简介

在文章《GraalVM和Spring Native尝鲜，一步步让Springboot启动飞起来，66ms完成启动》中，我们介绍了如何使用Spring Native和buildtools插件，打包出本地镜像，也打包成Docker镜像。本文探索一下，如果不通过这个插件来生成镜像。这样我们可以控制更多、了解更多。

创建Spring Boot项目

创建Spring Boot项目，引入Spring Native，我们主要使用的是Spring Native提供的AOT功能。如下：

<dependencies>
  <dependency>
    <groupId>org.springframework.experimental</groupId>
    <artifactId>spring-native</artifactId>
    <version>${spring-native.version}</version>
  </dependency>

  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
</dependencies>

<build>
  <plugins>
    <plugin>
      <groupId>org.springframework.experimental</groupId>
      <artifactId>spring-aot-maven-plugin</artifactId>
      <version>${spring-native.version}</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>
</build>

Build image的时候，我们需要引用依赖库，所以加上下面的插件：

<plugin>
  <artifactId>maven-dependency-plugin</artifactId>
  <executions>
    <execution>
      <phase>package</phase>
      <goals>
        <goal>copy-dependencies</goal>
      </goals>
      <configuration>
        <outputDirectory>${project.build.directory}/lib</outputDirectory>
      </configuration>
    </execution>
  </executions>
</plugin>

接着先编译出Java class，命令如下：

$ mvn clean package

打包本地镜像

前面的命令打包完，在target目录下会有一个lib目录，我们需要用上。通过native-image命令来生成镜像，如下：

$ native-image -cp ./target/classes/:target/lib/* com.pkslow.springboot.SpringbootGraalVMNativeMain Pkslow.SpringbootGraalVMNativeMain

这样就会生成一个可执行文件：Pkslow.SpringbootGraalVMNativeMain

执行如下：

$ ./Pkslow.SpringbootGraalVMNativeMain

使用了93ms来启动，还是很快的。

访问服务是正常的：

$ curl -i http://localhost:8080/hi-graalvm
HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Content-Length: 67
Date: Wed, 02 Nov 2022 15:08:44 GMT

This message is from Spring Boot built/run by GraalVM/Spring Native

创建Docker镜像

先拉取基础镜像：

$ docker pull springci/graalvm-ce:java11-0.12.x

进入容器看一下里面的状况：

$ docker run -it --rm --entrypoint bash springci/graalvm-ce:java11-0.12.x
root@d9b54bdce70a:/# pwd
/
root@d9b54bdce70a:/# java --version
openjdk 11.0.15 2022-04-19
OpenJDK Runtime Environment GraalVM 22.1.1.0-dev (build 11.0.15+10-jvmci-22.1-b06)
OpenJDK 64-Bit Server VM GraalVM 22.1.1.0-dev (build 11.0.15+10-jvmci-22.1-b06, mixed mode, sharing)
root@d9b54bdce70a:/# which java
/opt/java/bin/java
root@d9b54bdce70a:/# which native-image
/opt/java/bin/native-image

准备一下Dockerfile如下：

FROM springci/graalvm-ce:java11-0.12.x
VOLUME /tmp

ARG PORT=8080
ARG TIME_ZONE=Asia/Shanghai

ENV TZ=${TIME_ZONE}
EXPOSE ${PORT}
RUN pwd

RUN mkdir /pkslow-application
WORKDIR /pkslow-application/
RUN cd /pkslow-application
COPY target/classes/ /pkslow-application/classes/
COPY target/lib/ /pkslow-application/lib/

RUN native-image -cp /pkslow-application/classes/:/pkslow-application/lib/* \
    com.pkslow.springboot.SpringbootGraalVMNativeMain \
    Pkslow.SpringbootGraalVMNativeMain


ENTRYPOINT ["/pkslow-application/Pkslow.SpringbootGraalVMNativeMain"]

打包Docker镜像：

$ docker build . -t pkslow/spring-boot-native-without-buildtools:1.0-SNAPSHOT -f src/main/dker/Dockerfile

完成后通过下面命令启动，57ms完成启动：

$ docker run -it -p 8080:8080 --rm pkslow/spring-boot-native-without-buildtools:0-SNAPSHOT
2022-11-02 23:48:40.918  INFO 1 --- [           main] o.s.nativex.NativeListener               : AOT mode enabled

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.6.2)

2022-11-02 23:48:40.920  INFO 1 --- [           main] c.p.s.SpringbootGraalVMNativeMain        : Starting SpringbootGraalVMNativeMain using Java 11.0.15 on 12528bd45fd7 with PID 1 (/pkslow-application/Pkslow.SpringbootGraalVMNativeMain started by root in /pkslow-application)
2022-11-02 23:48:40.920  INFO 1 --- [           main] c.p.s.SpringbootGraalVMNativeMain        : No active profile set, falling back to default profiles: default
2022-11-02 23:48:40.934  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2022-11-02 23:48:40.935  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2022-11-02 23:48:40.935  INFO 1 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.56]
2022-11-02 23:48:40.940  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2022-11-02 23:48:40.940  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 19 ms
2022-11-02 23:48:40.963  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2022-11-02 23:48:40.964  INFO 1 --- [           main] c.p.s.SpringbootGraalVMNativeMain        : Started SpringbootGraalVMNativeMain in 0.057 seconds (JVM running for 0.061)
2022-11-02 23:48:57.098  INFO 1 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2022-11-02 23:48:57.098  INFO 1 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2022-11-02 23:48:57.098  INFO 1 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 0 ms

测试正常启动：

$ curl -i http://127.0.0.1:8080/hi-graalvm
HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Content-Length: 67
Date: Wed, 02 Nov 2022 15:49:05 GMT

This message is from Spring Boot built/run by GraalVM/Spring Native

为了集成打包镜像到CI/CD中，在pom添加以下插件：

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>exec-maven-plugin</artifactId>
  <version>3.0.0</version>
  <executions>
    <execution>
      <phase>install</phase>
      <goals>
        <goal>exec</goal>
      </goals>
      <configuration>
        <skip>${docker.skip}</skip>
        <executable>docker</executable>
        <arguments>
          <argument>build</argument>
          <argument>.</argument>
          <argument>-t</argument>
          <argument>pkslow/${project.artifactId}:${project.version}</argument>
          <argument>-f</argument>
          <argument>src/main/docker/Dockerfile</argument>
        </arguments>
      </configuration>
    </execution>
  </executions>
</plugin>