Ankur Mhatre
4dc45d5e00
Companion code for the follow-up article. The repository now holds two Maven
projects sharing one docs/ tree:
jwt-authentication/ the hand-written filter application (unchanged, moved)
oauth2-resource-server/ a resource server, a Keycloak compose, and a stub
issuer whose JWK Set can be mutated on command
The stub exists because Keycloak will not rotate a signing key at a chosen
second, report how many times its JWKS endpoint was fetched, or drop a key from
the published set on request - and the caching and rotation measurements need
all three. The Keycloak run confirms the same code path against a real issuer.
Findings captured under docs/output/, all from real runs:
* The default validator stack does not check aud. A token minted for another
service in the same realm is accepted.
* Spring Security builds its JWKSource with refreshAheadCache(false) and
rateLimited(false), overriding two of Nimbus's protective defaults, and
enables Nimbus caching only when NO Spring cache was supplied - so
supplying one removes the five-minute expiry.
* A key retired from the JWK Set stops being accepted at t+300s with the
default cache, and never with a Spring cache that has no TTL.
* 25 tokens carrying an unknown kid produce 25 JWKS fetches at the issuer,
through permitAll() endpoints included.
* A hyphenated client id in an authorities-claim-expression parses as
subtraction; the SpelEvaluationException is swallowed and logged at TRACE.
* A clientScopes key in a Keycloak realm import replaces the built-in scopes
rather than adding to them.
New docs chapters 12-18. README covers both projects. Existing docs and scripts
updated for the new paths; no docs/output/ file from the first article moved, so
links in the published article still resolve.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013f7f2XZXrQ6gW3RtZE187t
80 lines
3.0 KiB
Plaintext
80 lines
3.0 KiB
Plaintext
--------------------------------------------------------------------------
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Keycloak discovery document
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--------------------------------------------------------------------------
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issuer http://localhost:8080/realms/demo
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jwks_uri http://localhost:8080/realms/demo/protocol/openid-connect/certs
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token_endpoint http://localhost:8080/realms/demo/protocol/openid-connect/token
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--------------------------------------------------------------------------
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Keycloak JWK Set
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--------------------------------------------------------------------------
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keys published: 2
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kid=drdWA3YaK3PfH8uKORPsqYsf30mlkxtLKJdvYFzWqO4 alg=RSA-OAEP use=enc kty=RSA
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kid=B8LKu8nKy9b_CCTMqaZBdRH7dH1ASVjg5Do5hElKpQE alg=RS256 use=sig kty=RSA
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--------------------------------------------------------------------------
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1. alice, password grant
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--------------------------------------------------------------------------
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header: {"alg": "RS256", "typ": "JWT", "kid": "B8LKu8nKy9b_CCTMqaZBdRH7dH1ASVjg5Do5hElKpQE"}
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iss "http://localhost:8080/realms/demo"
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aud "reports-api"
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typ "Bearer"
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scope "email profile"
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preferred_username "alice"
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realm_access {"roles": ["USER"]}
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resource_access {"reports-api": {"roles": ["reports-reader"]}}
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$ GET /api/me
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HTTP 200
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{
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"name": "alice",
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"authorities": [
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"FACTOR_BEARER",
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"ROLE_USER",
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"ROLE_reports-reader",
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"SCOPE_email",
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"SCOPE_profile"
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],
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"iss": "http://localhost:8080/realms/demo",
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"aud": [
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"reports-api"
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],
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"typ": "JWT",
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"kid": "B8LKu8nKy9b_CCTMqaZBdRH7dH1ASVjg5Do5hElKpQE",
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"exp": "2026-08-23T10:38:53Z"
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}
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$ GET /api/reports (client role, from resource_access.reports-api.roles)
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HTTP 200
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{
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"reports": 3
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}
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$ GET /api/admin/stats (realm role ADMIN, which alice does not have)
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HTTP 403
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WWW-Authenticate: Bearer error="insufficient_scope", error_description="The request requires higher privileges than provided by the access token.", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1"
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--------------------------------------------------------------------------
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2. root
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--------------------------------------------------------------------------
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$ GET /api/admin/stats
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HTTP 200
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{
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"secret": "only ROLE_ADMIN sees this"
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}
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--------------------------------------------------------------------------
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3. nobody - a user with no client role
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--------------------------------------------------------------------------
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header: {"alg": "RS256", "typ": "JWT", "kid": "B8LKu8nKy9b_CCTMqaZBdRH7dH1ASVjg5Do5hElKpQE"}
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iss "http://localhost:8080/realms/demo"
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aud "reports-api"
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typ "Bearer"
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scope "email profile"
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preferred_username "nobody"
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realm_access {"roles": ["USER"]}
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$ GET /api/reports
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HTTP 403
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WWW-Authenticate: Bearer error="insufficient_scope", error_description="The request requires higher privileges than provided by the access token.", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1"
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