Spring Cloud Gateway 接口文档聚合实现

在微服务架构下，通常每个微服务都会使用Swagger来管理我们的接口文档，当微服务越来越多，接口查找管理无形中要浪费我们不少时间，毕竟懒是程序员的美德。

由于swagger2暂时不支持webflux 走了很多坑，完成这个效果感谢 @dreamlu @世言。

文档聚合效果

通过访问网关的 host:port/swagger-ui.html，即可实现: pig聚合文档效果预览传送门

通过右上角的Select a spec 选择服务模块来查看swagger文档

Spring Cloud Gateway 接口文档聚合实现

Pig的Zuul 核心实现

获取到zuul配置的路由信息，主要到SwaggerResource

/**
* 参考jhipster
* GatewaySwaggerResourcesProvider
*/
@Component
@Primary
public class RegistrySwaggerResourcesProvider implements SwaggerResourcesProvider {
    private final RouteLocator routeLocator;
    public RegistrySwaggerResourcesProvider(RouteLocator routeLocator) {
        this.routeLocator = routeLocator;
    }
    
    @Override
    public List<SwaggerResource> get() {
        List<SwaggerResource> resources = new ArrayList<>();
        List<Route> routes = routeLocator.getRoutes();
        routes.forEach(route -> {
            //授权不维护到swagger
            if (!StringUtils.contains(route.getId(), ServiceNameConstant.AUTH_SERVICE)){
                resources.add(swaggerResource(route.getId(), route.getFullPath().replace("**", "v2/api-docs")));
            }
        });
        return resources;
    }

    private SwaggerResource swaggerResource(String name, String location) {
        SwaggerResource swaggerResource = new SwaggerResource();
        swaggerResource.setName(name);
        swaggerResource.setLocation(location);
        swaggerResource.setSwaggerVersion("2.0");
        return swaggerResource;
    }
}

PigX的Spring Cloud Gateway 实现

注入路由到SwaggerResource

@Component
@Primary
@AllArgsConstructor
public class SwaggerProvider implements SwaggerResourcesProvider {
    public static final String API_URI = "/v2/api-docs";
    private final RouteLocator routeLocator;
    private final GatewayProperties gatewayProperties;


    @Override
    public List<SwaggerResource> get() {
        List<SwaggerResource> resources = new ArrayList<>();
        List<String> routes = new ArrayList<>();
        routeLocator.getRoutes().subscribe(route -> routes.add(route.getId()));
        gatewayProperties.getRoutes().stream().filter(routeDefinition ->     routes.contains(routeDefinition.getId()))
            .forEach(routeDefinition -> routeDefinition.getPredicates().stream()
                .filter(predicateDefinition -> "Path".equalsIgnoreCase(predicateDefinition.getName()))
                .filter(predicateDefinition -> !"pigx-auth".equalsIgnoreCase(routeDefinition.getId()))
                .forEach(predicateDefinition -> resources.add(swaggerResource(routeDefinition.getId(),
                    predicateDefinition.getArgs().get(NameUtils.GENERATED_NAME_PREFIX + "0")
                        .replace("/**", API_URI)))));
        return resources;
    }

    private SwaggerResource swaggerResource(String name, String location) {
        SwaggerResource swaggerResource = new SwaggerResource();
        swaggerResource.setName(name);
        swaggerResource.setLocation(location);
        swaggerResource.setSwaggerVersion("2.0");
        return swaggerResource;
    }
}

提供swagger 对外接口配置

@Slf4j
@Configuration
@AllArgsConstructor
public class RouterFunctionConfiguration {
    private final SwaggerResourceHandler swaggerResourceHandler;
    private final SwaggerSecurityHandler swaggerSecurityHandler;
    private final SwaggerUiHandler swaggerUiHandler;

    @Bean
    public RouterFunction routerFunction() {
        return RouterFunctions.route(
            .andRoute(RequestPredicates.GET("/swagger-resources")
                .and(RequestPredicates.accept(MediaType.ALL)), swaggerResourceHandler)
            .andRoute(RequestPredicates.GET("/swagger-resources/configuration/ui")
                .and(RequestPredicates.accept(MediaType.ALL)), swaggerUiHandler)
            .andRoute(RequestPredicates.GET("/swagger-resources/configuration/security")
                .and(RequestPredicates.accept(MediaType.ALL)), swaggerSecurityHandler);

    }
}

业务handler 的实现

    @Override
    public Mono<ServerResponse> handle(ServerRequest request) {
        return ServerResponse.status(HttpStatus.OK)
            .contentType(MediaType.APPLICATION_JSON_UTF8)
            .body(BodyInserters.fromObject(swaggerResources.get()));
    }
    
    @Override
    public Mono<ServerResponse> handle(ServerRequest request) {
        return ServerResponse.status(HttpStatus.OK)
            .contentType(MediaType.APPLICATION_JSON_UTF8)
            .body(BodyInserters.fromObject(
                Optional.ofNullable(securityConfiguration)
                    .orElse(SecurityConfigurationBuilder.builder().build())));
    }
    
    @Override
    public Mono<ServerResponse> handle(ServerRequest request) {
        return ServerResponse.status(HttpStatus.OK)
            .contentType(MediaType.APPLICATION_JSON_UTF8)
            .body(BodyInserters.fromObject(
                Optional.ofNullable(uiConfiguration)
                    .orElse(UiConfigurationBuilder.builder().build())));
    }

swagger路径转换

通过以上配置，可以实现文档的参考和展示了，但是使用swagger 的 try it out 功能发现路径是路由切割后的路径比如：

swagger 文档中的路径为：主机名：端口：映射路径少了一个 服务路由前缀，是因为展示handler 经过了 StripPrefixGatewayFilterFactory 这个过滤器的处理，原有的路由前缀被过滤掉了！

方案1，通过swagger 的host 配置手动维护一个前缀

return new Docket(DocumentationType.SWAGGER_2)
    .apiInfo(apiInfo())
    .host("主机名：端口：服务前缀")  //注意这里的主机名：端口是网关的地址和端口
    .select()
    .apis(RequestHandlerSelectors.withMethodAnnotation(ApiOperation.class))
    .paths(PathSelectors.any())
    .build()
    .globalOperationParameters(parameterList);

方案2，增加X-Forwarded-Prefix

swagger 在拼装URL 数据时候，会增加X-Forwarder-Prefix 请求头里面的信息为前缀

Spring Cloud Gateway 接口文档聚合实现
通过如上分析，知道应该在哪里下手了吧，在网关上追加一个请求头即可

@Component
public class SwaggerHeaderFilter extends AbstractGatewayFilterFactory {
    private static final String HEADER_NAME = "X-Forwarded-Prefix";

    @Override
    public GatewayFilter apply(Object config) {
        return (exchange, chain) -> {
            ServerHttpRequest request = exchange.getRequest();
            String path = request.getURI().getPath();
            if (!StringUtils.endsWithIgnoreCase(path, SwaggerProvider.API_URI)) {
                return chain.filter(exchange);
            }

            String basePath = path.substring(0, path.lastIndexOf(SwaggerProvider.API_URI));


            ServerHttpRequest newRequest = request.mutate().header(HEADER_NAME, basePath).build();
            ServerWebExchange newExchange = exchange.mutate().request(newRequest).build();
            return chain.filter(newExchange);
        };
    }
}