前言

搭建一個簡單的Spring Boot項目與Docker技術(shù)進(jìn)行整合,使用Maven來構(gòu)建Docker鏡像并推送至本地Docker Registry,最后對項目進(jìn)行部署時只需根據(jù)鏡像啟動相應(yīng)的容器即可.

環(huán)境搭建

• JDK1.8
• Spring Boot 1.5.7
• Maven 3.3.9
• Docker

1.使用IDEA新建一個Spring Boot項目,在pom.xml中添加如下配置:

<?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>

    <groupId>hello</groupId>
    <artifactId>hello-api</artifactId>
    <version>1.0.0</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.7.RELEASE</version>
        <relativePath/>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.13</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>hello</finalName>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

我們使用了spring-boot-maven-plugin插件來打包生成一個可直接運(yùn)行的hello.jar包.
2.新建一個HelloApplication類.

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class HelloApplication {
    public static void main(String[] args) {
        SpringApplication.run(HelloApplication.class, args);
    }
}

3.新建一個控制類HelloController,用于接收Http請求.

package hello.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    @RequestMapping(value = "/hi", method = RequestMethod.GET)
    public String hello() {
        return "hi";
    }
}

4.然后使用mvn package命令開始對spring boot項目進(jìn)行打包構(gòu)建,生成對應(yīng)的target目錄.

image

cd到此目錄下執(zhí)行java -jar hello.jar啟動項目,開啟瀏覽器訪問http://localhost:8080/hi,頁面返回:hi說明spring boot項目配置運(yùn)行正常.
5.開始為項目添加Docker支持.
Maven規(guī)范要求所有的資源文件都應(yīng)放在src/main/resources目錄下,我們在應(yīng)用的resources目錄下創(chuàng)建一個空白的文件Dockerfile,用來說明如何構(gòu)建docker 鏡像,打開Dockerfile文件編寫以下指令:

FROM java:8
MAINTAINER "william"<952408421@qq.com>
ADD hello.jar app.jar
EXPOSE 8080
CMD java -jar app.jar

以上指令使用了Jdk8環(huán)境為基礎(chǔ)鏡像,通過ADD指令將生成的hello.jar包復(fù)制到docker容器中,并重命名為app.jar,應(yīng)用將開啟8080端口,最后使用java -jar指令執(zhí)行jar包.
6.使用Maven來構(gòu)建Docker鏡像.
接下來我們要使用maven讀取Dockerfile文件來構(gòu)建鏡像并推送到注冊中心去,由于Docker默認(rèn)的鏡像注冊中心為Docke Hub(地址是docker.io),當(dāng)使用docker push命令推送鏡像時,實際上都是推送到了docker.io的地址上的,如果需要推送到本地自己搭建的鏡像注冊中心,則鏡像名稱需要添加前綴ip:port,因為我們之前已經(jīng)搭好了本地Registry了,所以在pom.xml文件中添加properties:

    <properties>
        <docker.registry>192.168.56.101:5000</docker.registry>
    </properties>

然后再添加maven plugin到pom.xml文件中:

            <plugin>
                <groupId>com.spotify</groupId>
                <artifactId>docker-maven-plugin</artifactId>
                <version>0.4.10</version>
                <configuration>
                    <imageName>${docker.registry}/${project.groupId}/${project.artifactId}:${project.version}</imageName>
                    <dockerDirectory>${project.build.outputDirectory}</dockerDirectory>
                    <resources>
                        <resource>
                            <directory>${project.build.directory}</directory>
                            <include>${project.build.finalName}.jar</include>
                        </resource>
                    </resources>
                </configuration>
            </plugin>

簡要說明一下configuration的配置:

• imageName:用于指定鏡像的完整名稱,其中{docker.registry}為注冊中心地址,{project.groupId}為倉庫名稱,{project.artifactId}為鏡像名稱,${project.version}為鏡像標(biāo)簽名.
• dockerDirectory:用于指定Dockerfile文件所在的目錄.
• resources.resource.directory:用于指定需要復(fù)制的根目錄,${project.build.directory}表示target目錄.
• resources.resource.include:用于指定需要復(fù)制的文件,${project.build.finalName}.jar表示生成的jar包.

7.使用docker build命令來構(gòu)建鏡像.

 mvn docker:build

執(zhí)行后發(fā)現(xiàn)構(gòu)建鏡像不成功,報異常localhost:2375 Connection refused :

[INFO] Building image 192.168.56.101:5000/hello/hello-api:1.0.0
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 13.102 s
[INFO] Finished at: 2018-07-30T15:56:40+08:00
[INFO] Final Memory: 26M/218M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:0.4.10:build (default-cli) on project hello-api: Exception caught: java.util.concurrent.ExecutionException: com.spotify.docker.client.shaded.javax.ws.rs.ProcessingException: org.apache.http.conn.HttpHostConnectException: Connect to localhost:2375 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1] failed: Connection refused: connect -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

網(wǎng)上搜索了很久找到了一種解決Connect to localhost:2375的問題的方法:在pom.xml文件的configuration中添加一行dockerHost.

                <configuration>
                    <imageName>${docker.registry}/${project.groupId}/${project.artifactId}:${project.version}</imageName>
                    <dockerDirectory>${project.build.outputDirectory}</dockerDirectory>
                    <dockerHost>http://192.168.56.101:2375</dockerHost>
                    ......
                </configuration>

我們再來執(zhí)行mvn docker:build試試,這一次同樣是報Connection refused的錯,錯誤信息由localhost變成了192.168.56.101:

[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10.086 s
[INFO] Finished at: 2018-07-30T16:13:36+08:00
[INFO] Final Memory: 27M/302M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:0.4.10:build (default-cli) on project hello-api: Exception caught: java.util.concurrent.ExecutionException: com.spotify.docker.client.shaded.javax.ws.rs.ProcessingException: org.apache.http.conn.HttpHostConnectException: Connect to 192.168.56.101:2375 [/192.168.56.101] failed: Connection refused: connect -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

繼續(xù)網(wǎng)上搜索,發(fā)現(xiàn)在默認(rèn)情況下Docker守護(hù)進(jìn)程Unix socket(/var/run/docker.sock)來進(jìn)行本地進(jìn)程通信,而不會監(jiān)聽任何端口,因此只能在本地使用docker客戶端或者使用Docker API進(jìn)行操作.如果想在其他主機(jī)上操作Docker主機(jī),就需要讓Docker守護(hù)進(jìn)程打開一個HTTP Socket,這樣才能實現(xiàn)遠(yuǎn)程通信.我們是在windows上打包構(gòu)建的,所以需要讓centos7上的docker服務(wù)開啟遠(yuǎn)程訪問.
8.開啟docker遠(yuǎn)程服務(wù),執(zhí)行vi命令:

vi /usr/lib/systemd/system/docker.service

在[Service]部分的最下面添加下面兩行:

ExecStart=
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock

然后讓docker重新讀取配置文件,并重啟docker服務(wù).

systemctl daemon-reload
systemctl restart docker

查看docker進(jìn)程,發(fā)現(xiàn)docker守護(hù)進(jìn)程在已經(jīng)監(jiān)聽2375的tcp端口了.

[root@bogon ~]# ps -ef|grep docker
root      1956     1  3 16:32 ?        00:00:00 /usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock
root      1959  1956  0 16:32 ?        00:00:00 docker-containerd -l unix:///var/run/docker/libcontainerd/docker-containerd.sock --metrics-interval=0 --start-timeout 2m --state-dir /var/run/docker/libcontainerd/containerd --shim docker-containerd-shim --runtime docker-runc
root      2056  1956  0 16:32 ?        00:00:00 /usr/bin/docker-proxy -proto tcp -host-ip 0.0.0.0 -host-port 5000 -container-ip 172.17.0.2 -container-port 5000
root      2062  1959  0 16:32 ?        00:00:00 docker-containerd-shim ffac4cc26314b42610071b521cbd9c39e00618f4277ca967c1fee31193ff4041 /var/run/docker/libcontainerd/ffac4cc26314b42610071b521cbd9c39e00618f4277ca967c1fee31193ff4041 docker-runc
root      2075  2062  2 16:32 ?        00:00:00 registry serve /etc/docker/registry/config.yml
root      2103  1259  0 16:32 pts/0    00:00:00 grep --color=auto docker

最后我們再來執(zhí)行mvn docker:build命令:

[INFO] Building image 192.168.56.101:5000/hello/hello-api:1.0.0
Step 1/5 : FROM java:8
 ---> d23bdf5b1b1b
Step 2/5 : MAINTAINER "zhangzhongwu"<952408421@qq.com>
 ---> Running in 3b331db3b81b
 ---> bae408e908a0
Removing intermediate container 3b331db3b81b
Step 3/5 : ADD hello.jar app.jar
 ---> 3cc7f118a38c
Removing intermediate container 9a3bf9971e98
Step 4/5 : EXPOSE 8080
 ---> Running in 7b5c1dccbd4e
 ---> 5a0c6401e95a
Removing intermediate container 7b5c1dccbd4e
Step 5/5 : CMD java -jar app.jar
 ---> Running in 3ba012d83276
 ---> 68bbcea2575f
Removing intermediate container 3ba012d83276
Successfully built 68bbcea2575f
Successfully tagged 192.168.56.101:5000/hello/hello-api:1.0.0
[INFO] Built 192.168.56.101:5000/hello/hello-api:1.0.0
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 23.931 s
[INFO] Finished at: 2018-07-30T16:33:49+08:00
[INFO] Final Memory: 28M/272M
[INFO] ------------------------------------------------------------------------

好了,我們可以看到鏡像已經(jīng)構(gòu)建成功了.
9.接下來就是把已經(jīng)構(gòu)建好的鏡像推送到Docker Registry了.
我們執(zhí)行mvn docker:build docker:push命令
然后打開linux終端,輸入命令docker images查看所有的鏡像:

[root@bogon ~]# docker images
REPOSITORY                            TAG                 IMAGE ID            CREATED             SIZE
192.168.56.101:5000/hello/hello-api   1.0.0               68bbcea2575f        2 minutes ago       673MB
nginx                                 latest              c82521676580        5 days ago          109MB
registry                              latest              b2b03e9146e1        3 weeks ago         33.3MB
java                                  8                   d23bdf5b1b1b        18 months ago       643MB
[root@bogon ~]# 

可以看到"192.168.56.101:5000/hello/hello-api"這個鏡像,說明我們已經(jīng)把鏡像成功推送到注冊中心了.
10.最后一步就是運(yùn)行該鏡像,啟動容器并將容器的8080端口綁定到宿主機(jī)的58080端口上:

[root@bogon ~]# docker run -d -p 58080:8080 192.168.56.101:5000/hello/hello-api:1.0.0
9d9363d1213df621c3f610b3466d265332ef42600461ae3e50ff25418b751b65
[root@bogon ~]# 

執(zhí)行以下命令驗證服務(wù)是否啟動成功:

[root@bogon /]# curl -XGET http://192.168.56.101:58080//hello/hi
hi[root@bogon /]# 

返回字符串"hi",說明已經(jīng)成功使用Docker部署Spring Boot項目了.