Jenkins 101: Getting Started

Jenkins 101: Getting Started
By
R. Geoffrey Avery
FOSSCON – Philadelphia 2016
YAPC::EU – Cluj 2016

What is Jenkins
● Tool for continuous integration/development
● A fork from Hudson
● Fire jobs manually, on a schedule, on commit
● Uses Java and Tomcat to do its work
● In same game as TravisCI

Install Jenkins
sudo wget -q -O - https://jenkins-ci.org/debian/jenkins-
ci.org.key | apt-key add -
sudo apt-get install jenkins
#------
sudo wget -O /etc/yum.repos.d/jenkins.repo
http://pkg.jenkins-ci.org/redhat/jenkins.repo
sudo rpm --import https://jenkins-ci.org/redhat/jenkins-
ci.org.key
sudo yum install jenkins
● https://wiki.jenkins-ci.org/display/JENKINS/Installing+Jenkins

Configure Node
● If you are on a small server Nerf these or
provide more resources

How to add users
● https://wiki.jenkins-ci.org/display/JENKINS/Standard+Security+Setup
● Make sure your user has powers before you deny everyone full power

Get to adding users
● Manage Jenkins → Configure Global Security

Enable Security
● Turn on security
● Let Jenkins manage
● Anyone can still get in
(don't lock yourself
out)

Become a User
● Go create yourself a user

Enable Matrix Security
● Pick matrix
● Add yourself
● Give yourself full power

Plugins
● Jenkins supports many plugins to add features
● Can generally install new plugin without a
restart
● To upgrade or remove a restart usually needed

HTML Publisher Plugin
● https://wiki.jenkins-ci.org/display/JENKINS/HTML+Publisher+Plugin

More good plugins
https://wiki.jenkins-ci.org/display/JENKINS/
● NodeLabel+Parameter+Plugin
● Validating+String+Parameter+Plugin
● Git+Plugin (need git 1.7.9+)

Job to grep configurations
● Jenkins stores job as
…/jobs/jobname/config.xml
● Pain to search across many jobs
● This sample job will grep just config.xml files
● Will make html report of what is found

Schedule for Periodic Builds
This field follows the syntax of cron (with minor differences). Specifically, each line consists of 5
fields separated by TAB or whitespace:
MINUTE HOUR DOM MONTH DOW
MINUTE Minutes within the hour (0–59)
HOUR The hour of the day (0–23)
DOM The day of the month (1–31)
MONTH The month (1–12)
DOW The day of the week (0–7) where 0 and 7 are Sunday.
To specify multiple values for one field, the following operators are available. In the order of
precedence,
* specifies all valid values
M-N specifies a range of values
M-N/X or */X steps by intervals of X through the specified range or whole valid range
A,B,...,Z enumerates multiple values
To allow periodically scheduled tasks to produce even load on the system, the symbol H (for “hash”)
should be used wherever possible. For example, using 0 0 * * * for a dozen daily jobs will cause a
large spike at midnight. In contrast, using H H * * * would still execute each job once a day, but not
all at the same time, better using limited resources.
The H symbol can be used with a range. For example, H H(0-7) * * * means some time between 12:00 AM
(midnight) to 7:59 AM. You can also use step intervals with H, with or without ranges.
The H symbol can be thought of as a random value over a range, but it actually is a hash of the job
name, not a random function, so that the value remains stable for any given project.

Schedule for School Night
H H(6-11) * * 1-5
#Once each school night between 10pm-4am San Francisco /
1am-7am Wilmington / 6am-noon London (an hour later in
summer)
#If someone does something foolish on Friday or Saturday the
site won't be broken over the weekend because of the update
● Schedule jobs with a very cron like syntax
● Use 'H' to let jenkins pick for better distribution

Add a slave node
● Not all work needs to or should run on master
● Slaves can be on same server or many
● Make a user (groupadd, useradd)
● Install Java (apt-get, yum, or ?)
● Setup ssh for connections...

Create ssh key for slave
jenkins@localhost:~$ mkdir .ssh
jenkins@localhost:~$ cd .ssh
jenkins@localhost:~/.ssh$ chmod 0700 .
jenkins@localhost:~/.ssh$ ssh-keygen -C "jenkins to slave mrprod"
-f jenkins_to_mrprod
jenkins@localhost:~/.ssh$ ls -aFl
total 16
drwx------ 2 jenkins jenkins 4096 Jun 1 12:53 ./
drwxr-xr-x 14 jenkins jenkins 4096 Jun 1 12:51 ../
-rw------- 1 jenkins jenkins 1679 Jun 1 12:53 jenkins_to_mrprod
-rw-r--r-- 1 jenkins jenkins 399 Jun 1 jenkins_to_mrprod.pub

.ssh/config
host sample-mrprod
hostname sample.dynalias.org
user mrprod
identityfile ~/.ssh/jenkins_to_mrprod
● Let the master call slave from command line
● Will need ForwardAgent and Proxy Command if
you need to tunnel through a middle box

Give ssh key to slave
root@localhost:/home/mrprod# sudo su mrprod
localhost:~> pwd
/home/mrprod
localhost:~> mkdir .ssh
localhost:~> chmod 0700 .ssh
localhost:~> cd .ssh
localhost:~/.ssh> touch authorized_keys
localhost:~/.ssh> chmod 0600 authorized_keys
#then put the public key in authorized_keys
● ssh will not work if you forget the chmod step

Starting and Stopping
http://sample.dynalias.org:8080/quietDown
http://sample.dynalias.org:8080/cancelQuietDown
${JENKINSURL}/${ACTION}
#------
$ sudo /etc/init.d/jenkins restart
● Other valid choices for the ACTION: start|stop|status|restart|
force-reload
● A good idea to quietDown first so you don't stop jobs in progress

Thank You
Slides will be found at
http://platypiventures.com/perl/present
And the conference website

Slides of the Rigged Demo
These were replaced by the live demo

Source Code Settings
● Git needs a plugin

Add Code to Do Something
● Add a shell to do the real work. Today with bash, but
also supports Groovy and anything you can call

Script Part 1
#!/bin/bash
# make sure we have place to write the output
# if no directory build one, blow away a file it it is in the way
if [[ ! -d $WORKSPACE/output ]] ; then
if [[ -e $WORKSPACE/output ]] ; then
rm $WORKSPACE/output
fi
mkdir $WORKSPACE/output
fi
ls -aFlR $WORKSPACE
report="$WORKSPACE/output/found.html"
hostname
whoami
pwd
cd ../../jobs
pwd
echo "<h1>$Pattern</h1> ( $Settings )<hr>" > $report

Script Part 2
jenkinsgrep () {
for dir in * ; do
echo "nn--------------- $dir"
local results=$(grep $Settings $Pattern $dir/config.xml)
if [[ -n $results ]]; then
echo $results
# echo "<h2>$dir</h2>" >> $report
echo "<h2><a href='${JENKINS_URL}job/$dir/configure'>$dir</a></h2>" >> $report
echo "<pre>$results</pre>" >> $report
fi
done
}
jenkinsgrep

The End (Again)
Check github for slides and the config.xml files for
the jobs discussed

Jenkins 101: Getting Started

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