Cannot istantiate chaincode docker container due to missing Main method in contract class

Question

The chaincode container cannot start (after committing to the channel) due to the following error:

Error: Main method not found in class mypackage.MyChaincodeClass, please define the main method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

I'm working with fabric-java-chaincode 2.2.3 on a 2.2.2 network.

So the problem seems self explanatory but I'm using the example on Maven java chaincode on GitHub as a guideline and I adapted the maven shade plugin configuration:

 <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>3.1.0</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <finalName>chaincode</finalName>
                            <transformers>
                                <transformer                                    
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>mypackage.MyChaincodeClass</mainClass>
                                </transformer>
                            </transformers>
                            <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>

the tree of my project is the following:

.
└── project-repo/
    ├── chaincode/
    │   ├── src/
    │   │   └── main/
    │   │       └── java/
    │   │           └── mypackage/
    │   │               └── MyChaincodeClass.java
    │   └── pom.xml
    └── another-module/
        └── ...

I tried to start the uber-jar using java -jar chaincode.jar and I get the same error as the one printed in the container logs.

The manifest in the generate uber-jar looks good to me:

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven 3.6.3
Built-By: ultracode
Build-Jdk: 11.0.9
Main-Class: mypackage.MyChaincodeClass

The chaincode uses only the @Contract and @Transaction annotation and implements the ContractInterface interface (I'm not using the @Default annotation beacause this chaincode is not the default one in the channel)

ibrahimq21 · Answer 1 · 2022-08-17T12:28:28.320

0

you need to mention the complete directory from chaincode Example:

    <mainClass>chaincode.example.SimpleChaincode</mainClass>

edited Aug 17 '22 at 12:28

answered Aug 17 '22 at 11:47

ibrahimq21

3
4

Thanks for the answer but is unclear how this can solve the problem. My package structure and class name are different from the github example. The chaincode class `MyChaincodeClass` is located in the package `mypackage` so the complete path is `src/main/java/mypackage/MyChaincodeClass.java`. The pom file is at the same level as the `src` like any other vanilla maven project. – ultracode Aug 17 '22 at 12:44
yes you have two options one is you can change the directory structure to shorten it and two is to mention the complete package example: chaincode.src.main.java.mypackage.MyPackageClass – ibrahimq21 Aug 17 '22 at 12:47
hopefully it will resolve the current issue. – ibrahimq21 Aug 17 '22 at 12:49

ultracode · Accepted Answer · 2022-08-19T10:05:23.150

The maven-shade-plugin transformer configuration the mainClass tag must be set like this :

<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
   <mainClass>org.hyperledger.fabric.contract.ContractRouter</mainClass>
</transformer>

I was missled by the Maven example for the 2.2 release in which the maven shade plugin transformer is set like this:


<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
   <mainClass>chaincode.example.SimpleChaincode</mainClass>
</transformer>

In later versions the error was fixed, also the Gradle example in the same release has the correct setting.

Cannot istantiate chaincode docker container due to missing Main method in contract class

2 Answers2