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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<font color="blue">native image</font>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：https://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<font color="blue">dmikusa/graalvm-tiny</font>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(https://github.com/zq2599/blog_demos)：
| 名称 | 链接 | 备注 |
|---|---|---|
| 项目主页 | https://github.com/zq2599/blog_demos | 该项目在GitHub上的主页 |
| git仓库地址(https) | 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<font color="blue">spring-native-tutorials</font>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<font color="blue">spring-native-tutorials</font>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<font color="blue">dmikusa/graalvm-tiny</font>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<font colot="blue">webmvc</font>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<font color="blue">docker images</font>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<font color="blue">docker stats</font>，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<font color="blue">bolingcavalry/hellojib:0.0.1-SNAPSHOT</font>，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<font color="blue">docker stats</font>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<font color="blue">请注意</font>：2021年03月11日官方宣布的Spring Native只是beta版本，<font color="red">请不要用于生产环境！！！</font>
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，具体操作请参考《用GitHub Actions制作Docker镜像》
不用开发，直接体验
- 我已将镜像上传到hub.docker.com，完整名称是<font color="blue">bolingcavalry/webmvc:1.0-SNAPSHOT</font>，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；
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https://github.com/zq2599/blog_demos
