Docker Learning Notes

Introduction：

What is Docker?

docker

1> Different applications may have different application environments, for example, dependencies for websites developed by .Net and by PHP are not the same. If install their dependencies on one server, debugging will take a long time and dependencies might be conflict to each other. For example, IIS and Apache access port conflicts. At this point, you have to isolate the website developed by .Net and the website developed by PHP. Traditionally, we can create different virtual machines on the server and put different applications on different virtual machines, but the cost of virtual machines is relatively high. Docker can realize the function of virtual machine isolation application environment, and it costs less than virtual machine.

2> When you develop the software on Ubuntu, but the operation and maintenance management is on CentOS, the operation and maintenance of your software from the development environment to the production environment will encounter some Ubuntu to CentOS problems, such as: a special version of the database only supported on Ubuntu but not on CentOS, so that you have to solve such problems during the process of transfer between operations. But if you use docker, you can directly transfer the development environment to operation and deploy by docker directly and faster than regular deployment.

3> On the server load, if you use virtual machines instead of docker, free memory will not be used.

Life cycle of docker:（image, container, registry）

1.docker image

2.docker container

3.docker registry

Deploying a web application with docker

1.pull source code to host

Subversion: svn checkout svn://svn_address [host_volume]
Git:git clone [.git file]

2.Packaging .jar/.war file through Maven/ANT/Other

mvn package / ant makewar / etc.

3.Write a Dockerfile

FROM [imageName：tag]
MAINTAINER [author] [contact_e-mail]
ADD [.jar file] [volume_in_docker_container]
RUN bash -c 'touch /opt/xxx.jar'
#Change timezone
RUN echo "Asia/Shanghai" > /etc/timezone && dpkg-reconfigure -f noninteractive tzdata
#expose default port [8080_for_tomcat]
EXPOSE 8080
#execute .war/.jar file
CMD ["catalina.sh","run"]       --for xxx.war
CMD ["java","-jar","/opt/xxx.jar"]   --for xxx.jar

4.Docker build

5.Docker run

Other commands for docker

sudo docker ps -a : List all containers
sudo docker images : List all images sudo docker images|grep test|awk '{print $3 }'|xargs sudo docker rmi : remove all images that contain ‘test’

Installation

Before Installing docker, we have to install and configure necessary environments.

Configure Java environment

sudo mkdir /opt/java
sudo mv jdk-8u162-linux-x64.tar.gz /opt/java
cd /opt/java/
sudo tar -zxvf *
sudo rm *.tar.gz
export JAVA_HOME=/opt/java/jdk1.8.0_162
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

Configure Maven Environment

sudo mkdir /opt/maven
sudo mv apache-maven3.5.2.tar.gz /opt/maven
cd /opt/maven
sudo tar -zxvf *
sudo rm *.tar.gz
export M2_HOME=/opt/maven/apache-maven-3.5.2
export PATH=$PATH:$M2_HOME/bin
export CLASSPATH=$CLASSPATH:$M2_HOME/lib
java- version
mvn -v

Install and configure Docker

sudo apt-get update
sudo apt-get install docker.io
sudo curl -sSL https://get.daocloud.io/daotools/set_mirror.sh | sh -s http://ff626ecd.m.daocloud.io
sudo systemctl restart docker.service

Integration with Jenkins

Why choose Jenkins?

Jenkins is an extensible continuous integration engine, mainly used in build / test software projects continuously and automatically and monitoring some of the tasks that are executed on time. So it can ensure developers and related personnel save time and effort to improve development efficiency.

Install Jenkins

wget -q -O - https://pkg.jenkins.io/debian/jenkins-ci.org.key | sudo apt-key add -  
sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
sudo apt-get update  
sudo apt-get install jenkins

SSL Configuration

Differences between Http and Https

● The HyperText Transfer Protocol (HTTP) protocol is used to transmit information between the Web browser and the web server. The HTTP protocol sends content in plaintext, and does not provide any way of data encryption. If an attacker intercepts the transmission message between the Web browser and the web server, the information can be read directly. Therefore, HTTP protocol is not suitable for transmitting some sensitive information, such as credit card number, password and other payment information.

● In order to solve this defect of the HTTP protocol, it is necessary to use another protocol: Hypertext Transfer Protocol Secure (HTTPS). In order to secure data transmission, HTTPS adds SSL protocol on the basis of HTTP. SSL relies on certificates to verify the identity of the server and encrypts the communication between the browser and the server.

HTTPvsHTTPS

● The data transmitted by the HTTP protocol are not encrypted, that is, plaintext, so it is very unsafe to use the HTTP protocol to transmit privacy information. In order to ensure the encryption and transmission of these privacy data, the Netscape Co designed the SSL (Secure Sockets Layer) protocol to encrypt the data transmitted by the HTTP protocol—HTTPS. To put it simply, the HTTPS protocol is a network protocol constructed by SSL+HTTP protocol, which is capable of encrypting transmission and identity authentication,so it’s more secure than HTTP protocol.

Apply for a SSL certificate

● There are several ways to apply a SSL certificate, and I chose TrustAsia SSL certificate.The process of application will not be detailed. Below are the certificates for Apache, IIS, Nginx and Tomcat: SSL-certificate-1

Configure SSL for Spring Boot project

● Put the certificate( .jks file in tomcat folder) in the project at the application.yml level directory. SSL-certificate-2 ● Add configurations for ssl in applcation.yml( or application.properties) SSL-configurations

● Add http redirect in the Spring Boot application file

@Bean
public EmbeddedServletContainerFactory servletContainer(){
    TomcatEmbeddedServletContainerFactory tomcat=new TomcatEmbeddedServletContainerFactory(){
        @Override
        protected void postProcessContext(Context context) {
            SecurityConstraint securityConstraint=new SecurityConstraint();
            securityConstraint.setUserConstraint("CONFIDENTIAL");//confidential
            SecurityCollection collection=new SecurityCollection();
            collection.addPattern("/*");
            securityConstraint.addCollection(collection);
            context.addConstraint(securityConstraint);
        }
    };
    tomcat.addAdditionalTomcatConnectors(httpConnector());
    return tomcat;
}

@Bean
public Connector httpConnector() {
    Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
    connector.setScheme("http");
    // The port number of the HTTP that Connector monitors
    connector.setPort(80);
    connector.setSecure(false);
    // Redirect port after monitoring HTTP port
    connector.setRedirectPort(443);
    return connector;
}

Add ‘Post Steps’-‘Execute shell’ in Jenkins

cd /var/lib/jenkins/jobs/wxblog
sudo docker build -t wxblog:$BUILD_NUMBER .
sudo docker ps -a | grep wxblog | awk '{print $1}' | xargs sudo docker rm -f
sudo docker run -d -p 80:80 -p 443:443 --name wxblog_$BUILD_NUMBER wxblog:$BUILD_NUMBER
sudo docker images|grep wxblog|awk '{print $3 }'|xargs sudo docker rmi

● DON’T FORGET to run both ports: -p 80:80 -p 443:443.


● Congratulation! When you visit http://www.amazingxu.xyz , the website will redirect to https://www.amazingxu.xyz with a secure mark beside your address bar : )

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