in my pom.xml I replaced this dependency:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
by
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
However, my Spring Boot application is still run as a traditional "web" application, and reactive parts do not work (e.g. a class implementing org.springframework.web.server.WebFilter is never called).
I run the app like this:
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
This answer https://stackoverflow.com/a/51378560 says you can force your Spring Boot app to be run as Reactive by doing this:
SpringApplication.setWebApplicationType(WebApplicationType.REACTIVE)
Unfortunately the setWebApplicationType() method is not static.
So I browsed through the Spring Boot code and found out the webApplicationType is determined via calls to the methods in the enum org.springframework.boot.WebApplicationType.
In my case, the static WebApplicationType deduceFromClasspath() method continues to return WebApplicationType.SERVLET; because in the first test of the method:
if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)
&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null))
ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null) evaluates to true which make the whole predicate fails.
So I wonder, why is the WEBMVC_INDICATOR_CLASS (value = org.springframework.web.servlet.DispatcherServlet) still present??? Well, mvn dependency:tree gives me the anwser:
[INFO] +- org.springframework.boot:spring-boot-starter-webflux:jar:2.1.8.RELEASE:compile
[INFO] | +- org.springframework:spring-web:jar:5.1.9.RELEASE:compile
[INFO] | \- org.springframework:spring-webflux:jar:5.1.9.RELEA4SE:compile
The spring-boot-starter-webflux dependency actually imports both!!!
So how I am supposed to do?!!
Exclude the spring-web?
Edit: as requested, added the full (redacted) pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.company</groupId>
<artifactId>whatever-backend-api</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Whatever API</name>
<description>API for whatever project</description>
<url>https://api.company.com/</url>
<organization>
<name>Company</name>
<url>http://www.company.com/</url>
</organization>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.8.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
<kotlin.version>1.3.10</kotlin.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<project.scm.id>gitRepo</project.scm.id>
<spring-cloud.version>Greenwich.SR3</spring-cloud.version>
<springfox.version>2.9.2</springfox.version>
<graphql-spring-boot-starter.version>5.10.0</graphql-spring-boot-starter.version>
</properties>
<distributionManagement>
<repository>
<id>releasesRepo</id>
<url>https://nexus.company.com/repository/maven-releases/</url>
</repository>
<snapshotRepository>
<uniqueVersion>false</uniqueVersion>
<id>snapshotsRepo</id>
<url>https://nexus.company.com/repository/maven-snapshots/</url>
</snapshotRepository>
</distributionManagement>
<scm>
<developerConnection>scm:git:https://gitlab.company.com/root/dev/whatever/whatever-backend-api.git</developerConnection>
<tag>HEAD</tag>
</scm>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-commons</artifactId>
</dependency>
<dependency>
<groupId>com.kastkode</groupId>
<artifactId>springsandwich</artifactId>
<version>1.0.2</version>
</dependency>
<dependency>
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.graphql-java-kickstart</groupId>
<artifactId>graphql-spring-boot-starter</artifactId>
<version>${graphql-spring-boot-starter.version}</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>${springfox.version}</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>${springfox.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>4.4</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.graphql-java-kickstart</groupId>
<artifactId>graphql-spring-boot-starter-test</artifactId>
<version>${graphql-spring-boot-starter.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<finalName>whatever-api</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>build-info</goal>
</goals>
<configuration>
<additionalProperties>
<java.source>${java.version}</java.source>
<encoding.source>${project.build.sourceEncoding}</encoding.source>
<encoding.reporting>${project.reporting.outputEncoding}</encoding.reporting>
</additionalProperties>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.jacoco</groupId>
<artifactId>jacoco-maven-plugin</artifactId>
<version>0.8.4</version>
<configuration>
<excludes>
<exclude>*MethodAccess</exclude>
</excludes>
</configuration>
<executions>
<execution>
<id>prepare-agent</id>
<goals>
<goal>prepare-agent</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-release-plugin</artifactId>
<configuration>
<tagNameFormat>@{project.version}</tagNameFormat>
</configuration>
</plugin>
</plugins>
</build>
</project>
