Why isn't spring.config.import overridden by environment variables in my Spring Boot 3 microservices?

When using Spring Boot 3 with the new import mechanism (spring.config.import), that property is processed during the bootstrap phase. The bootstrap phase happens before the normal environment properties (like those provided via Docker Compose’s environment block or Kubernetes config) are merged, so your override isn’t taking effect.

Why the Override Doesn’t Work

• Early Evaluation: The spring.config.import property is evaluated very early on (during application startup bootstrap) – even before the normal environment properties are loaded. This means that any modifications done later (at the environment level) are too late.
• Order of Precedence: Docker Compose (and Kubernetes) environment variables are applied in a property source that comes after bootstrap configuration. The property you specify in your local application.properties (i.e. spring.config.import) has already been processed.
• Immutable Bootstrap Context: Since the config import is processed to bootstrap the application context, it does not honor overrides from sources that are merged after the bootstrap phase.

Workarounds

• Pass as a Command-Line Argument or System Property: One way to ensure your override happens early enough is to set the property using a command-line argument or a system property (using -DSPRING_CONFIG_IMPORT=configserver:http://config:8888). This way, the override is available during the bootstrap phase.
• Use a Bootstrap Configuration File: Alternatively, you can use a dedicated bootstrap.properties (or bootstrap.yml) file. Properties in this file are processed during the bootstrap phase and thus can override defaults defined in application.properties.

Example

Here’s an example of passing the parameter as a command-line argument (or you can set it as an environment variable that the JVM recognizes at startup):

BASHCopied
docker run -e JAVA_OPTS="-Dspring.config.import=configserver:http://config:8888" be-image:0.0.1

Or if using Docker Compose, modify the command section:

YAMLCopied
be:
  image: be-image:0.0.1
  container_name: be-container
  build:
    context: ./springcloud-fe-thymeleaf-be-springboot-db-sql-mysql-config_BE
    dockerfile: Dockerfile
  depends_on:
    config:
      condition: service_healthy
  ports:
    - "8081:8081"
  command: >
    java -Dspring.config.import=configserver:http://config:8888
         -jar your-app.jar
  healthcheck:
    test: ["CMD", "curl", "-f", "http://localhost:8081/actuator/health"]
    interval: 10s
    timeout: 10s
    retries: 5
    start_period: 10s
  networks:
    - helloworld-network

This ensures that the property is available when the bootstrap context is loaded.

Summary

The key point is that spring.config.import is handled during the bootstrap phase, which prevents later environment overrides (from Docker Compose or Kubernetes) from taking effect. Use command-line parameters or a bootstrap file to override this property early enough in the application startup process.