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Add OAuth2 resource server project: JWT validation, JWKS and key rotation

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
This commit is contained in:
2026-08-23 11:00:56 +00:00
parent 4a8dab6739
commit 4dc45d5e00
101 changed files with 4087 additions and 64 deletions

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@@ -91,7 +91,7 @@ this.mvc.perform(post("/api/auth/login").with(csrf()) ... )
```
Convenient, and it will make a test pass against a configuration that 403s in production.
[`CsrfBreaksPermitAllTests`](../src/test/java/com/ankurm/jwtauth/CsrfBreaksPermitAllTests.java)
[`CsrfBreaksPermitAllTests`](../jwt-authentication/src/test/java/com/ankurm/jwtauth/CsrfBreaksPermitAllTests.java)
deliberately has both tests: one asserting the 403 **without** `csrf()`, one asserting the
200 with it. If you only ever write the second, you have tested your test.
@@ -125,7 +125,7 @@ already in the past.
## Integration testing against the real server
`scripts/curl-transcript.sh` is the integration test that MockMvc cannot be — it exercises
`jwt-authentication/scripts/curl-transcript.sh` is the integration test that MockMvc cannot be — it exercises
a real Tomcat, a real HTTP client, real header parsing, and real base64url. Several
findings in these docs (the `resource_metadata` parameter, the `FACTOR_BEARER` authority,
the bare `WWW-Authenticate` on a wrapped `JwtException`) came from that script, not from