问题说明

Spring Boot 2.2.3 修复了 Spring Boot 2.2的大量问题，当升级至 2.2.3 以后，直接翻车 pigx-gateway 网关应用直接启动不起来。

翻车日志

***************************
APPLICATION FAILED TO START
***************************

Description:

An attempt was made to call a method that does not exist. The attempt was made from the following location:

    org.springframework.cloud.gateway.config.GatewayAutoConfiguration$NettyConfiguration.gatewayHttpClient(GatewayAutoConfiguration.java:597)

The following method did not exist:

    reactor.netty.resources.ConnectionProvider.elastic(Ljava/lang/String;Ljava/time/Duration;)Lreactor/netty/resources/ConnectionProvider;

The method's class, reactor.netty.resources.ConnectionProvider, is available from the following locations:

    jar:file:/Users/lengleng/env/repository/io/projectreactor/netty/reactor-netty/0.9.3.RELEASE/reactor-netty-0.9.3.RELEASE.jar!/reactor/netty/resources/ConnectionProvider.class

It was loaded from the following location:

    file:/Users/lengleng/env/repository/io/projectreactor/netty/reactor-netty/0.9.3.RELEASE/reactor-netty-0.9.3.RELEASE.jar


Action:

Correct the classpath of your application so that it contains a single, compatible version of reactor.netty.resources.ConnectionProvider

问题排查

如上日志涉及到 reactor-netty 依赖版本的问题

    +---------------------------+            +---------------------------+
    | Spring Boot 2.2.3.RELEASE |            | Spring Boot 2.2.2.RELEASE |
    +-------------+-------------+            +-------------+-------------+
                  |                                        |
+-----------------v----------------+     +-----------------v----------------+
|spring-boot-starter-reactor-netty |     |spring-boot-starter-reactor-netty |
|              2.2.3.RELEASE       |     |              2.2.2.RELEASE       |
+-----------------+----------------+     +-----------------+----------------+
                  |                                        |
          +-------+--------+                       +-------+--------+
          |  reactor-netty |                       |  reactor-netty |
          |  0.9.3.RELEASE |                       |  0.9.2.RELEASE |
          +----------------+                       +----------------+

`ConnectionProvider`

0.9.3 未对以下版本兼容，去掉ConnectionProvider.elastic(Ljava/lang/String;Ljava/time/Duration;) ，多态出来一个 maxLifeTime 的参数，具体参考
reactor/reactor-netty#922
reactor/reactor-netty#924

    /**
     * Create a {@link ConnectionProvider} to cache and grow on demand {@link Connection}.
     * <p>An elastic {@link ConnectionProvider} will never wait before opening a new
     * connection. The reuse window is limited but it cannot starve an undetermined volume
     * of clients using it.
     *
     * @param name the channel pool map name
     * @param maxIdleTime the {@link Duration} after which the channel will be closed when idle (resolution: ms),
     *                    if {@code NULL} there is no max idle time
     * @param maxLifeTime the {@link Duration} after which the channel will be closed (resolution: ms),
     *                    if {@code NULL} there is no max life time
     *
     * @return a new {@link ConnectionProvider} to cache and grow on demand
     * {@link Connection}
     */
    static ConnectionProvider elastic(String name, @Nullable Duration maxIdleTime, @Nullable Duration maxLifeTime) {
      ...
    }

解决方法

全局使用 0.9.4 暂时是快照版本，或者降级到 0.9.2 ，Spring Boot 2.2.3 未修改reactor 问题，降级是目前最好的选择。

<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>io.projectreactor.netty</groupId>
                <artifactId>reactor-netty</artifactId>
                <version>0.9.2.RELEASE</version>
            </dependency>
        </dependencies>
    </dependencyManagement>