Fixing SpringCloud's bootstrap.yml Not Recognizing the @activatedProperties@ Placeholder

In Spring projects we often use maven variables to switch environments — for example the @activatedProperties@ placeholder, passed in at maven packaging time so the config file can switch between runtime environments.

Today’s problem: in SpringCloud, a bootstrap.yml file used the @activatedProperties@ placeholder, but no matter how I rebuilt the package, it was never substituted — it ended up verbatim in the packaged artifact, and the application wouldn’t run.

Use Maven Filtering

Maven filtering is a feature of the Maven build process that dynamically replaces properties in files during the build.

For example, you can define a property in the project’s config and reference it in a file; during the build, Maven replaces the property with its actual value.

So we need to modify the build section of pom.xml and add filtering configuration:

<build>
    <finalName>${project.artifactId}</finalName>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.yml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Now Maven will replace properties in the file with their actual values during the build.

For more questions, the official docs are the best reference: https://maven.apache.org/plugins/maven-resources-plugin/examples/filter.html