IntelliJ and Maven shader plugin with multiple modules - maven

Question

I'm trying to build a fat jar witht he maven shader plugin. I am going a bit in circles fixing maven and breaking IntelliJ build, and viceversa.
My project is as follows (I left out the plugin section, which contains the shader plugin):
module-a - main project module, contains main class
module-b - module, used by A
module-c - module, used by A
module A pom:
http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.0.0
<groupId>com.my</groupId>
<artifactId>module-a</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>../module-b</module>
<module>../module-c</module>
</modules>
<dependencies>
<dependency>
<groupId>com.my</groupId>
<artifactId>module-b</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.my</groupId>
<artifactId>module-c</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.clapper</groupId>
<artifactId>grizzled-slf4j_2.11</artifactId>
<version>1.0.2</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.7</version>
</dependency>
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-http-experimental_2.11</artifactId>
<version>2.0.3</version>
</dependency>
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-http-core-experimental_2.11</artifactId>
<version>2.0.3</version>
</dependency>
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-stream-experimental_2.11</artifactId>
<version>2.0.3</version>
</dependency>
<dependency>
<groupId>net.ceedubs</groupId>
<artifactId>ficus_2.11</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>com.typesafe</groupId>
<artifactId>config</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.3</version>
</dependency>
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-actor_2.11</artifactId>
<version>2.4.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.5</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<shadedClassifierName>allinone</shadedClassifierName>
<artifactSet>
<includes>
<include>*:*</include>
</includes>
</artifactSet>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>reference.conf</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<manifestEntries>
<Main-Class>com.my.Service</Main-Class>
</manifestEntries>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
module B and C poms are similar(except for the module names)
<?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.my</groupId>
<artifactId>module-b</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<dependencies>
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-actor_2.11</artifactId>
<version>2.4.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
All modules are in the same directory at the same level. Although I can build via IntelliJ just fine, I cannot build module-a via maven, because it cannot find modules -b and -c. So in general, I can't build anything that references a local project, since Maven won't find them. Doesn't matter if I try it inside the IDE or from the command line.
Building module-a I get:
[ERROR] Failed to execute goal on project module-a: Could not resolve
dependencies for project com.my:module-a:pom:1.0-SNAPSHOT: The
following artifacts could not be resolved:
com.my:module-b:jar:1.0-SNAPSHOT, com.my:module-c:jar:1.0-SNAPSHOT:
Could not find artifact com.my:module-c:jar:1.0-SNAPSHOT -> [Help 1]
I realize I probably screwed up these poms, trying to play with dependencies vs. module references, but what is the proper way to reference a local module in a pom file, without having to install the module in a repository?
I read that I should be creating a fourth parent project which has module-a as parent, and use that project to create the shaded jar, but even with that approach, I'm failing to get it to locate modules in the same project, it only resolves repo modules.

Answer 1

<packaging>pom</packaging>
<modules>
<module>../module-b</module>
<module>../module-c</module>
</modules>
this part of your module-a's pom reflects that it is the parent of module-b and module-c but contrarily your module-b and c are missing the
<parent>
<groupId>com.my</groupId>
<artifactId>module-a</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
Just an understanding, your module's pom shall include those dependencies which you might want to use as a library for the same. So I hope you want to use some code from module-b/c on your module-a to include them in your pom dependencies.
Or you may want to remove these lines from your module-a
<modules>
<module>../module-b</module>
<module>../module-c</module>
</modules>
considering all the modules are independent of each other in terms of hierarchy.