Each entry names a server and provides its URL and API key.

remote_services:
  my_server:
    url: "https://my-box.example:8786"
    api_key: "your-api-key"
    # Optional: let the server's CDM do the licensing instead of a local CDM
    server_cdm: false
    # Optional: per-service config overrides applied locally (title_map, cdm, etc.)
    services:
      EXAMPLE:
        title_map:
          "0ABCDEF": "The Show (Renamed Locally)"

Key	Required	Meaning
url	yes	Base URL of the unshackle serve instance (no trailing slash needed)
api_key	no	Sent as the X-Secret-Key header on every request
server_cdm	no	When true, DRM keys are resolved by the server's CDM rather than a local device (default false)
services	no	Per-service local config overrides, keyed by service tag

!!! warning "Port default" The unshackle serve default port is 8786 (not 8080). Use the port your server binds. Some older example snippets show 8080, which is not the default.

Selecting a server

If you configure exactly one server, unshackle uses it implicitly:

unshackle dl EXAMPLE 0ABCDEF

If you configure more than one server, you must pick one with --server:

unshackle dl --server my_server EXAMPLE 0ABCDEF

With no remote_services configured at all, unshackle raises a clear error telling you to add the block shown above.

---

What happens during a download

From your point of view the command looks like an ordinary download. Under the hood the client walks a remote session through its lifecycle.

=== "1. Create + authenticate"

The client calls `POST /api/session/create`, forwarding whatever it can so the
server does not have to prompt:

- Local **credentials** for the service/profile (`{username, password, extra?}`)
- Local **cookies**, compressed and base64-encoded
- A resolved **proxy**, or, if you did not set one, your detected
  **client region** so the server can auto-proxy to match it
- Track-selection hints (`range_`, `vcodec`, `quality`, `best_available`) so
  the server fetches the right manifests
- Your local per-service **cache files** (e.g. refreshed tokens)

The server responds immediately with a session ID and a status. Authentication
runs in the background on the server.

=== "2. Interactive prompts (if needed)"

Some services need a one-time code, PIN, or device confirmation. When the
server's auth flow asks for input, the remote session enters `pending_input`. The
client polls, displays the prompt to you locally, collects your answer, and
sends it back. The server's auth thread resumes with your response.

```text
Enter the 6-digit code sent to your email: 483920
```

=== "3. Titles + tracks"

Once authenticated, the client fetches the title list, then the tracks for the
chosen title. The tracks come back with playback URLs, and the server ships
DASH/ISM manifests as compressed XML so the client can re-parse them locally for
downloading. Any `session_headers` / `session_cookies` the server used are
merged into the client's local HTTP session.

The tracks response repeats the title. A service can rewrite title fields inside
`get_tracks`, so the client takes this copy in place of the one from the title
list. Each track carries the full local field set. After the manifest re-parse the
client overlays the JSON-safe part of the service-set `track.data`, so a service
value wins over the parser's. An attachment that the service wrote to a file on the
server travels as base64, and the client writes it to its own temp directory.

=== "4. Licensing"

For a DRM-protected title the client either **proxies** its CDM challenge through
the server, or, if `server_cdm: true`, asks the server to do the full CDM flow
and return the content keys directly. See
[Server-side vs. proxied CDM](#server-side-vs-proxied-cdm) below.

=== "5. Download + close"

The client downloads, decrypts, and muxes locally. On completion it deletes
the remote session. If the server has updated cache files (for example a refreshed
token), the delete returns them and the client saves them locally, so the **next**
remote session can skip interactive auth.

!!! tip "Renaming remote titles locally" You can rename titles for a remote service you do not have installed locally by adding a title_map under that service in your client remote_services.<name>.services config. The server sends raw titles. Your local map wins.

This is deliberate: the server does **no** `title_map` remapping of its own and
sends titles exactly as the service returns them. All remapping happens on the
client, applied to the titles the server sends back. It keeps the final output
name fully under the client's control and lets you rename titles even for
services you have no local install of.

---

Server-side vs. proxied CDM

There are two ways DRM keys get resolved, chosen by the client's server_cdm flag.

=== "Proxied CDM (default)"

Your **local CDM** builds the license challenge. The client sends that challenge
to `POST /api/session/{id}/license`, the server forwards it to the service, and
the raw license bytes come back for your local CDM to parse.

- Keeps your CDM local. The server only relays the license request.
- Used when `server_cdm` is `false` (the default).

=== "Server-side CDM (server_cdm: true)"

The **server's CDM** does everything. The client sends track IDs (or a PSSH),
the server checks its key vaults, loads the device configured for your API key,
runs the CDM flow, and returns `KID:KEY` pairs directly. The client needs no
CDM.

- Enable with `server_cdm: true` in the server entry.
- The server tells the client which DRM type it used
  (`widevine` or `playready`).

---

Remote session lifecycle and expiry

Remote sessions live in an in-memory store on the server and expire on a timer. You generally never touch this directly, but it explains behaviour you might observe.

Behavior	Value	Notes
Idle session TTL	300s (5 min) default	Refreshed on every request to the session
Max concurrent sessions	100 default	Oldest (least recently used) is evicted when full
Auth/input timeout	600s (10 min)	Sessions still authenticating or awaiting a prompt use this longer window instead of the TTL
Cleanup sweep	every 60s	Expired sessions are removed and their input prompts cancelled

!!! note "Auth is never rushed" A remote session that is still authenticating or waiting on pending_input is not subject to the short 300s TTL. It gets the full 600s auth window. This gives you time to enter an interactive code without the remote session vanishing mid-prompt.

The TTL and max-session limits are read from server config:

serve:
  session_ttl: 300     # seconds a session may sit idle
  max_sessions: 100    # cap on concurrent sessions

---

Security properties worth knowing

• API key required. Every remote session request carries X-Secret-Key. The server rejects requests without a valid API key (health check aside). See Authentication.
• IP binding. A remote session records the creator's IP when the server makes it. If a later request for the same remote session comes from a different IP, the server returns 403 FORBIDDEN. Remote sessions are not portable between hosts.
• Namespaced, isolated cache. Each remote session gets its own cache directory, namespaced by a hash of the API key and the remote session ID, so remote sessions cannot read each other's cached tokens. The server deletes the directory when the remote session ends.
• The server redacts secrets in logs. It redacts remote session IDs, service tags, and other user values before it writes them to the log.

---

Developer reference

!!! info "This section is for developers" The material below documents the server-side implementation and the HTTP contract. End users configuring a client can stop at the sections above.

Remote session endpoints

The server mounts all these routes, even in --remote-only mode. Paths use the session_id that create returns.

!!! note "Why --remote-only exists" --remote-only narrows the server to only the health, services, search, and remote session subset (and emits CORS headers), precisely so it is safe to sit behind Cloudflare or serve cross-origin browser clients. That trimmed surface, rather than the full --api-only mode, is what makes a CORS/Cloudflare-fronted deployment practical: reach for it when the server is public-facing or accessed from a browser origin, not when you want only the local HTTP API.

Method	Path	Purpose
POST	/api/session/create	Build + authenticate a service instance; returns a session ID immediately
GET	/api/session/{id}/titles	Fetch and cache the title list
POST	/api/session/{id}/tracks	Resolve tracks, manifests, chapters, headers/cookies for a title
POST	/api/session/{id}/segments	Resolve per-segment/track download descriptors
POST	/api/session/{id}/license	DRM licensing (proxy or server CDM)
GET	/api/session/{id}/prompt	Poll interactive auth status / pending prompt
POST	/api/session/{id}/prompt	Submit an answer to a pending prompt
GET	/api/session/{id}	Session info (validity, TTL, counts)
DELETE	/api/session/{id}	Close the remote session, return updated cache, clean up

Create: request and response

POST /api/session/create requires service and title_id. It also accepts credentials, cookies (base64 of zlib-compressed Netscape cookie file), proxy, no_proxy, profile, cache (a map of filename → base64(zlib(bytes))), client_region, cdm_type, and the track-selection hints range_, vcodec, quality, best_available, plus arbitrary service CLI options (additionalProperties: true).

The response returns before authentication finishes:

{ "session_id": "...uuid4...", "service": "EXAMPLE", "status": "authenticating" }

Authentication runs on a background thread (asyncio.to_thread(authenticate, ...)). The remote session starts in AUTHENTICATING. The client must poll the prompt endpoint until it reaches authenticated (or failed).

Interactive auth: the InputBridge

When the service calls its input function during authenticate() on the server thread, an InputBridge pauses that thread and exposes the prompt to the HTTP layer.

• AuthStatus values: authenticating, pending_input, authenticated, failed.
• InputBridge.request_input(prompt, timeout=600) blocks the sync auth thread on a threading.Event until submit_response() or cancel() fires.
• A timeout raises TimeoutError and marks the remote session FAILED.
• AUTH_INPUT_TIMEOUT = 600.0 seconds. This is also the TTL granted to AUTHENTICATING / PENDING_INPUT sessions in the store.

GET /api/session/{id}/prompt returns one of:

{ "status": "authenticated" }
{ "status": "authenticating" }
{ "status": "pending_input", "prompt": "Enter code: " }
{ "status": "failed", "error": "...message..." }

A missing remote session returns 404 SESSION_NOT_FOUND. An IP mismatch returns 403 FORBIDDEN. POST /api/session/{id}/prompt takes { "response": "..." } and returns { "status": "accepted" }. A post with no pending prompt is an INVALID_INPUT error.

SessionStore internals

Source: unshackle/core/api/session_store.py. A singleton you get from get_session_store().

• Config-driven limits. serve.session_ttl (default 300) and serve.max_sessions (default 100) are read as properties, so config changes take effect without recreating the store.
• create() evicts the least-recently-accessed remote session when at capacity, then stores a new SessionEntry. It defaults auth_status to AUTHENTICATED, and the create handler overrides it to AUTHENTICATING.
• get() refreshes last_accessed through touch(). It returns None (and deletes the entry) if an authenticated remote session has been idle longer than the TTL. Remote sessions in AUTHENTICATING / PENDING_INPUT are exempt from TTL expiry.
• cleanup_expired() runs every 60s: authenticated remote sessions expire at ttl, in-flight-auth remote sessions expire at AUTH_INPUT_TIMEOUT. The removal of a remote session cancels its InputBridge and deletes its cache directory (pruning empty parent dirs up to, but not including, the cache root).
• The server calls cancel_all_bridges() on shutdown, to unblock any waiting auth threads.

SessionEntry fields:

Field	Description
session_id	UUID4 string
service_tag	Normalized service tag
service_instance	The authenticated service object kept alive between calls
titles / title_map	Result of get_titles() and a title_id → Title map
tracks / tracks_by_title / chapters_by_title	Cached resolved tracks and chapters
creator_ip	IP recorded at create time for IP-binding checks
cache_tag	Per-session cache directory tag
input_bridge	InputBridge for interactive auth, if any
auth_status / auth_error	Current AuthStatus and last error message
created_at / last_accessed	Timestamps; last_accessed drives TTL and LRU eviction

Per-session cache namespacing

The create handler builds a Cacher namespaced as:

_sessions/<pbkdf2_hmac(sha256, X-Secret-Key, "unshackle-session-ns", 100000)[:12]>/<session_id>/<service>

The handler writes forwarded cache files into that directory before authentication. On DELETE, the handler harvests updated cache files (compressing each with zlib and base64-encoding, excluding titles_* files) and returns them under a cache field, so the client can keep refreshed tokens:

{ "status": "ok", "cache": { "tokens": "...base64(zlib(bytes))..." } }

Remote session info response

GET /api/session/{id}:

{
  "session_id": "...",
  "service": "EXAMPLE",
  "valid": true,
  "expires_in": 300,
  "track_count": 12,
  "title_count": 40
}

!!! warning "expires_in is the configured TTL, not time remaining" The expires_in value reports the store's configured session_ttl, not the seconds left before this specific remote session expires.

Reference client: RemoteService

Source: unshackle/core/remote_service.py. This is the canonical consumer of the remote session API and a good template for any client.

• RemoteClient.request sets X-Secret-Key and User-Agent: unshackle/<version>, uses a 120s timeout for POST and 30s for GET/DELETE, and treats any status_code >= 400 as fatal: it logs Server error [<error_code>]: <message> and raises SystemExit(1).
• Retries. The download-side HTTP session mounts an adapter with Retry(total=5, backoff_factor=0.2, status_forcelist=[429, 500, 502, 503, 504]).
• Flow. authenticate() → create (+ poll prompt every 2s up to a 600s deadline, answering pending_input prompts. With stdin closed the client logs an error and raises SystemExit(1) instead of posting an empty answer) → get_titles() → get_tracks() (merging returned session_headers/session_cookies, re-parsing manifests) → get the licence in proxy mode or server_cdm mode → close() (DELETE, saving any returned cache).
• Server resolution. resolve_server() reads config.remote_services.<name> into {url, api_key, services, server_cdm}, injecting the server_cdm flag into the services map as _server_cdm.

---

Troubleshooting

!!! example ""Could not connect to remote server ... Is it running?"" The client could not reach the URL. Make sure that unshackle serve operates on the server, the url/port in remote_services are correct (default port 8786), and any firewall or reverse proxy allows the connection.

!!! example "403 FORBIDDEN mid-download" The request came from a different IP than the one that made the remote session. Remote sessions are IP-bound. Do not move between networks (or NAT egress IPs) during a remote download.

!!! example "Auth times out or the prompt never resolves" Interactive auth allows up to 600s. If you miss that window, the server marks the remote session failed and cleans it up. Operate the download again. If the server never prompts you, make sure that the credentials and cookies the client forwarded are valid for the service.

!!! example ""Multiple remote services configured. Use --server ..."" You have more than one entry under remote_services. Pass --server <name> to pick one.