Linux Administration: Simple Continuous Deployment System with Jenkins and Github

In this post I'll demonstrate a simple CD system, that based on a merge to the Master branch for a project on Github will package, push and deploy a small RESTfull application.

The setup consists of a single Jenkins server, a load balancer node running HAProxy and two API servers running Apache with the libapache2-mod-wsgi module to drive the Python Bottle microframework.

First let's create the local git repository:

File: gistfile1.txt ------------------- [workstation]$ ssh -T git@github.com [workstation]$ git ls-remote -h git@github.com:someuser/simple_rest_ci_pipline.git [workstation]$ git add * [workstation]$ git commit -m "Initializing the repository" [workstation]$ git push -u origin master

Create a new project on Github, and deploy your public key to it:

Next, test that you can connect using the deployed SSH key and push to the Master branch:

Let's build the Jenkins server:

File: gistfile1.txt ------------------- [jenkins-n01]$ wget -q -O - https://jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add - [jenkins-n01]$ sh -c 'echo deb http://pkg.jenkins-ci.org/debian binary/ > /etc/apt/sources.list.d/jenkins.list' [jenkins-n01]$ apt-get update && apt-get -y install jenkins git [jenkins-n01]$ /etc/init.d/jenkins start [jenkins-n01]$ iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

Once you login to Jenkins create a new project:

Or you can copy the following config file to /var/lib/jenkins/jobs/RESTfull-CI-Pipeline:

File: gistfile1.txt ------------------- [jenkins-n01]$ cd ~/jobs/RESTfull-CI-Pipeline [jenkins-n01]$ cat config.xml false https://github.com/kaivanov/simple_rest_ci_pipline/ 2 https://github.com/kaivanov/simple_rest_ci_pipline.git */master false true false false false false PACKAGE_NAME="simple-restfull-api.deb" PACKAGE_VERSION=$BUILD_NUMBER API1="XXX.XXX.XXX.XXX" API2="XXX.XXX.XXX>XXX" # Create the packe hierarchy and control file mkdir -p PACKAGE/DEBIAN mkdir -p PACKAGE/var/www/restfullapi cat > PACKAGE/DEBIAN/control <<EOF Package: simple-restfull-api Version: $PACKAGE_VERSION Priority: optional Architecture: all Maintainer: Konstantin Ivanov Description: Simple RESTfull API EOF cp $WORKSPACE/project/* $WORKSPACE/PACKAGE/var/www/restfullapi/ # Build the package dpkg-deb --build PACKAGE mv PACKAGE.deb $PACKAGE_NAME # Deploy the package. rsync --rsync-path="sudo rsync" -vaz $PACKAGE_NAME $API1:/tmp ssh -o stricthostkeychecking=no -o UserKnownHostsFile=/dev/null $API1 "sudo dpkg --install /tmp/$PACKAGE_NAME && sudo service apache2 reload" if [ "$?" -eq 0 ] then rsync --rsync-path="sudo rsync" -vaz $PACKAGE_NAME $API2:/tmp ssh -o stricthostkeychecking=no -o UserKnownHostsFile=/dev/null $API2 "sudo dpkg --install /tmp/$PACKAGE_NAME && sudo service apache2 reload" if [ "$?" -ne 0 ] then echo "Error deploying to node2, aborting ..." exit 1 fi else echo "Error deploying to node1, aborting ..." exit 1 fi false

Make sure you have the github plugin installed on Jenkins for this to work.

Lastly on the Github side, add a service that will call the Jenkins API when an event is triggered e.g. merge to Master:

Time to setup the API nodes:

File: gistfile1.txt ------------------- [api-n01/02]$ useradd -m -s /bin/bash jenkins [api-n01/02]$ sh -c 'echo jenkins ALL=(ALL:ALL) NOPASSWD:ALL > /etc/sudoers.d/100-ci-users' [api-n01/02]$ apt-get update [api-n01/02]$ apt-get install apache2 [api-n01/02]$ apt-get install python-pip [api-n01/02]$ pip install bottle [api-n01/02]$ apt-get install libapache2-mod-wsgi [api-n01/02]$ cat << EOF > /etc/apache2/sites-available/000-default.conf ServerName restfullapi-n01.example.net WSGIDaemonProcess restfullapi user=www-data group=www-data processes=1 threads=1 WSGIScriptAlias / /var/www/restfullapi/restfullapi.wsgi WSGIProcessGroup restfullapi WSGIApplicationGroup %{GLOBAL} Order deny,allow Allow from all EOF

And finally the load balancer node:

File: gistfile1.txt ------------------- [lb-n01]$ apt-get update && apt-get install haproxy [lb-n01]$ cat /etc/haproxy/haproxy.cfg global log /dev/log local1 log /dev/log local1 notice user haproxy group haproxy daemon defaults log global mode http option httplog option dontlognull contimeout 5000 clitimeout 50000 srvtimeout 50000 errorfile 400 /etc/haproxy/errors/400.http errorfile 403 /etc/haproxy/errors/403.http errorfile 408 /etc/haproxy/errors/408.http errorfile 500 /etc/haproxy/errors/500.http errorfile 502 /etc/haproxy/errors/502.http errorfile 503 /etc/haproxy/errors/503.http errorfile 504 /etc/haproxy/errors/504.http frontend http bind :80 reqadd X-Forwarded-Proto:\ http default_backend http_nodes backend http_nodes mode http balance leastconn option httpclose option forwardfor option redispatch option httpchk GET / cookie JSESSIONID prefix server api-n01 restfullapi-n01.example.net:80 check inter 1000 server api-n02 restfullapi-n02.example.net:80 check inter 1000

Now every time you merge a commit to Master, Github will POST to the Jenkins API, and Jenkins will execute the job, building a debian package, and deploying it to the API nodes.

To test the simple RESTfull API run:

Pages

Simple Continuous Deployment System with Jenkins and Github