用 Docker 构建、运行、发布来一个 Spring Boot 应用

朱雀 2022-07-29 10:33 180阅读 0赞

原文同步至 [http://waylau.com/docker-spring-boot/][http_waylau.com_docker-spring-boot]

--------------------

本文演示了如何用 Docker 构建、运行、发布来一个 Spring Boot 应用。

## Docker 简介 ##

[Docker][] 是一个 Linux 容器管理工具包，具备“社交”方面，允许用户发布容器的 image (镜像)，并使用别人发布的 image。Docker image 是用于运行容器化进程的方案，在本文中，我们将构建一个简单的 Spring Boot 应用程序。

有关 Docker 的详细介绍，可以移步至 [《简述 Docker》][Docker 1]

## 前置条件 ##

*  [JDK 1.8+][JDK 1.8]
 *  [Maven 3.0+][Maven 3.0]
 *  Docker 最新版。有关 Docker 在的安装，可以参阅 [《Docker 在 CentOS 下的安装、使用》][Docker _ CentOS]。  
    如果你的电脑不是 Linux 系统，最好装个虚拟机，在虚拟机里面装个 Linux ，因为 Docker 的依赖 Linux。

## 用 Maven 构建项目 ##

### 创建目录结构 ###

项目的目录结构因符合 Maven 的约定。

在 \*nix 系统下执行 `mkdir -p src/main/java/docker_spring_boot` ,生产如下结构 :

└── src
        └── main
            └── java
                └── com
                    └── waylau
                        └── docker_spring_boot

### 创建 pom.xml 文件 ###

<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/maven-v4_0_0.xsd">
    
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.waylau</groupId>
        <artifactId>docker-spring-boot</artifactId>
        <packaging>jar</packaging>
        <version>1.0.0</version>
        <name>docker-spring-boot</name>
        <description>Getting started with Spring Boot and Docker</description>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.3.3.RELEASE</version>
            <relativePath/>
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
        
                <plugin>
                    <groupId>com.spotify</groupId>
                    <artifactId>docker-maven-plugin</artifactId>
                    <version>0.4.3</version>
                    <configuration>
                        <imageName>${docker.image.prefix}/${project.artifactId}</imageName>
                        <dockerDirectory>src/main/docker</dockerDirectory>
                        <resources>
                            <resource>
                                <targetPath>/</targetPath>
                                <directory>${project.build.directory}</directory>
                                <include>${project.build.finalName}.jar</include>
                            </resource>
                        </resources>
                    </configuration>
                </plugin>
        
            </plugins>
        </build>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <docker.image.prefix>waylau</docker.image.prefix>
            <spring.boot.version>1.3.3.RELEASE</spring.boot.version>
        </properties>
    </project>

[Spring Boot Maven plugin][] 提供了很多方便的功能：

*  它收集的类路径上所有 jar 文件，并构建成一个单一的、可运行的“über-jar”，这使得它更方便地执行和传输服务。
 *  它搜索的 `public static void main()` 方法来标记为可运行的类。
 *  它提供了一个内置的依赖解析器，用于设置版本号以匹配 [Spring Boot 的依赖][Spring Boot]。您可以覆盖任何你想要的版本，但它会默认选择的 Boot 的版本集。

Spotify 的 [docker-maven-plugin][] 插件是用于构建 Maven 的 Docker Image

*  `imageName`指定了镜像的名字，本例为 `waylau/docker-spring-boot`
 *  `dockerDirectory`指定 Dockerfile 的位置
 *  `resources`是指那些需要和 Dockerfile 放在一起，在构建镜像时使用的文件，一般应用 jar 包需要纳入。本例，只需一个 jar 文件。

## 编写 Spring Boot 应用 ##

编写一个简单的 Spring Boot 应用 ：

`src/main/java/com/waylau/docker_spring_boot/Application.java`:

package com.waylau.docker_spring_boot;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    /** * 主应用入口 * @author <a href="http://waylau.com">waylau.com</a> * @date 2016年3月19日 */
    @SpringBootApplication
    @RestController
    public class Application { 
    
        @RequestMapping("/")
        public String home() {
            return "Hello Docker World."
                    + "<br />Welcome to <a href='http://waylau.com'>waylau.com</a></li>";
        }
    
        public static void main(String[] args) {
            SpringApplication.run(Application.class, args);
        }
    
    }

解释下上面的代码：

*  类用 `@SpringBootApplication` `@RestController` 标识,可用 Spring MVC 来处理 Web 请求。
 *  `@RequestMapping` 将 `/` 映射到 `home()` ，并将”Hello Docker World” 文本作为响应。
 *  `main()` 方法使用 Spring Boot 的 `SpringApplication.run()` 方法来启动应用。

## 运行程序 ##

### 使用 Maven ###

编译：

> mvn package

运行：

> java -jar target/docker-spring-boot-1.0.0.jar

### 访问项目 ###

如果程序正确运行，浏览器访问 [http://localhost:8080/][http_localhost_8080]，可以看到页面 “Hello Docker World.” 字样。

## 将项目容器化 ##

Docker 使用 [Dockerfile][] 文件格式来指定 image 层，

创建文件 `src/main/docker/Dockerfile`:

FROM frolvlad/alpine-oraclejdk8:slim
    VOLUME /tmp
    ADD docker-spring-boot-1.0.0.jar app.jar
    ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

解释下这个配置文件：

*  `VOLUME` 指定了临时文件目录为`/tmp`。其效果是在主机 `/var/lib/docker` 目录下创建了一个临时文件，并链接到容器的`/tmp`。改步骤是可选的，如果涉及到文件系统的应用就很有必要了。`/tmp`目录用来持久化到 Docker 数据文件夹，因为 Spring Boot 使用的内嵌 Tomcat 容器默认使用`/tmp`作为工作目录
 *  项目的 jar 文件作为 “app.jar” 添加到容器的
 *  `ENTRYPOINT` 执行项目 app.jar。为了缩短 [Tomcat 启动时间][Tomcat]，添加一个系统属性指向 “/dev/urandom” 作为 Entropy Source

## 构建 Docker Image ##

执行构建成为 docker image:

> mvn package docker:build

## 运行 ##

运行 Docker Image

> docker run -p 8080:8080 -t waylau/docker-spring-boot

[root@waylau spring-boot]# docker run -p 8080:8080 -t waylau/docker-spring-boot
    
      .   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Boot ::        (v1.3.3.RELEASE)
    
    2016-03-20 08:45:51.276  INFO 1 --- [           main] c.waylau.docker_spring_boot.Application  : Starting Application v1.0.0 on 048fb623038f with PID 1 (/app.jar started by root in /)
    2016-03-20 08:45:51.289  INFO 1 --- [           main] c.waylau.docker_spring_boot.Application  : No active profile set, falling back to default profiles: default
    2016-03-20 08:45:51.722  INFO 1 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@669af5fc: startup date [Sun Mar 20 08:45:51 GMT 2016]; root of context hierarchy
    2016-03-20 08:45:54.874  INFO 1 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Overriding bean definition for bean 'beanNameViewResolver' with a different definition: replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
    2016-03-20 08:45:57.893  INFO 1 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
    2016-03-20 08:45:57.982  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
    2016-03-20 08:45:57.984  INFO 1 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.0.32
    2016-03-20 08:45:58.473  INFO 1 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2016-03-20 08:45:58.473  INFO 1 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 6877 ms
    2016-03-20 08:45:59.672  INFO 1 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean        : Mapping servlet: 'dispatcherServlet' to [/]
    2016-03-20 08:45:59.695  INFO 1 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'characterEncodingFilter' to: [/*]
    2016-03-20 08:45:59.701  INFO 1 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
    2016-03-20 08:45:59.703  INFO 1 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'httpPutFormContentFilter' to: [/*]
    2016-03-20 08:45:59.703  INFO 1 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'requestContextFilter' to: [/*]
    2016-03-20 08:46:00.862  INFO 1 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@669af5fc: startup date [Sun Mar 20 08:45:51 GMT 2016]; root of context hierarchy
    2016-03-20 08:46:01.166  INFO 1 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String com.waylau.docker_spring_boot.Application.home()
    2016-03-20 08:46:01.189  INFO 1 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
    2016-03-20 08:46:01.190  INFO 1 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
    2016-03-20 08:46:01.302  INFO 1 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2016-03-20 08:46:01.302  INFO 1 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2016-03-20 08:46:01.438  INFO 1 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2016-03-20 08:46:01.833  INFO 1 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
    2016-03-20 08:46:02.332  INFO 1 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
    2016-03-20 08:46:02.343  INFO 1 --- [           main] c.waylau.docker_spring_boot.Application  : Started Application in 13.194 seconds (JVM running for 15.828)

## 推送 image 到 Docker Hub ##

首先，你在 Docker Hub 要有注册账号，且创建了相应的库；

其次，docker 推送前，先要登录，否则报`unauthorized: access to the requested resource is not authorized`的错误

执行：

> docker login

[root@waylau spring-boot]# docker login
    Username: waylau
    Password: 
    Email: waylau521@gmail.com
    WARNING: login credentials saved in /root/.docker/config.json
    Login Succeeded

执行推送

> docker push waylau/docker-spring-boot

[root@waylau spring-boot]# docker push waylau/docker-spring-boot
    The push refers to a repository [docker.io/waylau/docker-spring-boot]
    751d29eef02e: Layer already exists 
    4da3741f39c7: Pushed 
    5f70bf18a086: Layer already exists 
    7e4d0cb13643: Layer already exists 
    8f045733649f: Layer already exists 
    latest: digest: sha256:eb4d5308ba1bb27489d808279e74784bda6761b3574f4298d746abba59b35164 size: 9415

## 镜像加速器 ##

Docker Hub 在国外，有时候拉取 Image 极其缓慢，可以使用国内的镜像来实现加速

### 阿里云 ###

echo "DOCKER_OPTS=\"--registry-mirror=https://yourlocation.mirror.aliyuncs.com\"" | sudo tee -a /etc/default/docker
    sudo service docker restart

其中 [https://yourlocation.mirror.aliyuncs.com][https_yourlocation.mirror.aliyuncs.com] 是您在阿里云注册后的专属加速器地址：

### DaoCloud ###

sudo echo “DOCKER_OPTS=\”\$DOCKER_OPTS –registry-mirror=http://your-id.m.daocloud.io -d\”” >> /etc/default/docker
    sudo service docker restart

其中 [http://your-id.m.daocloud.io][http_your-id.m.daocloud.io] 是您在 DaoCloud 注册后的专属加速器地址：

## 源码 ##

获取项目源码，  
执行

> git clone [https://github.com/waylau/docker-demos.git][https_github.com_waylau_docker-demos.git]  
> cd docker-demos/samples/spring-boot

获取项目镜像，  
执行

> docker pull waylau/docker-spring-boot

## 参考引用 ##

*  [http://spring.io/guides/gs/spring-boot-docker/][http_spring.io_guides_gs_spring-boot-docker]
 *  [https://yq.aliyun.com/articles/2930?utm\_source=tuicool&utm\_medium=referral][https_yq.aliyun.com_articles_2930_utm_source_tuicool_utm_medium_referral]  
    \*\*

[http_waylau.com_docker-spring-boot]: http://waylau.com/docker-spring-boot/
[Docker]: https://docker.com/
[Docker 1]: http://waylau.com/ahout-docker/
[JDK 1.8]: http://www.oracle.com/technetwork/java/javase/downloads/index.html
[Maven 3.0]: http://maven.apache.org/download.cgi
[Docker _ CentOS]: http://waylau.com/docker-installation-centos/
[Spring Boot Maven plugin]: https://github.com/spring-projects/spring-boot/tree/master/spring-boot-tools/spring-boot-maven-plugin
[Spring Boot]: https://github.com/spring-projects/spring-boot/blob/master/spring-boot-dependencies/pom.xml
[docker-maven-plugin]: https://github.com/spotify/docker-maven-plugin
[http_localhost_8080]: http://localhost:8080/
[Dockerfile]: https://docs.docker.com/reference/builder/
[Tomcat]: http://wiki.apache.org/tomcat/HowTo/FasterStartUp#Entropy_Source
[https_yourlocation.mirror.aliyuncs.com]: https://yourlocation.mirror.aliyuncs.com
[http_your-id.m.daocloud.io]: http://your-id.m.daocloud.io
[https_github.com_waylau_docker-demos.git]: https://github.com/waylau/docker-demos.git
[http_spring.io_guides_gs_spring-boot-docker]: http://spring.io/guides/gs/spring-boot-docker/
[https_yq.aliyun.com_articles_2930_utm_source_tuicool_utm_medium_referral]: https://yq.aliyun.com/articles/2930?utm_source=tuicool&utm_medium=referral