racker / salus-app-base

This is a Maven "pom" module that provides a simple, unified configuration for building Spring Boot application modules. This module references Spring Boot Starter Parent, so all application modules using this salus-app-base will transitively gain the same benefits of the Spring Boot parent.

Application POM Configuration

Parent reference

The typical way to reference this parent module is to add this to the application's pom.xml:

<parent>
    <groupId>com.rackspace.salus</groupId>
    <artifactId>salus-app-base</artifactId>
    <version>0.1.0-SNAPSHOT</version>
    <relativePath>../salus-app-base</relativePath>
</parent>

The relativePath is optional; however, the convention is to specify the relative path to the apps/salus-app-base directory of the Salus Telemetry Bundle repo

Main plugin config

The Spring Boot parent configures the spring-boot-maven-plugin; however, each application still needs to "activate" the plugin with at least the following plugin specification:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Docker build config

This app base module preconfigures the jib maven plugin; however, each application needs to "activate" the plugin to enable Docker image building by adding the following to the build>plugins section along with the spring-boot-maven-plugin mentioned above.

<build>
    <plugins>
        <!-- spring-boot-maven-plugin plugin would be here too-->
        <plugin>
            <groupId>com.google.cloud.tools</groupId>
            <artifactId>jib-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

By default, the jib plugin is configured to use an OpenJDK JRE Alpine base image; however, the base image (and other configuration) can be overridden by adding this type of <configuration> section within the <plugin>:

<configuration>
    <from>
        <!-- SHA can be obtained from https://console.cloud.google.com/gcr/images/distroless/GLOBAL/java?gcrImageListsize=50 -->
        <image>gcr.io/distroless/java@sha256:b430543bea1d8326e767058bdab3a2482ea45f59d7af5c5c61334cd29ede88a1</image>
    </from>
</configuration>

Usage

The included Maven plugins enable some standardized build/run behaviors for the applications that reference this parent.

Running applications via Maven

An application can be built and started from the command-line using:

mvn spring-boot:run

Application command-line arguments can be passed via spring-boot.run.arguments, such as

mvn spring-boot:run -Dspring-boot.run.arguments=--server.port=9999

Spring profiles can be activated via spring-boot.run.profiles, such as

mvn spring-boot:run -Dspring-boot.run.profiles=dev

More information about the configuration of the run goal can be found here.

Building local Docker images

Along with the usual Maven goals add jib:dockerBuild to also include a Docker image build, such as

mvn package jib:dockerBuild

NOTE this specific goal requires access to a Docker daemon, such as via Docker for Desktop or a mounted Docker socket.

Publishing Docker images to GCR

Use the preparation part of these docs to install the Cloud SDK tools and configure Docker for authentication. You can disregard the details about docker push since the Maven jib plugin will take of the equivalent operations.

Tip: on MacOS you can install the Cloud SDK using brew:

brew cask install google-cloud-sdk

In the application module, run the following replacing $PROJECT_ID with the Google Cloud project's ID, which is of the form of an identifer and number separated by a dash:

mvn -Ddocker.image.prefix=gcr.io/myapp-12345 jib:dockerBuild