REST API Authentication¶

The unshackle REST API protects every endpoint (with one exception) behind a single API key. Clients present that key in a request header, and the server checks it against the keys defined in your configuration. This page explains how that check works, how to configure keys, how clients send them, and the extra controls that build on top of the key: per-key service allowlists, per-key CDM device access, and session IP binding.

The API is started with the unshackle serve command. Authentication is on by default: if you start the server without an API key configured, it refuses to launch.

Which server am I running?

unshackle serve can run in two shapes, and each uses a slightly different piece of code to check your key:

The integrated server (the default) exposes the REST API and the pywidevine / pyplayready CDM HTTP endpoints.
The API-only server (--api-only, also implied by --remote-only) exposes only the REST API.

The header, the config, and the behaviour you see as a client are the same in both. The differences are internal and are called out in the developer notes below.

The short version¶

Add an api_secret to the serve section of your unshackle.yaml.
Start the server with unshackle serve.
Send that secret in the X-Secret-Key header on every request except GET /api/health.

A minimal authenticated request

curl -H "X-Secret-Key: your-secret-key-here" \
     http://127.0.0.1:8786/api/services

Configuring authentication¶

All authentication settings live under the serve section of your unshackle config file (unshackle.yaml).

A single API key¶

The simplest setup defines one shared secret with api_secret:

unshackle.yaml

serve:
  api_secret: "a-long-random-secret-string"

This value becomes the one and only key that the server accepts. Requests that present it in the X-Secret-Key header are allowed; everything else is rejected.

The server will not start without a key

If you start unshackle serve with no api_secret configured, and you have not passed --no-key, the command fails immediately with:

API secret key is not configured. Please add 'api_secret' to the 'serve' section in your config.

Choose a long, unpredictable value. The key is the only thing standing between the internet and your CDM and download endpoints.

Multiple keys with `users`¶

For finer control you can define named users, each with their own key. A user entry can also grant CDM device access and restrict which services that key may touch:

unshackle.yaml

serve:
  api_secret: "the-primary-admin-key"
  users:
    a-secret-key-for-alice:
      username: alice
      devices: ["my_widevine_device"]         # Widevine (.wvd) devices this key may use
      playready_devices: ["my_playready_prd"]  # PlayReady (.prd) devices this key may use
      services: ["EXAMPLE1", "EXAMPLE2"]       # optional per-key service allowlist
    a-secret-key-for-bob:
      username: bob
      devices: ["my_widevine_device"]

The key of each entry under users (for example a-secret-key-for-alice) is the secret that client sends in X-Secret-Key. The username is a human-readable label used in logs and in job/history metadata.

How api_secret and users combine (integrated server)

On the integrated server, the configured api_secret is automatically added as an extra accepted key alongside everyone in users. It is granted access to all loaded Widevine and PlayReady devices and is labelled api_user. So api_secret behaves as an admin-level key in addition to any named users you define.

On the API-only server, only api_secret is accepted: the single-key model. (See the developer notes for the exact difference.)

CDM device access per key¶

Under the integrated server, a key can only run DRM licensing through a CDM device that its user entry lists:

Config key	Grants access to
`devices`	Widevine `.wvd` devices, by name
`playready_devices`	PlayReady `.prd` devices, by name

PlayReady access is opt-in per user

If a user entry omits playready_devices, that key is given no PlayReady access, and the server logs a warning at startup. You must list PlayReady devices explicitly for any key that needs them. Widevine and PlayReady device files themselves are auto-loaded from your WVDs and PRDs directories.

Device lists are the server-side-decryption switch

There is no separate tier, capability flag, or permission toggle for whether the server will hand back keys (KID:KEY) for a session download. The presence of devices on the calling key decides it. With empty devices and playready_devices, the server can only proxy CDM challenges, so the client must run its own CDM. Once those lists are populated, the client may request mode:server_cdm and receive keys back. Don't go looking for a tier setting; configuring devices is what enables server-side decryption.

Disabling authentication¶

The --no-key flag turns authentication off entirely. Every request is allowed, X-Secret-Key is ignored, and no key needs to be configured.

unshackle serve --no-key

Only use --no-key on a trusted, isolated network

With --no-key there is nothing stopping any client that can reach the port from listing your services, starting downloads, or using your CDM devices. Never expose a --no-key server to an untrusted network.

How clients present credentials¶

Clients authenticate by sending the secret in a single HTTP request header on every call:

X-Secret-Key: <your-secret>

The value must exactly match one of the configured keys (api_secret, or one of the keys under users). There is no login step, no session cookie, and no token exchange for API access. The same static key is sent on each request.

curlPython (requests)JavaScript (fetch)

curl -H "X-Secret-Key: your-secret-key-here" \
     http://127.0.0.1:8786/api/services

import requests

BASE = "http://127.0.0.1:8786"
HEADERS = {"X-Secret-Key": "your-secret-key-here"}

resp = requests.get(f"{BASE}/api/services", headers=HEADERS, timeout=30)
resp.raise_for_status()
print(resp.json())

const resp = await fetch("http://127.0.0.1:8786/api/services", {
  headers: { "X-Secret-Key": "your-secret-key-here" },
});
if (!resp.ok) throw new Error(`Server returned ${resp.status}`);
console.log(await resp.json());

The reference client sets it for you

unshackle's own remote download client (RemoteService) sends X-Secret-Key automatically, reading the key from your remote_services config. It also sends a User-Agent of unshackle/<version>. You only deal with the header directly when writing your own client.

The health check is always open¶

One endpoint is exempt from authentication: GET /api/health. It never requires a key, so you can use it for liveness and version probes without embedding a secret in your monitoring:

No key needed

curl http://127.0.0.1:8786/api/health

Response

{
  "status": "ok",
  "version": "5.3.0",
  "update_check": {
    "update_available": null,
    "current_version": "5.3.0",
    "latest_version": null
  }
}

Every other endpoint (including the Swagger UI at /api/docs/ on the API-only server) requires a valid key.

Authentication failures¶

When a request is rejected for authentication reasons, the response has an HTTP 401 Unauthorized status and a small JSON body.

Missing headerWrong key

Sending a request with no X-Secret-Key header:

{
  "status": 401,
  "message": "Secret Key is Empty."
}

Sending a key that is not in your config:

{
  "status": 401,
  "message": "Secret Key is Invalid."
}

Auth errors use a different JSON shape than other errors (developer note)

The rest of the API reports errors with a structured body containing error_code, message, timestamp, and other fields (see Errors). The authentication middleware is different: it returns {"status": 401, "message": "..."}, where status is an integer, and there is no error_code or timestamp.

A robust client should treat any 401 as an authentication problem and be prepared to parse both shapes rather than assuming the standard error body is always present.

Building on the key: access controls¶

Once a request is authenticated, several additional controls decide what that specific key is allowed to do.

Per-key service allowlists¶

You can restrict which services a key may use. Two layers combine:

Global allowlist: serve.services, applied to every key.
Per-key allowlist: services inside that key's users entry.

The effective allowlist for a request is:

Global set?	Per-key set?	Result
Yes	Yes	The intersection of the two
Yes	No	The global list
No	Yes	The per-key list
No	No	No restriction, all services allowed

Restricting services

serve:
  api_secret: "admin-key"
  services: ["EXAMPLE1", "EXAMPLE2", "EXAMPLE3"]   # global ceiling for all keys
  users:
    limited-key:
      username: limited
      services: ["EXAMPLE1"]          # this key ends up allowed only EXAMPLE1

Endpoints that name a service (listing services, searching, listing titles/tracks, downloading, profiles, history, and remote sessions) all filter against this allowlist. A request for a service outside the key's allowlist is rejected as an invalid service. Service tags are matched after normalization, so casing and aliases resolve consistently.

CDM overrides and per-job credentials¶

Two download-time capabilities are gated behind server config and, unless enabled, are refused with 403 Forbidden even for an authenticated key:

Config key	Default	Controls
`serve.cdm_overrides`	off	Whether a request may pick a specific CDM device via the `cdm` field. Set to `true` to allow any, or to a list/set of device names to allow only those.
`serve.allow_job_credentials`	off	Whether a request may pass its own `credential` / `credentials` login details for a download job.

Opting in to per-request CDM and credentials

serve:
  api_secret: "admin-key"
  cdm_overrides: ["my_widevine_device"]  # or true to allow any configured device
  allow_job_credentials: true

When to enable these gates

The two gates are fully independent and can be combined. The intended posture is that a locked-down or public-facing deployment leaves both unset (they default off and reject with 403) so client requests can never steer the server's CDM or feed it their own logins. Enabling them only makes sense for a trusted single-client deployment, where the caller and the operator are effectively the same party.

Client-supplied credentials get isolated token caches

When allow_job_credentials is enabled and a download job supplies its own credential / credentials, each distinct credential is given its own isolated token cache on the server. Client-supplied logins are never shared or merged with the server's configured-credential caches, so they cannot cross-contaminate or read the server's own token state, and they don't clobber each other.

See Downloads for how these fields are used on the download endpoint.

Session IP binding (remote sessions)¶

The remote-download session endpoints (/api/session/*) add an extra check on top of the key. When a session is created, the server records the client's IP address. Any later request for that session must come from the same IP, or it is rejected with 403 Forbidden. This means a session is bound both to the key that created it and to the address it was created from.

Transport security (HTTPS)¶

The API server speaks plain HTTP. Because your key is sent on every request, you should not expose it over an unencrypted connection on an untrusted network. To serve over HTTPS, run a reverse proxy in front of unshackle. The serve command can launch Caddy for you:

unshackle serve --caddy

With --caddy, unshackle also starts caddy run using the Caddyfile located next to your unshackle config, letting you terminate TLS and reverse-proxy to the API. Configuring Caddy itself (certificates, domains, upstream) is done in that Caddyfile.

Quick reference¶

Item	Value
Auth header	`X-Secret-Key`
Default bind address	`127.0.0.1:8786`
Exempt endpoint	`GET /api/health`
Failure status	`401 Unauthorized`
Missing-header body	`{"status": 401, "message": "Secret Key is Empty."}`
Invalid-key body	`{"status": 401, "message": "Secret Key is Invalid."}`
Disable auth	`--no-key` (all requests allowed)
Config location	`serve.api_secret` and `serve.users` in `unshackle.yaml`

Developer notes: how the check is implemented¶

This section is for people writing or debugging the server, not for API consumers.

Two middlewares, one header¶

The header and config are identical between modes, but the code that enforces them differs:

API-only server (--api-only, or --remote-only which forces API-only). An api_key_authentication middleware runs on every request. It lets GET /api/health through unconditionally, then reads X-Secret-Key. An empty header returns the "Secret Key is Empty." body; a header that is not a configured user returns "Secret Key is Invalid.". In this mode the accepted-keys map contains exactly one entry: your api_secret (labelled api_user, with no devices). With --no-key, this middleware is simply not installed and the users map is empty.
Integrated server (default). A serve_authentication middleware wraps pywidevine's authentication (and pyplayready's for /playready* paths), and the REST routes live in the same application, guarded by the same check. Here the accepted-keys map is your full serve config: api_secret (auto-added with access to all loaded devices) plus every entry under users, each with its declared devices / playready_devices.

Because the API-only middleware guards all non-health paths, the Swagger UI at /api/docs/ is also behind X-Secret-Key there. In --remote-only mode the Swagger UI is not mounted at all.

CORS and the `Authorization` header¶

A cors_middleware runs on every response in both modes (and answers OPTIONS preflight requests with an empty response). It emits:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Headers: Content-Type, X-Secret-Key, Authorization
Access-Control-Max-Age: 3600

The REST API authenticates with X-Secret-Key; Authorization is advertised because the co-hosted pywidevine / pyplayready CDM endpoints use it. PUT appears in the allowed methods list but no REST route uses it; only GET, POST, and DELETE are wired up.

Where device access is read¶

The map of accepted keys lives at request.app["config"]["users"]. For DRM operations, a key's permitted Widevine devices come from its devices list and PlayReady devices from playready_devices; the first configured device is used when a request does not (or may not) override it. A server-wide config.cdm[<service>] mapping, if present, takes precedence over the key's device list when resolving which device to use.