Implement basic route matching for xDS clients

[jrhee17]

Motivation:

Following #6322, this changeset attempts to implement route matching (Route#match).
ref: https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto#envoy-v3-api-msg-config-route-v3-route

Implementation is focused on following upstream behavior as closely as possible.
The corresponding implementation can be found here: https://github.com/envoyproxy/envoy/blob/4bb05db55ecd583b6f451d81445d94210445176f/source/common/router/config_impl.cc#L831-L881

Matching rules that aren't implemented are:

• tls_context: Since the client doesn't act as a proxy yet, there are no downstream tls contexts.
• dynamic_metadata: While this may be useful, users don't have a way to supply a metadata directly for a request yet.
• runtime_fraction: This will be implemented when rtds is implemented.
• filter_state: may consider this when the set_filter_state filter is introduced.
  Overall, the above rules have been verified to not being used in basic istio cases.

Modifications:

• Implemented RouteEntryMatcher which matches a route based on the path, headers and query parameters.
• Added a dependency to re2j, which provides linear time regex matching.
  • ref: https://www.envoyproxy.io/docs/envoy/latest/api-v3/type/matcher/v3/regex.proto#envoy-v3-api-msg-type-matcher-v3-regexmatcher
  • Note that the default regex engine is re2j in bootstrap#default_regex_engine
    • https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/bootstrap/v3/bootstrap.proto
• Misc) Added CLAUDE.md to .gitignore since it seems like other major repositories aren't checking in this file either.

Result:

• The xDS integration can now route requests based on the path, headers, and query parameters.

[codecov]

Codecov Report

❌ Patch coverage is 20.83333% with 152 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.46%. Comparing base (8150425) to head (13fa4fe).
⚠️ Report is 131 commits behind head on main.

Files with missing lines	Patch %	Lines
...armeria/xds/client/endpoint/RouteEntryMatcher.java	18.13%	136 Missing and 13 partials ⚠️
...ecorp/armeria/xds/client/endpoint/RouteConfig.java	57.14%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##               main    #6333     +/-   ##
===========================================
  Coverage     74.46%   74.46%             
- Complexity    22234    22694    +460     
===========================================
  Files          1963     2031     +68     
  Lines         82437    84336   +1899     
  Branches      10764    11000    +236     
===========================================
+ Hits          61385    62803   +1418     
- Misses        15918    16279    +361     
- Partials       5134     5254    +120     

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[github-actions]

🔍 Build Scan® (commit: dc827dc)

Job name	Status	Build Scan®
build-ubicloud-standard-16-jdk-8	❌ (failure)	https://ge.armeria.dev/s/sl463iqh3s7ai
build-ubicloud-standard-16-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/hoxc3csayj7v2
build-ubicloud-standard-16-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/idxedirqdahl6
build-ubicloud-standard-16-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/syhtroxmqjkbc
build-ubicloud-standard-16-jdk-17-leak	✅	https://ge.armeria.dev/s/psvvcqqs6gyz6
build-ubicloud-standard-16-jdk-11	✅	https://ge.armeria.dev/s/cvrhnkal5lufm
build-macos-latest-jdk-21	✅	https://ge.armeria.dev/s/jnxpslbxxhp3u

[ikhoon]

Nice work! 👍 👍

[ikhoon]

Noted, the order of header values is crucial to match multiple headers.

[ikhoon]

Note that this will not match other Extended CONNECT requests (WebSocket and the like) as they are normalized in Envoy as HTTP/1.1 style upgrades.

I understand that the CONNECT_MATCHER implementation does not follow the Envoy's specification, as CONNECT is used for WebSocket in Armeria.

[jrhee17]

CONNECT is used for WebSocket in Armeria.

I don't really see a difference since for HTTP1 CONNECT isn't used either (and http2 websockets aren't supported in envoy).

armeria/core/src/main/java/com/linecorp/armeria/client/websocket/DefaultWebSocketClient.java

Line 146 in 6e479a3

builder.method(HttpMethod.GET)

Nuances on the request state may differ, but the condition is more or less the same.

• https://github.com/envoyproxy/envoy/blob/f5bc3c5fd2594e30f912ce2b3e85b297d7412b75/source/common/router/config_impl.cc#L1500
• https://github.com/envoyproxy/envoy/blob/f5bc3c5fd2594e30f912ce2b3e85b297d7412b75/source/common/http/header_utility.cc#L247

[minwoox]

👍 👍 👍