Install a Jenkins on Ubuntu system

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                                                   Jenkins Environment
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Prerequisites:     Install Java and Nignx (or Apache )

#Install Java

　　- Check if Java is not already installed:

java -version

　　- If it returns "The program java can be found in the following packages", Java hasn't been installed yet, so execute the following command:

sudo apt-get install default-jre

# Setting up an Nginx Proxy for port 80 -> 8080
　　- Install Nginx

sudo apt-get install nginx -y

　　- Remove default configuration

　　　　cd /etc/nginx/sites-available
　　　　sudo rm default ../sites-enabled/default

　　- Create new configuration for Jenkins

　　      (Edit jenkins file in the /etc/nginx/sites-available/ directory. )

vim jenkins

　　upstream app_server {
　　　　server 127.0.0.1:8080 fail_timeout=0;
　　}

　　server {
　　　　listen 80;
　　　　listen [::]:80 default ipv6only=on;
　　　　server_name jenkins.yourcompany.com;

　　　　location / {
　　　　　　proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
　　　　　　proxy_set_header Host $http_host;
　　　　　　proxy_redirect off;

　　　　　　if (!-f $request_filename) {
　　　　　　　　proxy_pass http://app_server;
　　　　　　　　break;
　　　　　　}
　　　　}
　　}

　　- Link your configuration from sites-available to sites-enabled:

sudo ln -s /etc/nginx/sites-available/jenkins /etc/nginx/sites-enabled/

　　- Restart Nginx

sudo service nginx restart

# use jenkins user goes to install jenkins service

　　- Install jenkins

su - jenkins

wget -q -O - http://pkg.jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add -

sudo sh -c 'echo deb http://pkg.jenkins-ci.org/debian binary/ > /etc/apt/sources.list.d/jenkins.list'

sudo apt-get update

sudo apt-get install jenkins


sudo systemctl enable jenkins

　　- check the service whether is running normally:

sudo service jenkins status

　　- run Jenkins:

sudo service jenkins start

　　- stop Jenkins:

sudo service jenkins stop

　　- restart Jenkins:

sudo service jenkins restart

#Install Directory：   /var/lib/jenkins

#Log Directory：  /var/log/jenkins/jenkins.log

tail -f /var/log/jenkins/jenkins.log

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