Sometimes you want your pom.xml to do different things on localhost vs. when running on heroku.

Maven profiles, along with the Spring Boot *.properties files are one way to acheive this.

The code below, when added to a Maven pom.xml creates two different profiles called localhost and heroku:

Note that:

You can put a localhost.properties file in src/main/config/localhost that will override the shared properties in application.properties, and a heroku.properties in the src/main/config/heroku directory.
You can specify different dependencies, e.g. to use the H2 database on localhost, but postgres on heroku.
You can put a data.sql file in src/main/resources, but use these settings to control when it does and does not get loaded:
- In localhost.properties: spring.datasource.initialization-mode=always
- In heroku.properties: spring.datasource.initialization-mode=never

   <profiles>
        <profile>
            <id>localhost</id>
            <build>
                <resources>
                    <resource>
                        <directory>src/main/resources</directory>
                    </resource>
                    <resource>
                        <directory>src/main/config/localhost</directory>
                    </resource>
                </resources>
            </build>
            <dependencies>
                <dependency>
                    <groupId>com.h2database</groupId>
                    <artifactId>h2</artifactId>
                    <scope>runtime</scope>
                 </dependency>
            </dependencies>
        </profile>
        <profile>
            <id>heroku</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <build>
                <resources>
                    <resource>
                        <directory>src/main/resources</directory>
                    </resource>
                    <resource>
                        <directory>src/main/config/heroku</directory>
                    </resource>
                </resources>

            </build>
            <dependencies>
                <dependency>
                    <groupId>org.postgresql</groupId>
                    <artifactId>postgresql</artifactId>
                </dependency>

                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-jdbc</artifactId>
                </dependency>
            </dependencies>
        </profile>
    </profiles>

How can I tell which profile(s) is/are active?

This command tells you which profile(s) are active:

mvn help:active-profiles

How can I tell which profile(s) is/are active?

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