useful-dev-notes

Build Container Image without Manually writing a Dockerfile

1. edit pom.xml

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <excludes>
                    <exclude>
                        <groupId>org.projectlombok</groupId>
                        <artifactId>lombok</artifactId>
                    </exclude>
                </excludes>
                <!--add to plugin if already present-->
                <imageName>your-image-name</imageName>
                <!--prevents pulling of buildpack each time-->
                <pullPolicy>IF_NOT_PRESENT</pullPolicy>
                <layers>
                    <!--enable layers to make subsequent builds faster-->
                    <enabled>true</enabled>
                </layers>
            </configuration>
        </plugin>
    </plugins>
</build>

then

1. run

mvn -T 1C spring-boot:build-image -DskipTests
# skip test, (-T 1C) are optional

1. There is another approach to add custom layering useful when working with 2 types of dependencies e.g. external and internal
   • internal might change frequently and thus make the dependency layer built again and again which can be slow
2. Another way to do using JIB
   • Does not need docker installed
   • May sometimes produce sub-par imags as not specifically for spring apps