How to solve a Camel3 fat-jar creation exception? - maven

Question

I use Apache Camel 3.18.2 witch camel-main. To create a fat-jar I configured the following two plugins within my pom.xml:
<plugin>
<groupId>org.apache.camel</groupId>
<artifactId>camel-maven-plugin</artifactId>
<version>3.18.2</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>prepare-fatjar</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>de.powerstat.camel.homeautomation.MainApp</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
As dependecies I have:
<dependencies>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-core</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-main</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-netty</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-stream</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-paho</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-quartz</artifactId>
</dependency>
<dependency>
<groupId>de.powerstat.camel.component</groupId>
<artifactId>camel-fbaha</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>de.powerstat.camel.component</groupId>
<artifactId>camel-fbtr64</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.openmuc</groupId>
<artifactId>jsml</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.18.0</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.18.0</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.18.0</version>
<scope>runtime</scope>
</dependency>
</dependencies>
But durin running mvn clean install I got:
[INFO] --- camel-maven-plugin:3.18.2:prepare-fatjar (default) # myhome ---
[INFO] Found 5 Camel type converter loaders from project classpath
[INFO]
[INFO] --- maven-assembly-plugin:2.2-beta-5:single (make-assembly) # myhome ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-assembly-plugin:2.2-beta-5:single (make-assembly) on project myhome: Error reading assemblies: No assembly descriptors found. -> [Help 1]
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
Exception in thread "ivy-httpclient-shutdown-handler" java.lang.NoClassDefFoundError:
org/apache/http/impl/conn/PoolingHttpClientConnectionManager$2
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.shutdown(PoolingHttpClientConnectionManager.java:413)
at org.apache.http.impl.client.HttpClientBuilder$2.close(HttpClientBuilder.java:1244)
at org.apache.http.impl.client.InternalHttpClient.close(InternalHttpClient.java:201)
at org.apache.ivy.util.url.HttpClientHandler.close(HttpClientHandler.java:357)
at org.apache.ivy.util.url.HttpClientHandler$1.run(HttpClientHandler.java:84)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.ClassNotFoundException: org.apache.http.impl.conn.PoolingHttpClientConnectionManager$2
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
... 6 more
That looks to me like this is an implicit dependency that have not been added by the camel-maven-plugin.
So my question is how to solve this problem?
I also tried to use the maven-shade-plugin instead of maven-assembly-plugin:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.4.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<createDependencyReducedPom>true</createDependencyReducedPom>
<filters>
<filter>
<artifact>*:*</artifact>
<excludes>
<exclude>META-INF/*.SF</exclude>
<exclude>META-INF/*.DSA</exclude>
<exclude>META-INF/*.RSA</exclude>
</excludes>
</filter>
</filters>
</configuration>
</execution>
</executions>
</plugin>
Which then results in a fat-jar with the following exception during executing it:
[ERROR] 2022-09-30T22:04:48,426 15612/22 org.apache.camel.processor.errorhandler.DefaultErrorHandler Failed delivery for (MessageId:
08B251E5AD78E72-0000000000000000 on ExchangeId:
08B251E5AD78E72-0000000000000000). Exhausted after
delivery attempt: 1 caught:
org.apache.camel.InvalidPayloadException: No body available of type: java.lang.Integer but has type:
java.lang.String on: Message. Caused by: No type converter available to convert from type: java.lang.String to the required type: java.lang.Integer. Exchange[]. Caused by:
[org.apache.camel.NoTypeConversionAvailableException - No type converter available to convert from type:
java.lang.String to the required type: java.lang.Integer]
So it looks the shade-plugin creates a fat-jar but missed something of camels dependencies.
Maybe this could be solved in one or the other way?
Last but not least the main question is how to create a Camel3 fat jar that is complete and works correctly?

Answer 1

Based on the error message
Error reading assemblies: No assembly descriptors found.
It looks like you are missing your assembly descriptor. You'll need to define a descriptor or descriptorRef
descriptor example:
<project>
[...]
<build>
[...]
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.4.2</version>
<configuration>
<descriptors>
<descriptor>src/assembly/src.xml</descriptor>
</descriptors>
</configuration>
[...]
</project>
descriptorRef example:
<project>
[...]
<build>
[...]
<plugins>
<plugin>
<!-- NOTE: We don't need a groupId specification because the group is
org.apache.maven.plugins ...which is assumed by default.
-->
<artifactId>maven-assembly-plugin</artifactId>
<version>3.4.2</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
[...]
</project>
If defining a descriptor, see the this about the descriptor format.