How to Shrink Spring Boot Microservices to 30 MB with Spring Native

Introduction

When deploying a Spring Cloud Alibaba microservice project with seven services on a single Alibaba Cloud server (2 CPU, 4 GB), each Spring Boot fat‑jar consumes about 500 MB, and additional components such as Nacos, Redis, Sentinel, RocketMQ, and ELK consume over 2 GB, leaving insufficient memory for the services.

Initial JVM tuning was applied:

# JVM initial heap size (-Xms) defaults to 1/64 of physical memory
-Xms128m
# JVM maximum heap size (-Xmx) defaults to 1/4 of physical memory
-Xmx128m
# Thread stack size (-Xss) typically 256 k
-Xss256k
# Parallel GC threads (usually equal to CPU cores)
-XX:ParallelGCThreads=2

When free heap drops below 40 %, the JVM expands the heap up to -Xmx; when free heap exceeds 70 %, it shrinks toward -Xms. Setting -Xms and -Xmx equal avoids heap resizing after each GC.

Even after tuning, memory usage remained around 100‑200 MB per service, far from the desired tens of megabytes.

Why Spring Native?

Spring Native leverages GraalVM native image compilation to produce lightweight native executables, improving Java’s competitiveness in cloud‑native environments. Officially, a Spring Native image containing Spring Boot, Spring MVC, Jackson, and Tomcat is about 50 MB.

Benefits observed:

Application startup in milliseconds.

Runtime memory consumption dramatically lower (≈50 MB).

Longer build time (a simple Hello World may take ~2 minutes).

Practical Guide

Environment

OS: Windows 10 21H1

IDE: IntelliJ IDEA 2021.2.3

JDK: graalvm‑ce‑java11‑21.3.0

Maven: 3.6.3

Docker Desktop for Windows: 20.10.12

Spring Boot: 2.6.2

Spring Native: 0.11.1

1. Install GraalVM

Download from https://www.graalvm.org/downloads/ and set JAVA_HOME to the GraalVM directory.

2. Install native‑image

gu install native-image

If the command fails, manually download the installer JAR from GitHub , extract, and run gu install -L native-image* in the bin folder.

3. Configure Maven (pom.xml)

A minimal pom.xml for Spring Native:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.2</version>
    </parent>
    <groupId>ltd.pcdd</groupId>
    <artifactId>spring-native</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <properties>
        <java.version>11</java.version>
        <spring-native.version>0.11.1</spring-native.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.experimental</groupId>
            <artifactId>spring-native</artifactId>
            <version>${spring-native.version}</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.experimental</groupId>
                <artifactId>spring-aot-maven-plugin</artifactId>
                <version>0.11.1</version>
                <executions>
                    <execution>
                        <id>generate</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <image>
                        <builder>paketobuildpacks/builder:tiny</builder>
                        <env>
                            <BP_NATIVE_IMAGE>true</BP_NATIVE_IMAGE>
                            <BPE_APPEND_JAVA_TOOL_OPTIONS>-Xms128m</BPE_APPEND_JAVA_TOOL_OPTIONS>
                            <BPE_APPEND_JAVA_TOOL_OPTIONS>-Xmx128m</BPE_APPEND_JAVA_TOOL_OPTIONS>
                            <BPE_APPEND_JAVA_TOOL_OPTIONS>-Xss256k</BPE_APPEND_JAVA_TOOL_OPTIONS>
                            <BPE_APPEND_JAVA_TOOL_OPTIONS>-XX:ParallelGCThreads=2</BPE_APPEND_JAVA_TOOL_OPTIONS>
                        </env>
                    </image>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-release</id>
            <url>https://repo.spring.io/release</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-release</id>
            <url>https://repo.spring.io/release</url>
        </pluginRepository>
    </pluginRepositories>
</project>

4. Build the native image

Run the following Maven commands (skip tests to speed up):

mvn clean
mvn -Dmaven.test.skip=true spring-boot:build-image

The build process consumes high CPU and memory but finishes successfully, producing a Docker image named spring-native.

5. Run the container

List images, then create and start a container: docker run -p 8080:8080 spring-native Docker Desktop shows the application starts in about 59 ms and uses roughly 28 MB of RAM.

6. Comparison

Without Spring Native, the same Spring Boot application starts in ~3 seconds and consumes ~511 MB of RAM.

Conclusion

Using Spring Native with GraalVM and Spring Boot Buildpacks can dramatically reduce startup time to the millisecond level and cut memory usage to tens of megabytes, making it suitable for resource‑constrained environments. For production use, refer to the latest official Spring Native documentation.