Triple Rest Openapi Support

[oxsean]

What is the purpose of the change?

Add OpenAPI support for Triple REST protocol, enabling automatic OpenAPI documentation generation
for dubbo services. The implementation includes:

• Dynamic OpenAPI spec generation from service metadata
• Support for JSON/YAML formats
• Configurable schema naming strategy
• Document caching and merging
• Group/Version/Tag filtering
• Customizable documentation through annotations

How to testing

Automatically generates OpenAPI documentation for all Dubbo services with zero configuration:

1. Access Swagger UI:

   http://host:port/dubbo/openapi
   

2. Access OpenAPI Spec:

   http://host:port/dubbo/openapi/api-docs
   

3. Supported formats:

   • JSON (default): /dubbo/openapi/api-docs
   • YAML: /dubbo/openapi/api-docs.yaml

4. Optional filters:

   • Group: /dubbo/openapi/api-docs/{group}
   • Version: /dubbo/openapi/api-docs?version=1.0.0
   • Tags: /dubbo/openapi/api-docs?tag=user,order

Example

Start dubbo-demo/dubbo-demo-spring-boot/dubbo-demo-spring-boot-servlet
then access:

http://localhost:8082/dubbo/openapi

Show case

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 6.66538% with 4831 lines in your changes missing coverage. Please review.

Project coverage is 60.75%. Comparing base (3c43c82) to head (7a9f62c).

Files with missing lines	Patch %	Lines
...java/org/apache/dubbo/metadata/OpenAPIRequest.java	0.00%	555 Missing ⚠️
...pc/protocol/tri/rest/openapi/DefinitionMerger.java	0.00%	377 Missing ⚠️
.../protocol/tri/rest/openapi/DefinitionResolver.java	0.00%	240 Missing ⚠️
...bo/rpc/protocol/tri/rest/openapi/model/Schema.java	0.00%	240 Missing ⚠️
...pc/protocol/tri/rest/openapi/DefinitionFilter.java	0.00%	231 Missing ⚠️
...in/java/org/apache/dubbo/metadata/OpenAPIInfo.java	0.00%	195 Missing ⚠️
...port/swagger/JavadocOpenAPIDefinitionResolver.java	0.00%	167 Missing ⚠️
...he/dubbo/rpc/protocol/tri/rest/openapi/Helper.java	0.00%	165 Missing ⚠️
.../rpc/protocol/tri/rest/openapi/SchemaResolver.java	0.00%	154 Missing ⚠️
...otocol/tri/rest/openapi/DefaultOpenAPIService.java	0.00%	143 Missing ⚠️
... and 109 more

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #14924      +/-   ##
============================================
- Coverage     64.34%   60.75%   -3.60%     
- Complexity    10782    10864      +82     
============================================
  Files          1819     1882      +63     
  Lines         80959    85983    +5024     
  Branches      12039    12876     +837     
============================================
+ Hits          52094    52238     +144     
- Misses        23477    28296    +4819     
- Partials       5388     5449      +61     

Flag	Coverage Δ
integration-tests	33.06% <2.74%> (-1.67%)	⬇️
samples-tests	29.22% <1.42%> (-1.81%)	⬇️
unit-tests	58.91% <6.62%> (-3.47%)	⬇️

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[zrlw]

NPE will be thrown at org.apache.dubbo.rpc.protocol.tri.servlet.HttpMetadataAdapter because request.getHeader(HttpHeaderNames.HOST.getName()) will return null if using http2.

@Override
    public HttpHeaders headers() {
            headers.add(PseudoHeaderName.METHOD.value(), method());
            headers.add(PseudoHeaderName.SCHEME.value(), request.getScheme());
            headers.add(PseudoHeaderName.AUTHORITY.value(), request.getHeader(HttpHeaderNames.HOST.getName()));
            headers.add(PseudoHeaderName.PROTOCOL.value(), request.getProtocol());
            this.headers = headers;

https://github.com/apache/dubbo-samples/tree/master/2-advanced/dubbo-samples-triple-servlet NPE:

[DUBBO] Initialize executor failed., dubbo version: 3.3.4-SNAPSHOT, current host: 172.27.0.3, error code: 0-18. This may be caused by , go to https://dubbo.apache.org/faq/0/18 to find instructions. 
2025-02-16T08:06:02.1996318Z java.lang.NullPointerException: value
2025-02-16T08:06:02.1997279Z 	at io.netty.util.internal.ObjectUtil.checkNotNull(ObjectUtil.java:39) ~[netty-common-4.1.107.Final.jar:4.1.107.Final]
2025-02-16T08:06:02.1998664Z 	at io.netty.handler.codec.DefaultHeaders.add(DefaultHeaders.java:331) ~[netty-codec-4.1.107.Final.jar:4.1.107.Final]
2025-02-16T08:06:02.2000554Z 	at org.apache.dubbo.remoting.http12.netty4.NettyHttpHeaders.add(NettyHttpHeaders.java:82) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2002451Z 	at org.apache.dubbo.rpc.protocol.tri.servlet.jakarta.HttpMetadataAdapter.headers(HttpMetadataAdapter.java:58) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2004703Z 	at org.apache.dubbo.rpc.protocol.tri.transport.TripleIsolationExecutorSupport.getServiceKey(TripleIsolationExecutorSupport.java:46) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2007068Z 	at org.apache.dubbo.rpc.executor.AbstractIsolationExecutorSupport.getProviderModel(AbstractIsolationExecutorSupport.java:64) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2009377Z 	at org.apache.dubbo.rpc.executor.AbstractIsolationExecutorSupport.getExecutor(AbstractIsolationExecutorSupport.java:41) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2011790Z 	at org.apache.dubbo.rpc.protocol.tri.h12.AbstractServerTransportListener.getExecutor(AbstractServerTransportListener.java:137) ~[dubbo-3.3.4-SNAPSHOT.jar:3.3.4-SNAPSHOT]
2025-02-16T08:06:02.2014200Z 	at org.apache.dubbo.rpc.protocol.tri.h12.grpc.GrpcHttp2ServerTransportListener.initializeExecutor(GrpcHttp2ServerTransportListener.java:64) 

it might be fixed by #15141