How to build Jenkins+Maven+Git continuous integration environment on CentOS7

This article takes the deployment of Spring boot + Maven project as an example, uses Code Cloud as the code hosting repository, and builds a Jenkins continuous integration environment on CentOS 7.

1. Preparation

1.1 Install Java Environment

Jenkins is a continuous integration tool developed based on Java and needs to run in a Java environment. Use the following command to check whether Java is installed on your system:

yum list installed | grep jdk

If not, use the yum search command to find the openjdk version and select the appropriate jdk to install:

yum search openjdk 
yum -y install java-1.8.0-openjdk-devel

Verify that Java is installed successfully:

java -version

1.2 Install Maven

Run the following two commands in sequence:

wget http://repos.fedorapeople.org... -O /etc/yum.repos.d/epel-apache-maven.repo 
yum -y install apache-maven

Verify that Maven is installed successfully:

mvn -v

1.3 Install Git

Install directly through yum. After the installation is complete, check the version to verify whether the installation is successful:

yum -y install git 
git --version

2. Install and configure Jenkins:

2.1 Install Jenkins

Run the following three commands in sequence:

sudo wget https://pkg.jenkins.io/redhat... -O /etc/yum.repos.d/jenkins.repo 
sudo rpm --import https://pkg.jenkins.io/redhat... 
yum -y install jenkins

If a key has been imported from Jenkins before, rpm --import will fail because there is already a key. Ignore it and continue with the install.

2.2 Start Jenkins

Start Jenkins and set it to start automatically at boot:

systemctl start jenkins.service 
chkconfig jenkins on

Jenkins uses port 8080 by default. You can see the Jenkins web interface by visiting the following link:

http://<Server Address>:8080

If you cannot access it, check the firewall to see if there are any open ports, or use the command netstat -ntulp to check if the port is occupied.

2.3 Enter Jenkins

The first time you enter Jenkins, you need to enter the administrator password. Use the following command to view the initial password:

cat /var/lib/jenkins/secrets/initialAdminPassword

Select the default install suggested plugins to install the plugin. After the installation is complete, follow the steps to create a user. After the creation is complete, you can log in.

2.4 Configure Jenkins

Go to Manage Jenkins -> Global Tool Configuration and configure the JDK, Git and Maven paths in turn.

2.4.1 Check the JDK path

The software installed using yum will not help us configure environment variables. You cannot see the path by directly using the command echo $JAVA_HOME.

First, use the following command to check the path:

which java

The result you see is /usr/bin/java, but in fact this is just a soft link, not the actual directory where JDK is located.

Continue to use the following command to view:

ls -l /usr/bin/java

We see that /usr/bin/java points to /etc/alternatives/java. Unfortunately, this is not the actual path we are looking for.

Continue tracking:

ls -l /etc/alternatives/java

The result points to /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre/bin/java . The directory names of different versions of JDK may be slightly different. This is where the JDK is actually located.

Similarly, you can get the path where Maven is located.

2.4.2 Installing and configuring plugins

Go to Manage Jenkins -> Manage Plugins , search for and install Publish Over SSH and Maven Integration plugins. The Git Plugins plugin is already installed by default, so we don’t need to install it again.

Configure SSH password-free login

Before configuring the plugin, we generate a key pair on the Jenkins server. Run the following command to switch to the jenkins user:

sudo su jenkins

If you cannot switch, open the /etc/passwd file, find the line for jenkins, and change /bin/fasle to /bin/bash.

After the switch is successful, the user name of the command prompt may be bash-4.2$. If you want to display the user name normally, switch back to the root user and do the following:

Edit the file vi ~/.bash_profile
Add the statement export PS1='[u@h W]$'
Take effect immediately source ~/.bash_profile

Then switch to the jenkins user and it will display normally. Next, run the following command to generate a key pair:

ssh-keygen -t rsa

Press Enter all the way to complete, and two files, id_rsa and id_rsa.pub, will be generated in the /var/lib/jenkins/.ssh/ directory.

Append the contents of the id_rsa.pub file to the end of the /root/.ssh/authorized_keys file on the application server, one key per line. Note that it is the application server. Restart the ssh service on the application server:

systemctl restart sshd.service

Now Jenkins can log in to the application server without a password. Test it by running the command as the jenkins user:

ssh root@<application server address>

There will be a confirmation prompt for the first connection, just enter yes. This step is very important. If there is no manual connection confirmation for the first time, Jenkins will not be able to connect.

Configuring the Public over SSH plugin

Go to Manage Jenkins -> Configure System and fill in Publish over SSH settings.

Path to key: Fill in the path of the id_rsa key file just generated.
Name: Service name, fill in as you like.
HostName: The IP address or domain name of the application server.
Username: User identity for logging into the application server.
Remote Directory: The remote directory is the directory where the application is stored on the application server. Jenkins will copy the application to this directory. Please make sure this directory exists.

save~

3. Deploy Maven Project

Click New Item to create a new task, enter a task name, select Maven project, and click OK.

In General, check Discard old builds and set the maximum number of days and the maximum number of build files to be retained. Otherwise, the files generated by each build will be retained and take up disk space.

Configure the remote code repository address, from which Jenkins will pull the code. Note that if the prompt fails to read the repository, it may be:

• The public key is not added to the authorized_keys file of the remote code server. The above configuration of SSH login-free is for Jenkins to access the application server. Jenkins access to the code server also needs to be configured unless the application server and the code server are the same machine. If you use a code hosting platform such as Code Cloud or GitHub, there will be a corresponding SSH key settings page.
• The public key has been added to the corresponding files, but not manually connected for the first time. The solution is very simple. Manually clone the repository once as the jenkins user and confirm yes.

Check Add timestamps to the Console Output .

Fill in the Maven packaging instructions, -DMaven.test.skip=true means skipping the test.

Check Run only if build succeeds and select Send files or execute commands over SSH .

The next step is to copy the jar package from the Jenkins server to the application server and run it after setting up the build.

Name: Select the service you created earlier.
Source files: jar files generated after Maven packaging, that is, the programs to be copied to the application server for running. You can fill in multiple files, separated by commas.
Remove prefix: Ignore the prefix. We only need to copy the jar package under the target and do not need to generate a target directory on the application server.
Remote directory: The target folder will inherit the global settings. For example, the jar package will be copied to the /usr/local/app/demo directory.
Exec command: The command or script executed on the application server after the copy is completed.

save -> build build now . After the build is successful, open the browser to visit your site.

4. Conclusion

In fact, the whole process is not very complicated. Jenkins pulls code from the remote code library -> calls Maven instructions to package the project -> Jenkins copies the packaged files to the remote application server -> executes shell instructions on the remote application server to start the program. Both of Jenkins' remote operations were completed through SSH.
It is convenient to install Jenkins and Java through yum, but it is relatively troublesome to configure. You have to find the installation path yourself. When configuring SSH, you also need to use the jenkins user identity instead of root. If you use the unzip package method, you will have more freedom.

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.