shinyhub-identity

Read the signed identity ShinyHub forwards to your app, in one call. No per-app JWT plumbing.

ShinyHub injects a short-lived, per-app HS256 JWT (X-Shinyhub-Identity-Token) into every request it proxies, and hands your app its verification key via SHINYHUB_IDENTITY_KEY and SHINYHUB_APP_SLUG. This package verifies that token and returns the identity.

pip install shinyhub-identity
# or: uv add shinyhub-identity

Use it

from shinyhub_identity.shiny import session_identity

def server(input, output, session):
    user = session_identity(session)   # None when anonymous
    if user is None:
        ...  # logged-out visitor
    elif "platform-admins" in user.groups:
        ...  # gate admin features on the VERIFIED groups

session_identity(session) verifies the session's handshake token once and returns that answer for the session's life. That is a correctness property, not a cache: ShinyHub binds identity at the WebSocket handshake, and the token it forwarded there expires five minutes later, so re-verifying those headers from a reactive starts failing part-way through a long session even though nothing about the user changed.

Outside Shiny (Streamlit, Dash, FastAPI, ...) use the framework-free primitive, which takes any header mapping - a Starlette/Flask request's headers, or a plain dict - and verifies per request:

from shinyhub_identity import current_user

user = current_user(request.headers)   # None when anonymous

Both return an Identity or None. Identity fields:

Key and slug default to the SHINYHUB_IDENTITY_KEY/SHINYHUB_APP_SLUG environment variables ShinyHub injects; pass key=/slug= explicitly for tests.

None means anonymous, and nothing else

A genuine anonymous visitor sends no token at all, so that is the only case that returns None. A token that is present but fails verification is a broken deployment - missing or wrong SHINYHUB_IDENTITY_KEY, audience or issuer mismatch, an expired token, clock skew - and raises IdentityError instead. An app that renders that as "logged out" hides the outage behind an empty dashboard, which is exactly what this contract prevents.

from shinyhub_identity import IdentityError

try:
    user = session_identity(session)
except IdentityError as e:
    log.error("identity broken: %s", e)     # e.reason, e.detail
    raise

IdentityError.reason is a stable classification (the R helper uses the same vocabulary, and a cross-language conformance test pins them together):

IdentityError.detail carries the human-readable specifics for a log line. Letting the error propagate is a reasonable default: the app is not going to render anything trustworthy anyway.

Testing your app

Because verification is strict, a signed-in code path cannot be tested with a made-up token string: it needs a genuinely valid one. shinyhub_identity.testing mints those.

from shinyhub_identity.shiny import session_identity
from shinyhub_identity.testing import fake_session, identity_env

def test_admins_see_the_panel():
    with identity_env():
        session = fake_session(username="alice", groups=["platform-admins"])
        assert session_identity(session).username == "alice"

identity_env() sets the two environment variables ShinyHub injects (and restores them afterwards), so the app calls session_identity(session) exactly as it does in production. fake_headers(...) is the equivalent for current_user(headers), and an anonymous request is just {}.

Every rejection path is one argument, so a test names the thing that is wrong:

mint_token(expires_in=-60)          # -> expired
mint_token(key=b"\xff" * 32)        # -> bad_signature
mint_token(slug="other-app")        # -> wrong_audience
mint_token(issuer="evil")           # -> wrong_issuer
fake_headers(token="not-a-jwt")     # -> malformed

The tokens are real, not stubs. They carry the same claim set the proxy mints, including which claims are omitted when empty, so an app that reads user.claims["email"] fails in a test exactly where it would fail in production. ShinyHub's conformance suite checks this field by field against the production minter and fails if either side drifts.

This module is for tests only. The default key is a fixed, published constant, so tokens minted with it are forgeable by anyone.

Local development

With no ShinyHub proxy in front there is no token, so the identity is always None. Instead of writing a per-app mock, set:

export SHINYHUB_IDENTITY_DEV_USER=devlin
export SHINYHUB_IDENTITY_DEV_GROUPS="team-a, team-b"   # optional
export SHINYHUB_IDENTITY_DEV_EMAIL=devlin@example.com  # optional
export SHINYHUB_IDENTITY_DEV_NAME="Devlin Example"     # optional
export SHINYHUB_IDENTITY_DEV_ROLE=admin                # optional, default viewer

Both helpers then return a synthetic Identity marked with claims == {"dev": True, ...}. This can never activate under a real deployment: it only applies when no token arrived and SHINYHUB_IDENTITY_KEY is absent, and ShinyHub always injects that key into app processes.

Compatibility

Requires Python 3.10+.

This helper is versioned independently of the ShinyHub server: its version tracks changes to this package's API, not the server's release train. Any release verifies tokens from any ShinyHub v0.8.6 or later (the release that introduced identity forwarding); the token contract is stable across server releases. Claims a later server added (email, name) are simply "" when an older server minted the token.

Upgrading from 0.3: additive only. shinyhub_identity.testing is new; nothing else changed.

Upgrading from 0.2: a rejected token now raises IdentityError instead of returning None with a warning, so code that treated None as "not logged in" should either let the error propagate or catch it explicitly. Identity is keyword-only now, and Shiny apps should call session_identity(session) rather than current_user(session.http_conn.headers).

Why verify, not just read the plain headers?

ShinyHub also forwards convenience plain headers (X-Shinyhub-User, -Role, -Groups, ...) and strips any client-supplied ones. But app processes listen on host-local ports, so a co-located process can bypass the proxy and forge plain headers. Anything that gates access must verify the token - which is exactly what this package does. See ShinyHub's docs/identity.md for the full trust model.