Spring boot with Zuul proxy crashes on Maven, while Gradle works

Question

I have a Spring boot project which is built with Gradle.

I need to migrate it to Maven, which I thought would be easy (should be), but I've encountered an issue in the Zuul depedency, or to be exact: spring-cloud-starter-zuul.

When I run the Spring boot application with the annotation @EnableZuulProxy it produces the following error:

2017-03-30 00:02:57.521  WARN 11380 --- [ost-startStop-1] c.n.c.sources.URLConfigurationSource     : No URLs will be polled as dynamic configuration sources.
2017-03-30 00:02:57.521  INFO 11380 --- [ost-startStop-1] c.n.c.sources.URLConfigurationSource     : To enable URLs as dynamic configuration sources, define System property archaius.configurationSource.additionalUrls or make config.properties available on classpath.
2017-03-30 00:02:57.532  INFO 11380 --- [ost-startStop-1] c.netflix.config.DynamicPropertyFactory  : DynamicPropertyFactory is initialized with configuration sources: com.netflix.config.ConcurrentCompositeConfiguration@df85e3e
2017-03-30 00:02:57.556 ERROR 11380 --- [ost-startStop-1] o.s.b.c.embedded.tomcat.TomcatStarter    : Error starting Tomcat context. Exception: org.springframework.beans.factory.UnsatisfiedDependencyException. Message: Error creating bean with name 'org.springframework.cloud.netflix.zuul.ZuulConfiguration$ZuulFilterConfiguration': Unsatisfied dependency expressed through field 'filters'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'simpleHostRoutingFilter' defined in org.springframework.cloud.netflix.zuul.ZuulProxyConfiguration: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.netflix.zuul.filters.route.SimpleHostRoutingFilter]: Factory method 'simpleHostRoutingFilter' threw exception; nested exception is java.lang.NoClassDefFoundError: org/apache/http/conn/HttpClientConnectionManager
2017-03-30 00:02:57.588  WARN 11380 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat
2017-03-30 00:02:57.588 ERROR 11380 --- [           main] o.s.boot.SpringApplication               : Application startup failed

The error only occurs on the Maven build, which narrow the problem to the pom.xml file vs build.gradle which does run.

After tinkering with the working build.gradle file, I've managed to produce the error when commenting out this part:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.4.3.RELEASE")
    }
}
apply plugin: 'org.springframework.boot'

So the issue is I don't use the plugin in my maven file?

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>aaa</groupId>
    <artifactId>helloZuul</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>1.4.3.RELEASE</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-io -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-zuul -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
            <version>1.2.6.RELEASE</version>
        </dependency>
    </dependencies>
</project>

build.gradle

group 'aaa'
version '1.0-SNAPSHOT'

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.4.3.RELEASE")
    }
}

apply plugin: 'java'
apply plugin: 'idea'
apply plugin: 'org.springframework.boot'
apply plugin: 'war'

sourceCompatibility = 1.8

jar {
    baseName = 'gs-rest-service'
    version = '0.1.0'
}

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile "org.springframework.boot:spring-boot-starter-web:1.4.3.RELEASE"
    compile group: 'org.apache.commons', name: 'commons-io', version: '1.3.2'
    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-zuul', version: '1.2.6.RELEASE'
}

How can I make my maven project run? Or more specifically, what is the purpose of the spring boot gradle plugin?

Any help will be greatly appreciated!

Answer 1

I managed to get it working after a lot of trial and error.

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>aaa</groupId>
    <artifactId>client</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-io -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Brixton.SR5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

Answer 2

You need to add dependency management in your pom.xml like below.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Camden.SR6</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>