1. 介绍

介绍如何使用docker提供容器服务.

1.1. 安装docker

参看Docker 使用 - 提供外部扩展服务部分的安装docker

2. 使用

2.1. 使用gradle 插件

2.1.1. 添加插件

参看Docker 使用 - 提供外部扩展服务部分的安装docker 一样的方式安装gradle插件

2.1.2. 应用入口脚本

创建容器的入口运行脚本文件.

src/main/docker/app-entrypoint.sh

#!/bin/sh
java -Djava.security.egd=file:/dev/./urandom -jar /app/application.war

2.1.3. 构建image

配置如下几个Gradle task 任务: 构建可运行war包 , 复制资源至临时目录, 产生Dockerfile 文件并构建 docker image.

build.gradle

import com.bmuschko.gradle.docker.tasks.image.Dockerfile
import com.bmuschko.gradle.docker.tasks.image.DockerBuildImage
...
..
.
ext {
    dockerTag = "ea-sample/${project.name}:${project.version}".toLowerCase()   (1)
    dockerBuildDir = mkdir("${buildDir}/docker")    (2)
}
task prepareDocker(type: Copy, dependsOn: assemble) {    (3)
    description = 'Copy files from src/main/docker and application war to Docker temporal build directory'
    group = 'Docker'

    from 'src/main/docker'
    from project.war

    into dockerBuildDir
}
task createDockerfile(type: Dockerfile, dependsOn: prepareDocker) {   (4)
    description = 'Create a Dockerfile file'
    group = 'Docker'

    destFile = project.file("${dockerBuildDir}/Dockerfile")

    from 'openjdk:8u151-jdk-alpine'
    maintainer 'John Doe "john.doe@example.com"'

    exposePort 8080

    workingDir '/app'

    copyFile jar.archiveName, 'application.war'
    copyFile 'app-entrypoint.sh', 'app-entrypoint.sh'   (5)
    runCommand 'chmod +x app-entrypoint.sh'

    entryPoint '/app/app-entrypoint.sh'  (5)
}
task buildImage(type: DockerBuildImage, dependsOn: createDockerfile) { (6)
    description = 'Create Docker image to run the GB application'
    group = 'Docker'

    inputDir = file(dockerBuildDir)
    tag = dockerTag
}
1 定义docker image 的名称 像 gb-sample/myProject:0.1
2 构建Docker image的临时目录
3 复制工程的war包 从 src/main/docker 到临时目录
4 创建 Dockerfile 文件
5 复制 app-entrypoint.sh 脚本 并将其定义为容器的入口点
6 构建 Docker image

2.1.4. 运行部署

执行命令

./gradlew buildImage

输出如下:

...
...
:complete:war
:complete:bootRepackage
:complete:assemble   (1)
:complete:prepareDocker
:complete:createDockerfile
:complete:buildImage   (2)
Building image using context '/home/docker-container/complete/build/docker'.
Using tag 'gb-sample/complete:0.1' for image.
Step 1/8 : FROM openjdk:8u151-jdk-alpine
---> 3642e636096d
Step 2/8 : MAINTAINER John Doe "john.doe@example.com"
---> Using cache
---> 3e1c67b067e8
Step 3/8 : EXPOSE 8080
---> Using cache
---> 144aadd0580e
Step 4/8 : WORKDIR /app
---> Using cache
---> c9af01e696f8
Step 5/8 : COPY complete-0.1.war application.war
---> e4f41e8f0840
Removing intermediate container 6dccf4039811
Step 6/8 : COPY app-entrypoint.sh app-entrypoint.sh
---> 0be562313720
Removing intermediate container 595d0cb7b9d2
Step 7/8 : RUN chmod +x app-entrypoint.sh
---> Running in 3b41eb944045
---> 5f6fa6b0ab9a
Removing intermediate container 3b41eb944045
Step 8/8 : ENTRYPOINT /app/app-entrypoint.sh
---> Running in 3221a85ae904
---> 68f5588d1134
Removing intermediate container 3221a85ae904
Successfully built 68f5588d1134
Successfully tagged gb-sample/complete:0.1   (3)
Created image with ID '68f5588d1134'.

BUILD SUCCESSFUL

Total time: 11.453 secs
1 assemble 组装任务后,运行新的docker 任务
2 基于Dockerfile创建docker image
3 gb-sample/complete:0.1 docker image 文件创建成功

查看docker images

$ docker images
REPOSITORY                     TAG                 IMAGE ID            CREATED             SIZE
gb-sample/complete         0.1                 68f5588d1134        3 minutes ago       143MB

运行程序

运行如下程序:

$ docker run -p 8080:8080 gb-sample/complete:0.1

2.2. 使用Docker file

删除 Gradle tasks 任务: createDockerfile 和 buildImage.

删除 Gradle Docker Plugin 插件

删除 src/main/docker/app-entrypoint.sh. 我们在Dockerfile 文件中定义CMD目录.

创建文件Dockerfile

src/main/docker/Dockerfile

FROM openjdk:8u151-jdk-alpine
MAINTAINER John Doe "john.doe@example.com"

EXPOSE 8080

WORKDIR /app
COPY *.war application.war

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

Gradle task 任务 prepareDocker 使用处理.

创建image:

$ ./gradlew prepareDocker
$ docker build --tag="ea-sample/complete:0.1" build/docker/

手工创建Dockerfile的模式可以解耦对Docker Gradle 插件的依赖