Spring Native实战(畅快体验79毫秒启动springboot应用)-原创手记-慕课网

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github.com/zq2599/blog_demos

内容：所有原创文章分类汇总及配套源码，涉及Java、Docker、Kubernetes、DevOPS等；

关于Spring Native

[Spring官方博客]于2021年03月11日宣布Spring Native的beta版本发布，借助Spring Native可以将spring应用与GraalVM集成到native image中；
native image是GraalVM的一项技术，会将java应用的字节码编译成可执行文件，还会与JDK的本地库做静态链接，运行应用时无需Java虚拟机，自身已集成了内存管理，线程调度等能力，更多信息请参考：www.graalvm.org/reference-manual/native-image/
本文以实战为主，因此不会用太多篇幅介绍Spring Native的理论和优势，这里简单小结几个重要特性：

应用启动速度不超过100毫秒；
启动即达到性能峰值（C1、C2等手段已经用不上了）
运行时更低的内存消耗；
docker镜像不含JDK（所需文件已经抽取出来放入镜像），官方展示的含有Spring Boot, Spring MVC, Jackson, Tomcat的镜像大小是50M；
为了达到前面的效果，代价是构建时间更长；

Spring Native到底是什么

个人的理解：Spring Native是Spring提供的、制作native image的技术方案，涉及到以下关键技术：

Spring ahead-of-time (AOT) 插件，对spring应用做AOT处理，使得传统虚拟机的class lazy loading在不复存在；
spring-boot-maven-plugin插件在构建docker镜像的时候，使用了名为dmikusa/graalvm-tiny的镜像作为构建工具，这个工具负责将当前工程的构建结果和GraalVM集成在一起，最终制作成native image；

本篇概览

作为实战风格的文章，本篇主要内容是开发springboot应用再构建为native image，然后验证其功能和效果，本文由以下内容构成：

环境信息
新建名为spring-native-tutorials的maven父工程，对实战用到的依赖库、插件等做统一配置；
新建名为webmvc的maven子工程，这是个springboot应用；
将webmvc构建为native image，这是个docker镜像；
在docker中启动镜像，验证是否可用，并检查相关相关指标；

环境信息

本次实战相关的环境信息如下：

电脑：MacBook pro 13寸 2018
操作系统：macOS Big Sur 11.2.3
IDE：IntelliJ IDEA 2018.3.5 (Ultimate Edition)
docker：20.10.5
JDK：1.8.0_211
maven：3.6.0
springboot：2.5.0-SNAPSHOT
spring-aot-maven-plugin：0.10.0-SNAPSHOT

源码下载

本篇实战中的完整源码可在GitHub下载到，地址和链接信息如下表所示(github.com/zq2599/blog_demos)：

名称	链接	备注
项目主页	github.com/zq2599/blog_demos	该项目在GitHub上的主页
git仓库地址(https)	github.com/zq2599/blog_demos.git	该项目源码的仓库地址，https协议
git仓库地址(ssh)	git@github.com:zq2599/blog_demos.git	该项目源码的仓库地址，ssh协议

这个git项目中有多个文件夹，本次实战的源码在spring-native-tutorials文件夹下，如下图红框所示：

在这里插入图片描述

新建名为spring-native-tutorials的maven父工程

对Spring Native的学习不是写出helloworld就完事，因此这里先创建一个父工程，为今后所有的应用提供统一的依赖库、插件管理；
新建名为spring-native-tutorials的maven父工程，pom.xml内容如下，有几处要注意的地方稍后提到：

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <modules>
        <module>webmvc</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.0-SNAPSHOT</version>
        <relativePath/>
    </parent>

    <groupId>com.bolingcavalry</groupId>
    <artifactId>spring-native-tutorials</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>pom</packaging>

    <properties>
        <java.version>1.8</java.version>
        <!-- springboot生成jar文件的文件名后缀，用来避免Spring Boot repackaging和native-image-maven-plugin插件之间可能存在的冲突 -->
        <classifier/>

        <!-- 构建镜像时的定制参数 -->
        <native.build.args/>

        <!-- 指定使用dmikusa/graalvm-tiny这个镜像作为构建工具，来构建镜像 -->
        <builder>dmikusa/graalvm-tiny</builder>

        <!-- spring cloud版本 -->
        <spring-cloud.version>2020.0.2</spring-cloud.version>
    </properties>

    <!-- 插件管理 -->
    <pluginRepositories>
        <pluginRepository>
            <id>spring-release</id>
            <name>Spring release</name>
            <url>https://repo.spring.io/release</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
        <pluginRepository>
            <id>spring-milestone</id>
            <name>Spring milestone</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
        <pluginRepository>
            <id>spring-snapshot</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <releases>
                <enabled>false</enabled>
            </releases>
        </pluginRepository>
    </pluginRepositories>

    <!--仓库管理-->
    <repositories>
        <repository>
            <id>spring-release</id>
            <name>Spring release</name>
            <url>https://repo.spring.io/release</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>spring-milestone</id>
            <name>Spring milestone</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>spring-snapshot</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <releases>
                <enabled>false</enabled>
            </releases>
        </repository>
    </repositories>

    <!--依赖包版本管理-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.experimental</groupId>
                <artifactId>spring-native</artifactId>
                <version>0.10.0-SNAPSHOT</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <!--插件配置-->
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <classifier>${classifier}</classifier>
                        <image>
                            <builder>${builder}</builder>
                            <env>
                                <BP_NATIVE_IMAGE>true</BP_NATIVE_IMAGE>
                                <BP_NATIVE_IMAGE_BUILD_ARGUMENTS>${native.build.args}</BP_NATIVE_IMAGE_BUILD_ARGUMENTS>
                            </env>
                            <!--执行构建任务的镜像，如果在当前环境不存在才会远程下载-->
                            <pullPolicy>IF_NOT_PRESENT</pullPolicy>
                        </image>
                    </configuration>
                </plugin>

                <!-- aot插件，ahead-of-time transformations -->
                <plugin>
                    <groupId>org.springframework.experimental</groupId>
                    <artifactId>spring-aot-maven-plugin</artifactId>
                    <version>0.10.0-SNAPSHOT</version>
                    <executions>
                        <execution>
                            <id>test-generate</id>
                            <goals>
                                <goal>test-generate</goal>
                            </goals>
                        </execution>
                        <execution>
                            <id>generate</id>
                            <goals>
                                <goal>generate</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

上述pom.xml有以下几处需要注意：

插件仓库、依赖库仓库、依赖库版本的配置都集中在这里；
配置好spring-aot-maven-plugin和spring-boot-maven-plugin这两个插件，子工程会用到；
spring-boot-maven-plugin插件制作docker镜像的时候，又会用到dmikusa/graalvm-tiny镜像，这才是真正构建native image的工具；

新建springboot类型的maven子工程

新建名为webmvc的子工程，pom.xml内容如下，可见内容很简单，就是常规依赖库和父工程配置的两个插件，一个负责执行AOT，一个负责构建镜像：

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>spring-native-tutorials</artifactId>
        <groupId>com.bolingcavalry</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>webmvc</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.experimental</groupId>
            <artifactId>spring-native</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.apache.tomcat.embed</groupId>
                    <artifactId>tomcat-embed-core</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.apache.tomcat.embed</groupId>
                    <artifactId>tomcat-embed-websocket</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.experimental</groupId>
            <artifactId>tomcat-embed-programmatic</artifactId>
            <version>${tomcat.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.experimental</groupId>
                <artifactId>spring-aot-maven-plugin</artifactId>
                <configuration>
                    <removeSpelSupport>true</removeSpelSupport>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

代码很简单，一个普通的springboot应用，带http接口：

package com.bolingcavalry.webmvc;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
import java.time.LocalDateTime;

@SpringBootApplication
@RestController
public class WebmvcApplication {

	public static void main(String[] args) {
		SpringApplication.run(WebmvcApplication.class, args);
	}

	@ResponseStatus(HttpStatus.ACCEPTED)
	@GetMapping("/status")
	public String status() {
		return "status";
	}

	@GetMapping("/")
	public String hello() {
		return "1. Hello from Spring MVC and Tomcat, " + LocalDateTime.now();
	}
}

现在编码已完成，来构建docker镜像吧，进入父工程的pom.xml所在目录，执行以下命令：

mvn clean -U -DskipTests spring-boot:build-image

构建成功后输出信息如下（篇幅所限仅截取最后一小段）,耗时4分25秒，期间笔记本风扇狂转：

...
[INFO] Successfully built image 'docker.io/library/webmvc:1.0-SNAPSHOT'
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for spring-native-tutorials 1.0-SNAPSHOT:
[INFO] 
[INFO] spring-native-tutorials ............................ SUCCESS [  1.786 s]
[INFO] webmvc ............................................. SUCCESS [04:19 min]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  04:25 min
[INFO] Finished at: 2021-05-22T16:36:44+08:00
[INFO] ------------------------------------------------------------------------
[WARNING] The requested profile "nexus" could not be activated because it does not exist.

执行docker images命令，如下图，可见镜像已经生成：

在这里插入图片描述

查看镜像构成，可见每个layer都不大，共计七十多M：

(base) zhaoqindeMBP:~ zhaoqin$ docker history webmvc:1.0-SNAPSHOT
IMAGE          CREATED        CREATED BY   SIZE      COMMENT
b8ff54813ae0   41 years ago                69B
<missing>      41 years ago                452kB
<missing>      41 years ago                2.51MB
<missing>      41 years ago                57.2MB
<missing>      41 years ago                1.4MB
<missing>      41 years ago                268B
<missing>      41 years ago                17.3MB

镜像构建成功，可以验证基本功能了；

验证

执行以下命令，创建一个临时容器（控制台结束后容器会被清理掉）：

docker run --rm -p 8080:8080 webmvc:1.0-SNAPSHOT

控制台输出如下，79毫秒启动完成，真是一眨间的功夫：

(base) zhaoqindeMBP:~ zhaoqin$ docker run --rm -p 8080:8080 webmvc:1.0-SNAPSHOT
2021-05-22 09:34:57.578  INFO 1 --- [           main] o.s.nativex.NativeListener               : This application is bootstrapped with code generated with Spring AOT

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v2.5.0-SNAPSHOT)

2021-05-22 09:34:57.586  INFO 1 --- [           main] c.b.webmvc.WebmvcApplication             : Starting WebmvcApplication using Java 1.8.0_292 on 3529ec458896 with PID 1 (/workspace/com.bolingcavalry.webmvc.WebmvcApplication started by cnb in /workspace)
2021-05-22 09:34:57.586  INFO 1 --- [           main] c.b.webmvc.WebmvcApplication             : No active profile set, falling back to default profiles: default
2021-05-22 09:34:57.661  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
May 22, 2021 9:34:57 AM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-nio-8080"]
May 22, 2021 9:34:57 AM org.apache.catalina.core.StandardService startInternal
INFO: Starting service [Tomcat]
May 22, 2021 9:34:57 AM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet engine: [Apache Tomcat/9.0.46]
May 22, 2021 9:34:57 AM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring embedded WebApplicationContext
2021-05-22 09:34:57.669  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 79 ms
May 22, 2021 9:34:57 AM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-nio-8080"]
2021-05-22 09:34:57.713  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2021-05-22 09:34:57.713  INFO 1 --- [           main] c.b.webmvc.WebmvcApplication             : Started WebmvcApplication in 0.178 seconds (JVM running for 0.19)
2021-05-22 09:34:57.713  INFO 1 --- [           main] o.s.b.a.ApplicationAvailabilityBean      : Application availability state LivenessState changed to CORRECT
2021-05-22 09:34:57.714  INFO 1 --- [           main] o.s.b.a.ApplicationAvailabilityBean      : Application availability state ReadinessState changed to ACCEPTING_TRAFFIC

浏览器访问本机8080端口，如下图，应用基本功能正常：

在这里插入图片描述

再看看资源使用情况，命令是docker stats，如下可见，内存仅用了30M：

CONTAINER ID   NAME               CPU %     MEM USAGE / LIMIT     MEM %     NET I/O           BLOCK I/O     PIDS
6ce6c66fb4de   jovial_hertz       0.11%     30.69MiB / 3.844GiB   0.78%     1.49kB / 158B     4.31MB / 0B   18

我曾经在hub.docker.com上放了一个传统springboot应用制作的镜像bolingcavalry/hellojib:0.0.1-SNAPSHOT，现在拿来和Spring Native镜像对比一下，启动信息如下，耗时2036毫秒：

(base) zhaoqindeMacBook-Pro:~ zhaoqin$ docker run --rm -P docker.io/bolingcavalry/hellojib:0.0.1-SNAPSHOT

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)

2021-05-22 11:13:28.121  INFO 1 --- [           main] c.b.hellojib.HellojibApplication         : Starting HellojibApplication on ffb32e5b68b9 with PID 1 (/app/classes started by root in /)
2021-05-22 11:13:28.128  INFO 1 --- [           main] c.b.hellojib.HellojibApplication         : No active profile set, falling back to default profiles: default
2021-05-22 11:13:30.000  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-05-22 11:13:30.054  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-05-22 11:13:30.054  INFO 1 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.21]
2021-05-22 11:13:30.241  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-05-22 11:13:30.241  INFO 1 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2036 ms
2021-05-22 11:13:30.715  INFO 1 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2021-05-22 11:13:31.103  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2021-05-22 11:13:31.110  INFO 1 --- [           main] c.b.hellojib.HellojibApplication         : Started HellojibApplication in 3.618 seconds (JVM running for 4.297)
2021-05-22 11:13:48.866  INFO 1 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-05-22 11:13:48.866  INFO 1 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2021-05-22 11:13:48.880  INFO 1 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 14 ms

再用docker stats对比内存，传统springboot应用的容器消耗了三百多兆内存：

CONTAINER ID   NAME               CPU %     MEM USAGE / LIMIT     MEM %     NET I/O           BLOCK I/O     PIDS
ffb32e5b68b9   eager_williamson   0.64%     356.3MiB / 3.844GiB   9.05%     3.46kB / 2.29kB   0B / 0B       31
6ce6c66fb4de   jovial_hertz       0.11%     30.69MiB / 3.844GiB   0.78%     1.49kB / 158B     4.31MB / 0B   18

综上所述，Spring Native带来的优势是很明显的，不过请注意：2021年03月11日官方宣布的Spring Native只是beta版本，请不要用于生产环境！！！

下载插件失败

在实际操作过程中，经常会遇到maven插件或者docker镜像下载失败的情况，除了多试几次，您还可以考虑将项目放到github上去，借助github action在云端完成镜像构建

不用开发，直接体验

我已将镜像上传到hub.docker.com，完整名称是bolingcavalry/webmvc:1.0-SNAPSHOT，如果您只想体验一下native image的效果可以直接下载该镜像使用；

我是欣宸，期待与您一同畅游Java世界…