Maven shade plugin can not find 'mainClass' exception?

Question

There are a very strange build with maven-shade-plugin:2.4.3 in a standard maven project. It was throw can not find mainClass exception always when execute maven package command. I just simulate an maven-shade-plugin example, see below:

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mkyong.core.utils</groupId>
    <artifactId>dateUtils</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>dateUtils</name>
    <url>http://maven.apache.org</url>

    <properties>
        <jdk.version>1.7</jdk.version>
        <jodatime.version>2.5</jodatime.version>
        <junit.version>4.11</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>${jodatime.version}</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>dateutils</finalName>

        <resources>
            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>
        <plugins>

            <!-- download source code in Eclipse, best practice -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.9</version>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>false</downloadJavadocs>
                </configuration>
            </plugin>

            <!-- Set a compiler level -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                </configuration>
            </plugin>

            <!-- Maven Shade Plugin -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <executions>
                    <!-- Run shade goal on package phase -->
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
          </execution>
                </executions>
        <configuration>
            <shadedArtifactAttached>true</shadedArtifactAttached>
            <shadedClassifierName>jar-with-dependencies</shadedClassifierName>
            <filters>
                <filter>
                    <artifact>*:*</artifact>
                    <excludes>
                        <exclude>META-INF/*.SF</exclude>
                        <exclude>META-INF/*.DSA</exclude>
                        <exclude>META-INF/*.RSA</exclude>
                    </excludes>
                </filter>
            </filters>
            <transformers>
              <transformer
                      implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                  <mainClass>com.mkyong.core.utils.App</mainClass>
              </transformer>
          </transformers>
        </configuration>

            </plugin>

        </plugins>
    </build>

</project>

This one can run success. Then just change the main Class name, and other like this:

<plugin>
     <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
                <configuration>
                    <transformers>
                        <transformer
                                implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                            <mainClass>xxxxxxx</mainClass>
                        </transformer>
                    </transformers>
                </configuration>
            </plugin>

the parent pom.xml file about the plugin line:

<pluginManagement>
    <plugins>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>2.4.3</version>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <shadedArtifactAttached>true</shadedArtifactAttached>
                <shadedClassifierName>jar-with-dependencies</shadedClassifierName>
                <filters>
                    <filter>
                        <artifact>*:*</artifact>
                        <excludes>
                            <exclude>META-INF/*.SF</exclude>
                            <exclude>META-INF/*.DSA</exclude>
                            <exclude>META-INF/*.RSA</exclude>
                        </excludes>
                    </filter>
                </filters>
            </configuration>
        </plugin>
    </plugins>

</pluginManagement>

So the modules will extends parent, but when package it throws exception, said:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:2.4.3:shade (default) on project analytics-sdk-storm-local: Unable to parse configuration of mojo org.apache.maven.plugins:maven-shade-plugin:2.4.3:shade for parameter mainClass: Cannot find 'mainClass' in class org.apache.maven.plugins.shade.resource.AppendingTransformer -> [Help 1]

But why it was happened.There are the maven dependencies tree show:

[INFO] --- maven-dependency-plugin:2.10:tree (default-cli) @ xxxxx ---
[INFO] local:jar:1.0.1-SNAPSHOT
[INFO] +- org.apache.kafka:kafka_2.10:jar:0.8.1.1:compile
[INFO] |  +- com.yammer.metrics:metrics-core:jar:2.2.0:compile
[INFO] |  +- org.xerial.snappy:snappy-java:jar:1.1.2:compile
[INFO] |  +- net.sf.jopt-simple:jopt-simple:jar:3.2:compile
[INFO] |  +- org.scala-lang:scala-library:jar:2.10.1:compile
[INFO] |  \- com.101tec:zkclient:jar:0.3:compile
[INFO] +- org.apache.storm:storm-core:jar:0.9.3:provided
[INFO] |  +- org.clojure:clojure:jar:1.5.1:provided
[INFO] |  +- clj-time:clj-time:jar:0.4.1:provided
[INFO] |  +- joda-time:joda-time:jar:2.8.2:provided
[INFO] |  +- compojure:compojure:jar:1.1.3:provided
[INFO] |  +- org.clojure:core.incubator:jar:0.1.0:provided
[INFO] |  +- org.clojure:tools.macro:jar:0.1.0:provided
[INFO] |  +- clout:clout:jar:1.0.1:provided
[INFO] |  +- ring:ring-core:jar:1.1.5:provided
[INFO] |  +- commons-fileupload:commons-fileupload:jar:1.3.1:provided
[INFO] |  +- javax.servlet:servlet-api:jar:2.5:provided
[INFO] |  +- hiccup:hiccup:jar:0.3.6:provided
[INFO] |  +- ring:ring-devel:jar:0.3.11:provided
[INFO] |  +- clj-stacktrace:clj-stacktrace:jar:0.2.2:provided
[INFO] |  +- ring:ring-jetty-adapter:jar:0.3.11:provided
[INFO] |  +- ring:ring-servlet:jar:0.3.11:provided
[INFO] |  +- org.mortbay.jetty:jetty:jar:6.1.26:provided
[INFO] |  +- org.mortbay.jetty:jetty-util:jar:6.1.26:provided
[INFO] |  +- org.clojure:tools.logging:jar:0.2.3:provided
[INFO] |  +- org.clojure:math.numeric-tower:jar:0.0.1:provided
[INFO] |  +- org.clojure:tools.cli:jar:0.2.4:provided
[INFO] |  +- commons-io:commons-io:jar:2.4:provided
[INFO] |  +- org.apache.commons:commons-exec:jar:1.1:provided
[INFO] |  +- commons-lang:commons-lang:jar:2.5:provided
[INFO] |  +- com.googlecode.json-simple:json-simple:jar:1.1.1:provided
[INFO] |  |  \- junit:junit:jar:4.12:provided
[INFO] |  |     \- org.hamcrest:hamcrest-core:jar:1.3:provided
[INFO] |  +- com.twitter:carbonite:jar:1.4.0:provided
[INFO] |  +- com.esotericsoftware.kryo:kryo:jar:2.21:provided
[INFO] |  +- com.esotericsoftware.reflectasm:reflectasm:jar:shaded:1.07:provided
[INFO] |  +- org.ow2.asm:asm:jar:4.0:compile
[INFO] |  +- com.esotericsoftware.minlog:minlog:jar:1.2:provided
[INFO] |  +- org.objenesis:objenesis:jar:1.2:compile
[INFO] |  +- com.twitter:chill-java:jar:0.3.5:provided
[INFO] |  +- org.yaml:snakeyaml:jar:1.16:provided
[INFO] |  +- commons-logging:commons-logging:jar:1.1.3:provided
[INFO] |  +- commons-codec:commons-codec:jar:1.9:provided
[INFO] |  +- com.googlecode.disruptor:disruptor:jar:2.10.1:provided
[INFO] |  +- org.jgrapht:jgrapht-core:jar:0.9.0:provided
[INFO] |  +- ch.qos.logback:logback-classic:jar:1.1.5:provided
[INFO] |  +- ch.qos.logback:logback-core:jar:1.0.13:provided
[INFO] |  +- org.slf4j:slf4j-api:jar:1.7.12:compile
[INFO] |  +- org.slf4j:log4j-over-slf4j:jar:1.7.16:provided
[INFO] |  \- jline:jline:jar:2.11:compile
[INFO] +- org.apache.storm:storm-kafka:jar:0.9.3:compile
[INFO] |  \- org.apache.curator:curator-framework:jar:2.5.0:compile
[INFO] |     +- org.apache.curator:curator-client:jar:2.5.0:compile
[INFO] |     +- org.apache.zookeeper:zookeeper:jar:3.4.6:compile
[INFO] |     |  \- io.netty:netty:jar:3.7.0.Final:compile
[INFO] |     \- com.google.guava:guava:jar:19.0:compile
[INFO] +- so.sao.analytics:analytics-sdk-common:jar:1.0.1-SNAPSHOT:compile
[INFO] |  +- com.esotericsoftware:kryo:jar:3.0.3:compile
[INFO] |  |  +- com.esotericsoftware:reflectasm:jar:1.10.1:compile
[INFO] |  |  \- com.esotericsoftware:minlog:jar:1.3.0:compile
[INFO] |  \- org.mapdb:mapdb:jar:2.0-beta12:compile
[INFO] \- so.sao.analytics:analytics-sdk-storm-common:jar:1.0.1-SNAPSHOT:compile

I real don't known why it was failed. Now just annotation the code. Is you had meet this one, show me, thanks.

Answer 1

I had this same issue. Turned out it was caused by some config Spring Boot brings in. I am using spring-boot-starter-parent as my parent pom.

I resolved the issue by setting the start-class property and removing the ManifestResourceTransformer configuration from the shade plugin in my pom.xml.

<properties>
  <start-class>package.Main</start-class>
</properties>

I found this property by searching the effective pom for ManifestResourceTransformer.