用 Docker、Gradle 來構建、運行、發布一個 Spring Boot 應用

repositories {

mavenCentral()

}

dependencies {

classpath('org.springframework.boot:spring-boot-gradle-plugin:1.3.3.RELEASE')

// tag::build[]

classpath('se.transmode.gradle:gradle-docker:1.2')

// end::build[]

}

}

apply plugin: 'java'

apply plugin: 'eclipse'

apply plugin: 'idea'

apply plugin: 'spring-boot'

// tag::plugin[]

apply plugin: 'docker'

// end::plugin[]

// This is used as the docker image prefix (org)

group = 'gregturn'

jar {

baseName = 'docker-spring-boot-gradle'

version = '1.0.0'

}

// tag::task[]

task buildDocker(type: Docker, dependsOn: build) {

push = true

applicationName = jar.baseName

dockerfile = file('src/main/docker/Dockerfile')

doFirst {

copy {

from jar

into stageDir

}

}

}

// end::task[]

repositories {

mavenCentral()

}

sourceCompatibility = 1.8

targetCompatibility = 1.8

dependencies {

compile("org.springframework.boot:spring-boot-starter-web")

testCompile("org.springframework.boot:spring-boot-starter-test")

}

task wrapper(type: Wrapper) {

gradleVersion = '2.3'

}

Spring Boot gradle plugin 提供了很多方便的功能：

它收集的類路徑上所有 jar 文件，並構建成一個單一的、可運行的“über-jar”（德語，相關解釋可以移步至 http://stackoverflow.com/questions/11947037/what-is-an-uber-jar），這使得它更方便地執行和傳輸服務。

編寫 Spring Boot 應用

編寫一個簡單的 Spring Boot 應用 ：

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;

/**

* 主應用入口

* @author

* @date 2016年3月19日

*/

@SpringBootApplication

@RestController

public class Application {

@RequestMapping("/")

public String home() {

return "Hello Docker World."

+ "Welcome to ";

}

public static void main(String[] args) {

SpringApplication.run(Application.class, args);

}

}

解釋下上面的代碼：

• 類用 @SpringBootApplication @RestController 標識,可用 Spring MVC 來處理 Web 請求。
• @RequestMapping 將 / 映射到 home() ，並將”Hello Docker World” 文本作為響應。
• main() 方法使用 Spring Boot 的 SpringApplication.run() 方法來啟動應用。

運行程序

使用 Gradle

編譯：

1

gradle build

運行：

java -jar build/libs/docker-spring-boot-gradle-1.0.0.jar

訪問項目

如果程序正確運行，瀏覽器訪問 http://localhost:8080/，可以看到頁面 “Hello Docker World.” 字樣。

將項目容器化

Docker 使用 Dockerfile 文件格式來指定 image 層，

創建文件 src/main/docker/Dockerfile:

FROM frolvlad/alpine-oraclejdk8:slim

VOLUME /tmp

ADD docker-spring-boot-gradle-1.0.0.jar app.jar

ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

解釋下這個配置文件：

• VOLUME 指定了臨時文件目錄為/tmp。其效果是在主機 /var/lib/docker 目錄下創建了一個臨時文件，並鏈接到容器的/tmp。改步驟是可選的，如果涉及到文件系統的應用就很有必要了。/tmp目錄用來持久化到 Docker 數據文件夾，因為 Spring Boot 使用的內嵌 Tomcat 容器默認使用/tmp作為工作目錄
• 項目的 jar 文件作為 “app.jar” 添加到容器的
• ENTRYPOINT 執行項目 app.jar。為了縮短 Tomcat 啟動時間，添加一個系統屬性指向 “/dev/urandom” 作為 Entropy Source

構建 Docker Image

執行構建成為 docker image:

gradle build buildDocker

運行

運行 Docker Image

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

[root@waylau spring-boot]# docker run -p 8080:8080 -t waylau/docker-spring-boot-gradle

. ____ _ __ _ _

/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \

( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \

\\/ ___)| |_)| | | | | || (_| | ) ) ) )

' |____| .__|_| |_|_| |_\__, | / / / /

=========|_|==============|___/=/_/_/_/

:: 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 [

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> 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)

訪問項目

如果程序正確運行，瀏覽器訪問 http://localhost:8080/，可以看到頁面 “Hello Docker World.” 字樣。

推送 image 到 Docker Hub

首先，你在 Docker Hub 要有註冊賬號，且創建了相應的庫；

其次，docker 推送前，先要登錄，否則報unauthorized: access to the requested resource is not authorized的錯誤

執行：

docker login

輸出為：

[root@waylau spring-boot]# docker login

Username: waylau

Password:

Email: [email protected]

WARNING: login credentials saved in /root/.docker/config.json

Login Succeeded

執行推送

docker push waylau/docker-spring-boot-gradle

[root@waylau spring-boot]# docker push waylau/docker-spring-boot-gradle

The push refers to a repository [docker.io/waylau/docker-spring-boot-gradle]

751d29eef02e: Layer already exists

4da3741f39c7: Pushed

5f70bf18a086: Layer already exists

7e4d0cb13643: Layer already exists

8f045733649f: Layer already exists

latest: digest: sha256:eb4d5308ba1bb27489d808279e74784bda6761b3574f4298d746abba59b35164 size: 9415

鏡像加速器

Docker Hub 在國外，有時候拉取 Image 極其緩慢，可以使用國內的鏡像來實現加速

阿里雲

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 是您在阿里雲註冊後的專屬加速器地址：

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 是您在 DaoCloud 註冊後的專屬加速器地址：

源碼

獲取項目源碼， https://github.com/waylau/docker-demos 中的 samples/spring-boot-gradle

獲取項目鏡像， 執行

docker pull waylau/docker-spring-boot-gradle

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