Headerfilter Syntax for YAML

[predic8]

Summary by CodeRabbit

• Refactor

  • Replaced legacy header-filtering with a modular header filter and interceptor offering configurable include/exclude rules and an updated configuration API.

• New Features

  • Added a tutorial demonstrating header removal using the new header-filter.

• Tests

  • Added unit tests for rule matching and filter behavior; adapted existing tests to the new API and adjusted one expected error status from 500 to 400.

• Chores

  • Added/updated Apache 2.0 license headers in multiple test files.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Replaces the legacy header-filter interceptor with a new headerfilter package: adds HeaderFilterRule, HeaderFilter, and a new HeaderFilterInterceptor; removes the old monolithic interceptor class; updates tests, imports, and adds new unit tests and a tutorial YAML.

Changes

Cohort / File(s)	Summary
Removed Legacy Interceptor core/src/main/java/com/predic8/membrane/core/interceptor/HeaderFilterInterceptor.java	Deleted old interceptor and its nested Rule/Include/Exclude types and Action enum; removed lifecycle methods.
New HeaderFilter Package - Core Classes core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterRule.java, core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilter.java, core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterInterceptor.java	Adds HeaderFilterRule (pattern + action, keep/remove factories, case-insensitive regex), HeaderFilter (applies rules over header fields and executes actions), and HeaderFilterInterceptor delegating filtering in request/response/abort hooks.
Updated Tests for New API core/src/test/java/com/predic8/membrane/core/interceptor/HeaderFilterInterceptorTest.java	Refactors tests to use headerfilter package, static keep()/remove() factories, and adjusted method signatures/usages.
New Unit Tests core/src/test/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterRuleTest.java, core/src/test/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterTest.java	Adds tests validating rule matching, case-insensitivity, repeated fields, and removal/keep semantics.
Tutorial / Examples distribution/tutorials/advanced/80-Removing-HTTP-Headers.yaml	Adds tutorial YAML demonstrating headerFilter usage and example rules.
Import / Test Hygiene & License Headers core/src/test/.../APIProxySpringConfigurationTest.java, multiple distribution/src/test/... files, annot/src/main/.../YamlParsingUtils.java	Replaces wildcard imports with targeted headerfilter imports; adds Apache-2.0 license headers in several test files; minor test expectation tweak (500→400) in one distribution test.

Sequence Diagram(s)

sequenceDiagram
  participant Client as Client
  participant HFI as HeaderFilterInterceptor
  participant HF as HeaderFilter
  participant Backend as BackendServer

  Client->>HFI: send request (Exchange/Message)
  HFI->>HF: filter request headers (apply rules)
  HF->>HF: iterate header fields, match rules, remove/keep
  HF-->>HFI: filtered headers
  HFI->>Backend: forward filtered request
  Backend-->>HFI: response
  HFI->>HF: filter response headers
  HF->>HF: iterate header fields, match rules, remove/keep
  HF-->>HFI: filtered response
  HFI-->>Client: return response

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested labels

7.x

Suggested reviewers

• rrayst
• christiangoerdes

Poem

🐰 I hopped through patterns, soft and keen,
Kept a header here, nibbled one unseen.
Regex whiskers twitching, rules in tow,
I pruned the fields and watched them go.
Tiny paws, tidy trail — off I go! 🥕

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 9.09% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Headerfilter Syntax for YAML' accurately reflects the primary changes: a comprehensive refactoring of the header filtering interceptor with new public API classes (HeaderFilter, HeaderFilterRule, HeaderFilterInterceptor) that support YAML configuration, plus a new advanced tutorial demonstrating the YAML syntax for removing HTTP headers.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

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[predic8]

XML is not working at this stage. When we agree on the change we must add the modifications for XML.

[coderabbitai]

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In
`@core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterInterceptor.java`:
- Around line 79-86: handleAbort currently calls filter(exchange.getResponse())
which will NPE if the response is missing; update handleAbort in
HeaderFilterInterceptor to guard against a null response by checking
exchange.getResponse() != null before calling filter(Message), or alternatively
make the private filter(Message msg) null-tolerant by returning early when msg
is null; reference the handleAbort method and the private filter(Message) method
(and the internal filter field used inside it) when applying the change.

In
`@core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterRule.java`:
- Around line 41-45: The XML text-content binding was lost after adding
`@MCAttribute` on setPattern causing pattern to be null and p uninitialized (NPE
in matches()); update HeaderFilterRule so setPattern(String pattern) accepts
and/or reads text-content as well as the attribute (or restore former
text-binding), and add a null/empty guard that throws an informative exception
(fail fast) if pattern is missing; ensure the compiled Pattern field p is always
initialized when pattern is set and apply the same fix to the other
pattern-compiling setter referenced in the class (the second setter that also
assigns p/matches usage).

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In
`@core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilter.java`:
- Around line 47-48: setRules currently assigns the incoming List directly which
allows a null to be stored and will cause an NPE in HeaderFilter.filter; change
HeaderFilter.setRules to guard against a null argument by replacing a null with
an empty, immutable list (e.g. Collections.emptyList()) or by validating and
throwing IllegalArgumentException, ensuring this.rules is never null when used
by HeaderFilter.filter.

♻️ Duplicate comments (1)

core/src/main/java/com/predic8/membrane/core/interceptor/headerfilter/HeaderFilterRule.java (1)

20-27: Guard against unset pattern to avoid runtime NPE.
Line 20 allows an action-only rule, but Line 52 dereferences p unconditionally. If a rule is built without setPattern, matches() will throw. Consider either enforcing a non-null pattern or using a default match-all pattern.

🛠️ Proposed fix

 `@MCTextContent`
 public void setPattern(String pattern) {
-    this.pattern = pattern;
-    p = Pattern.compile(pattern, CASE_INSENSITIVE);
+    if (pattern == null || pattern.isBlank())
+        throw new IllegalArgumentException("HeaderFilterRule pattern must be set.");
+    this.pattern = pattern;
+    p = Pattern.compile(pattern, CASE_INSENSITIVE);
 }
 
 public boolean matches(String header) {
-    return p.matcher(header).matches();
+    if (p == null)
+        throw new IllegalStateException("HeaderFilterRule pattern must be configured before use.");
+    return p.matcher(header).matches();
 }

Also applies to: 41-52