Spring Boot and Docker deployment practices

First, you need to enable docker remote access function so that remote operations can be performed.

CentOS 6

Modify the /etc/default/docker file, and take effect after restart (service docker restart).

 DOCKER_OPTS="-H=unix:///var/run/docker.sock -H=0.0.0.0:2375"

CentOS 7

Open the /usr/lib/systemd/system/docker.service file and modify the ExecStart line.

Copy the code as follows: ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock

Take effect after restart

 systemctl daemon-reload systemctl restart docker.service

Whether the test takes effect

 curl http://127.0.0.1:2375/info

New Maven project

The pom.xml configuration is as follows:

 <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>test.springboot.docker</groupId> <artifactId>docker-springboot</artifactId> <version>0.0.1-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.3.RELEASE</version> </parent> <properties> <java.version>1.8</java.version> </properties> <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> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> <plugin> <groupId>com.spotify</groupId> <artifactId>docker-maven-plugin</artifactId> <version>0.4.14</version> <configuration> <imageName>${docker.image.prefix}/${project.artifactId}</imageName> <dockerDirectory>src/main/docker</dockerDirectory> <dockerHost>http://192.168.1.200:2375</dockerHost> <resources> <resource> <targetPath>/</targetPath> <directory>${project.build.directory}</directory> <include>${project.build.finalName}.jar</include> </resource> </resources> </configuration> </plugin> </plugins> </build></project>

1. imageName： Specifies the image's name
2. dockerDirectory： Specify the location of the Dockerfile
3. dockerHost： Specify Docker remote API address
4. resources： refers to files that need to be put together with Dockerfile and used when building images. Generally, application jar packages need to be included

Create Java classes

 package hello;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;@SpringBootApplication@RestControllerpublic class Application { @RequestMapping("/") public String home() { return "Hello Docker World"; } public static void main(String[] args) { SpringApplication.run(Application.class, args); }}

Create a Dockerfile

Create a file named Dockerfile in the src/main/docker directory, and the configuration is as follows:

 FROM javaVOLUME /tmpADD docker-springboot-0.0.1-SNAPSHOT.jar app.jarRUN bash -c 'touch /app.jar'ENV JAVA_OPTS=""ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar /app.jar" ]

FROM java: refers to the java image provided by the official Docker Hub. With this basic image, the Dockerfile can directly obtain its status through the FROM instruction - that is, java is already installed in the container, and then run the Spring Boot application through custom commands.

VOLUME /tmp: Create /tmp directory and persist to Docker data folder, because the embedded Tomcat container used by Spring Boot uses /tmp as the working directory by default.

ADD docker-springboot-0.0.1-SNAPSHOT.jar app.jar: Copy the application jar package to /app.jar

ENTRYPOINT: Indicates the command executed by default after the container is run

The complete directory structure is as follows:

Run the following command to create a Docker image:

 package docker:build

Docker startup image

Check whether the project is uploaded successfully

Start the image copy code as follows: docker run -p 8888:8080 springboot/docker-springboot

Access through a browser

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