Docker learning essay

1. Installation configuration:
    1. Installation (centos7):
          yum install docker -y
          yum install curl -y
    2. Configuration (centos7) is convenient for later development with spring-boot:         

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

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

　　   test whether it works

curl http://127.0.0.1:2375/info

2. Basic commands:

    1. Start|stop|restart:
        systemctl start|stop|restart docker
    2. Search for mirrors:
        docker search java  //Search for mirrors whose names contain java. The parts listed below show that the search matches NAME, DESCRIPTION
       INDEX NAME DESCRIPTION STARS OFFICIAL AUTOMATED docker.io
        docker.io/node Node.js is a JavaScript-based platform for... 5492 [OK]       
        docker.io docker.io/tomcat Apache Tomcat is an open source implementa... 1823 [OK]       
        docker. io docker.io/java Java is a concurrent, class-based, and obj... 1703 [OK]       
        docker.io   docker.io/openjdk                                      OpenJDK is an open-source implementation o...   938       [OK]       
        docker.io   docker.io/ghost                                        Ghost is a free and open source blogging p...   753       [OK]       
        docker.io   docker.io/anapsix/alpine-java                          Oracle Java 8 (and 7) with GLIBC 2.23 over...   303                  [OK]
        docker.io   docker.io/jetty                                        Jetty provides a Web server and javax.serv...   240       [OK]       
        docker.io   docker.io/couchdb                                      CouchDB is a database that uses JSON for d...   202       [OK]      
    3、docker pull java//下载镜像，将下载NAME为java的镜像，即上面第3行
    4. docker images //Display existing images
    5. docker rmi e856e4f0e190 //Delete an image, note that the last string is the IMAGE ID , you need to use docker images to list it to see it; there may be dependencies, you need to delete it first Dependent mirrors.
    6. docker build -t my-image . //Use Dockerfile to build an image. Note that the last dot indicates that the Dockerfile is in the current directory, and there are examples behind the Dockerfile. The principle is basically to create another image my-image according to an image.
    7. docker run --name my-app -p 80:8080 -d my-image //Run the image instance, my-app instance name, my-image image name.     8. docker
    stop|start|rm my-app //stop|start|delete an instance, pay attention to the deletion must stop first

2. Dockerfile:
    FROM java //Indicates that
    VOLUME is created based on the image java /tmp //Create a directory, because tomcat needs to use the temporary directory
    ADD app.jar app.jar //Add app.jar in the same directory of Dockerfile to the image The name is app.jar   
    ENV JAVA_OPTS="" //Set the environment variable
  ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar /app. jar" ]//Run the command after startup

    Of course, the configuration of Dockerfile is more than that. You can search for it yourself when you need it.

3. Combine spring-boot:
    1. pom.xml:
     <plugin>
                <groupId>com.spotify</groupId>
                <artifactId>docker-maven-plugin</artifactId>
                <version>1.0.0</version>
                <configuration >
                    <imageName>${docker.image.prefix}/${project.artifactId}</imageName>
                    <dockerDirectory>src/main/docker</dockerDirectory> <!-- specifies the directory of the Dockerfile-->
                    <dockerHost> http://192.168.1.168:2375</dockerHost> <!-- The target machine and port for running docker, note that the port is configured in the first step -->
                    <resources>
                        <resource>
                            <targetPath>/</targetPath>
                            <directory>${project.build.directory}</directory>
                            <include>${project.build.finalName}.jar</include>
                        </resource>
                    </resources>
                </configuration>
            </plugin>

    2、Dockerfile（src/main/docker目录下，上一步配置）：
        FROM java
                VOLUME /tmp
                ADD springboot.demo-0.0.1-SNAPSHOT.jar app.jar
                RUN bash -c 'touch /app.jar'
            ENV JAVA_OPTS=""
             ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar /app.jar" ]

    3. Build: mvn package docker:build
    4. Run on the target machine:
        docker run --name demo-app -p 80:8080 springboot/springboot.demo //demo-app is the instance name; springboot/springboot.demo is The image name built remotely using maven corresponds to the previous pom.xml configuration.