Multi-module maven microservices deploy to Heroku - docker

Question

I have a microservices project with a parent POM and all the other modules with an internal POM.
Locally, if I run mvn clean install -DskipTests everything works.
I want to deploy all the microservices to Heroku, how can i do this?
The project works also for Docker & Kubernetes, is there a way to integrate also Docker in Heroku?
So it will be beautiful if I can deploy all the microservices as 1 project in Heroku, with every microservices as a Docker image.
Thank you in advance!
This is an example of my project:
Parent POM:
<?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.petcare</groupId>
<artifactId>website-petcare-backend</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<name>parent-pom</name>
<modules>
<module>apiGateway</module>
<module>reservationService</module>
<module>userService</module>
<module>eurekaServer</module>
<module>mapService</module>
<module>authService</module>
</modules>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
<!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
<plugin>
<artifactId>maven-site-plugin</artifactId>
<version>3.7.1</version>
</plugin>
<plugin>
<artifactId>maven-project-info-reports-plugin</artifactId>
<version>3.0.0</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>

Answer 1

Build
You can build all images for the sub-modules using the docker-maven-plugin.
Each sub-module must have its own Dockerfile, then in the parent POM add:
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>docker-maven-plugin</artifactId>
<version>0.38.1</version>
<executions>
<execution>
<id>start</id>
<phase>pre-integration-test</phase>
<goals>
<goal>build</goal>
<goal>start</goal>
</goals>
</execution>
<execution>
<id>stop</id>
<phase>post-integration-test</phase>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
When running mvn clean package docker:build all projects are built and Dockerized
Deploy
Deploying all images (each image into its own web Dyno) is a little bit more complicated. You have few options:
Script from the command line: typically you can push the image with the following commands
heroku container:push web -a appname
heroku container:release web a appname
You could build a script that performs those steps for each and (very important) performs both the heroku login and heroku:container login using the credentials
Using heroku.yml where you can define at once all the containers to be deployed. It is a good approach but you need to git push your changes (see here)
Use CI/CD application like Github Actions. In this case your workflow compiles, tests, builds and pushes the application.
This is my preferred approach: you can decide when to build/deploy (on master push? manually?), you save the Heroku credentials as secrets, you can automate the release pipeline.
You can read more here
You can also try the Heroku Docker Maven plugin if you like to control all services using Maven