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‎_includes/hired3.html

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<center>
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This video sponsored by <a href="http://www.hired.com/devopslibrary">Hired.com</a>
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<br><span style="font-size: 80%;"><i>Thank you for supporting the DevOps Community!</i></span>
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‎_includes/subscribe.html

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<p>If you love our videos and want to help us as well as join our high scores list at the end of each video, please support us at patreon.com/devopslibrary.</p><br/>
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<p>If you love our videos and want to help us as well as join our high scores list at the end of each video, please support us at <a href="https://www.patreon.com/devopslibrary">patreon.com/devopslibrary.</a></p><br/>
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‎_posts/2016-28-16-DevOps For Beginners Introduction.markdown renamed to ‎_posts/2016-7-28-DevOps For Beginners Introduction.markdown

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‎_posts/2016-8-22-Jenkins CCJPE HA.markdown

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---
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layout: post
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title: "CCJPE: Jenkins High Availability"
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date: 2016-8-22 12:00:00 -0500
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categories: Jenkins
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permalink: lessons/jenkins-ha
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excerpt: "Learn how to set up Jenkins HA!"
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weight: 11
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image: 'jenkinscourse.png'
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difficulty: hard
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---
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{% include youtube.html id="zHavme2iaFA" %}
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{% include hired3.html %}
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1. Table of Contents
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{:title="Table of Contents"}
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{:toc}
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Introduction
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------------
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Welcome to the DevOps Library! This is Samantha, and today we're going to set
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up the Enterprise edition of Jenkins! Up until now, we've only been using the
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open-source version, but for the rest of this course, we'll mainly be focusing
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on enterprise functionality.
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Additionally, we're going to set up Jenkins the RIGHT way, in full HA mode,
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with two masters sitting behind a load balancer.
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Before we begin, we'd like to give a quick shout out to
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[Hired.com](http://www.hired.com/devopslibrary) for being kind enough to sponsor
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our Jenkins course. If you aren’t familiar with Hired, it’s a great company that
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completely reverses the traditional job search, by having companies apply to
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you, instead of you always doing the tedious work of applying.
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Thousands of companies look to Hired to connect with the best of the best in our
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field, like you! OH. And if you do end up signing up through our [personal link](http://www.hired.com/devopslibrary), and landing a new job, Hired will give you a 2k bonus for being a loyal
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supporter of the DevOps Library!
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Getting Started
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---------------
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Alright, let’s go ahead and get started. First, we're going to spin up two
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Ubuntu 14.04 instances on AWS. We recommend spinning them up in two different
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availability zones, that way Jenkins can survive an entire Amazon zone being
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unavailable.
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To speed up the process, we have two cloud config files that you can use below,
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the only difference between them is the hostname.
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[https://www.devopslibrary.com/scripts/jenkins01.yaml](https://www.devopslibrary.com/scripts/jenkins01.yaml)
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[https://www.devopslibrary.com/scripts/jenkins02.yaml](https://www.devopslibrary.com/scripts/jenkins02.yaml)
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``` yaml
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#cloud-config
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hostname: jenkins01
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fqdn: jenkins01
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manage_etc_hosts: true
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runcmd:
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- add-apt-repository ppa:webupd8team/java -y
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- echo 'deb http://nectar-downloads.cloudbees.com/nectar/debian binary/' >> /etc/apt/sources.list
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- echo debconf shared/accepted-oracle-license-v1-1 select true | debconf-set-selections
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- echo debconf shared/accepted-oracle-license-v1-1 seen true | debconf-set-selections
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- wget -q -O - http://nectar-downloads.cloudbees.com/nectar/debian/cloudbees.com.key | sudo apt-key add -
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- apt-get update
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- apt-get install oracle-java8-installer nfs-common -y
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```
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Configuration
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-------------
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If you'd prefer to configure both instances manually, the only thing we're doing
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in the cloud config is installing Java 8, NFS support, and adding the Jenkins
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enterprise repositories. Make sure you don't install Jenkins yet as we do need
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to configure shared storage.
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Jenkins High Availability requires that both masters share an identical
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"$JENKINS_HOME" folder. Technically that means that you could MacGyver
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something using rsync or some other method, but we HIGHLY recommend using shared
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storage.
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Setting up Shared Storage
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-------------------------
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For us, since we're on AWS, we'll use Amazon's EFS service to create a new NFS
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shared file system. We do need to make sure we have the right availability
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zones and security groups selected, but overall it's very easy to set up.
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After the EFS share comes up, click the "DNS Names" link. You should see a DNS
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entry for each availability zone, be sure to note them down, as we'll use them
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to mount the storage to our instances.
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Alright, let's go ahead and SSH into both Jenkins VMs.
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Next, run:
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``` bash
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mkdir /var/lib/jenkins
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```
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That will create a directory for our Jenkins home. Next, open up your
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`/etc/fstab` file and add the following line:
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``` bash
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us-yourRegion-URL-thing.amazonaws.com:/ /var/lib/jenkins nfs4 rw,hard,intr 0 2
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```
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This is the line where we'll need to make sure we use the right DNS name for
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each zone, but other than it's pretty easy. Alright, go ahead and save the
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file, then run "mount -a" to mount the storage, or you can just restart the
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instance.
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You can also run `df -h` if you'd like to double check that the NFS share
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mounted correctly. If it is, you'll see it listed like we do here.
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Installing Cloudbees Jenkins Platform
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-------------------------------------
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Ok, at this point, make sure you've got our NFS share mounted on both instances,
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then run an `apt-get install jenkins` on **jenkins01**. Once the install
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completes, you can access the Jenkins web UI on port 8080.
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Since this is the enterprise version of Jenkins, you will need to request a
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trial license before you can do anything else. After you complete the
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registration, go ahead and do a Jenkins install on the second AWS instance.
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Jenkins High Availability Overview
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----------------------------------
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While that's installing, let's talk a little more in depth about what Jenkins
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High Availability is, and what it is not. Essentially, the Enterprise Jenkins
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HA plugin uses Jgroups to configure active/passive high availability when it
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detects that two masters are sharing the same Jenkins home.
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Because we installed Jenkins on the **Jenkins01** instance first, it'll start
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out as our "primary" instance.
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If you try to access **Jenkins02** on port 8080 on the other hand, you'll see a
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message letting you know that the node is standing by in case the primary
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instance fails. Effectively, a Jenkins fail-over results in the shutting down
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of the current Jenkins master, followed by it starting up on a second server.
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Failover Overview
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-----------------
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Because both masters share the same *$JENKINS_HOME*, a failover has the
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following characteristics. Tje following will all survive a failover event:
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* Jenkins Settings
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* Configuration of Jobs & Users
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* Fingerprints
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* Records of Builds
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* Artifacts
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* Test Reports
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However, by default, any builds that were in-progress won't survive. Don't worry--
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Cloudbees has released two plugins to address this issue. The [Restart Aborted Builds](https://www.cloudbees.com/products/cloudbees-jenkins-platform/enterprise-edition/features/restart-aborted-builds-plugin) plugin makes it easy to kick off any jobs that were
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running during a restart or failover event.
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Or, by using the [Long-Running Build](https://www.cloudbees.com/products/cloudbees-jenkins-platform/enterprise-edition/features/long-running-build-plugin) plugin, you can create jobs that survive master restarts, although
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you'll have to change your jobs project type from FreeStyle to "Long Running
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Projects".
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HA Health Checks
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----------------
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Alright, at this point, you should have two masters configured. Visit both of
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the Jenkins master URLs in your web browser, followed by **/ha/health-check**.
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**Jenkins01** should return *Running as primary*, and **Jenkins02** should
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return *Running as standby*. Excellent job!! If we were to shut down or have
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**Jenkins01** crash, **Jenkins02** would automatically take its place as primary.
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The problem though is that our users would still have to change URLs after any
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failover. That's why we still have one final step; we need to set up a load
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balancer!
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Setting up a Load Balancer
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--------------------------
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If you're not using AWS, your best bet is probably going to be something like
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[HAproxy](http://www.haproxy.org/), or even an [F5](https://f5.com/products/big-ip)
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if you have the budget. Thankfully for us, we can quickly set up an [Amazon ELB](https://aws.amazon.com/elasticloadbalancing/), or "Elastic Load Balancer".
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Let's go ahead and do that now.
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On your AWS console, click "Load Balancers", then "Create Load Balancer".
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Select "Classic Load Balancer", as we'll need to route both HTTP for the web
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interface, as well as a TCP port for JNLP.
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Feel free to name the balancer whatever you'd like, then use port 80 for the
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listener port, and port 8080 on the instances. That way any traffic that comes
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in on port 80 to the load balancer will automatically be redirected to port 80
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on the primary instance. You'll also want to add a TCP port for JNLP.
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We like to use 10001, but it doesn't matter what you use as long as it matches
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what you configure under your Global Security settings.
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Configure ELB Health Check
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--------------------------
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Next, after you select a security group, we need to set up a health check.
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This is how Amazon determines to which instance traffic should flow. Remember
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that **/ha/health-check** URL we went to earlier? Use that for the ping path.
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That way, the only instance that AWS will see as healthy is the one currently
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running as primary.
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You'll also want to lower the response timeout, interval, and healthy threshold.
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If you copy the settings we have here, and the primary master goes down, you
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should only experience a minute or two of downtime in the event of a failover,
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give or take depending on how many plugins and jobs you're using.
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Alright, add the two instances, then finish creating the load balancer.
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Within a few minutes, the status of the load balancer should show one of two
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instances as healthy. Once you see that, go ahead and pull up the load balancer
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DNS name up in your browser.
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There we go!!! Great job!! You've successfully set up the Cloudbees Enterprise
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Jenkins platform, and not only that, we're running it in full high availability
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mode!!! Aside from a few performance and security tweaks, these guys are ready
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for production use!! Right now we should be running off of **Jenkins01**.
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Testing Failover
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----------------
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If you'd like to test a failover, go ahead and crash that VM or power it off,
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then refresh the URL to our load balancer. Within a few minutes, the secondary
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master should automatically take over as the primary, and our ELB will now point
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us to the new master. There we go!! Cool huh? You've done a fantastic job in
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this episode, thank you for watching!
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Conclusion & Shoutout
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---------------------------------
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We'd like to give another special shout out to [Hired.com](http://www.hired.com/devopslibrary) for
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sponsoring this course. If you're into DevOps, there's a pretty good chance
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you've had to deal with pushy recruiters and countless emails, as well as spent
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many hours searching for DevOps opportunities.
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The reason we love using [Hired.com](http://www.hired.com/devopslibrary) is that
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it completely reverses this situation and puts the power back in your hands, by
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having companies send you interview requests that you can choose to pursue.
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(They even come with upfront salary and equity!)
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By having you fill out information that is specific to what you’re looking for
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and your individual strengths and talents, it ensures that the only companies
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you'll hear from will be a great fit for you. Plus, Hired is entirely free, and
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they’ll even give you a $2,000 bonus after you land a job, using our DevOps
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Library link!
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We highly recommend giving them a shot, they do a fantastic job, especially for
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the DevOps community.
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Thanks for Watching!
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--------------------
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[Subscribe to our YouTube channel](https://www.youtube.com/channel/UCOnioSzUZS-ZqsRnf38V2nA?sub_confirmation=1) or follow [DevOpsLibrary on Twitter](https://twitter.com/intent/user?screen_name=devopslibrary).
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