Table of Contents
Introduction
Puppet is a configuration management tool that helps system administrators automate the provisioning, configuration and management of a server infrastructure. Planning ahead and using config management tools like Puppet can cut down on time spent repeating basic tasks and help ensure that configurations are consistent and accurate across your infrastructure.
Puppet comes in two varieties, Puppet Enterprise and open source Puppet. Both of them run on most Linux distributions, various UNIX platforms, and Windows.
In this tutorial, we will demonstrate how to install open source Puppet 4 in a master-agent setup on Ubuntu 16.04. In this setup, the Puppet master server—which runs the Puppet Server software—can be used to control all your other servers, called Puppet agent nodes.
Prerequisites
To follow this tutorial, you will need three Ubuntu 16.04 servers, each with a non-root user with sudo privileges. You can learn more about how to set up a user with sudo privileges in our Initial Server Setup with Ubuntu 16.04 guide.
One server will be the Puppet master. The Puppet master will run Puppet Server, which is resource intensive and requires:
- at least 4GB of memory
- at least 2 CPU cores
To manage larger infrastructures, the Puppet master will require more resources.
The other two servers will be Puppet agent nodes, managed by the Puppet master. We'll call them db1 and web1.
When these three servers are in place, you're ready to begin.
Step 1 — Configuring /etc/hosts
Puppet master servers and the nodes they manage need to be able to communicate with each other. In most situations, this will be accomplished using DNS, either configured on an externally hosted service or on self-hosted DNS servers maintained as part of the infrastructure.
DNS is its own domain of expertise, however, even on hosted services, so in order to focus on the fundamentals of Puppet itself and eliminate potential complexity in troubleshooting while we're learning, in this tutorial we'll use the /etc/hosts file instead.
On every machine
On each machine, edit the /etc/hosts file. At the end of the file, specify the Puppet master server as follows, substituting the IP address for _your_ Puppet master:
sudo nano /etc/hosts
[label /etc/hosts]
. . .
<^>puppet_ip_address<^> puppet
. . .
When you're done, save and exit.
Note: By default, Puppet agents will look for the Puppet master at puppet to make it easier to get Puppet set up. This means we _must_ use the name puppet in /etc/hosts. If puppet does not resolve to the Puppet master, the agents will not be able to make contact without configuring the server value in the agent's puppet.conf.
Step 2 — Installing Puppet Server
Puppet Server is the software that pushes configuration from the Puppet master to the other servers. It runs only on the Puppet master; the other hosts will run the Puppet Agent.
Note: The Ubuntu package manager _does_ contain packages for Puppet, but many administrators need to manage multiple operating systems and versions. In this case, working with the official Puppet Labs repositories can simplify administration by allowing you to maintain the same Puppet version on all systems.
We'll enable the official Puppet Labs collection repository with these commands:
curl -O https://apt.puppetlabs.com/puppetlabs-release-pc1-xenial.deb
sudo dpkg -i puppetlabs-release-pc1-xenial.deb
sudo apt-get update
When apt-get update is complete, ensuring that we'll be pulling from the Puppet Labs repository, we'll install the puppetserver package:
sudo apt-get install puppetserver
Press Y to proceed. Once installation is complete, and before we start the server, we'll take a moment to configure the memory.
Configure memory allocation
By default, Puppet Server is configured to use 2 GB of RAM. You can customize this setting based on how much free memory the master server has and how many agent nodes it will manage.
To customize it, open /etc/default/puppetserver:
sudo nano /etc/default/puppetserver
Then find the JAVA_ARGS line, and use the -Xms and -Xmx parameters to set the memory allocation. We'll increase ours to 3 gigabytes:
[label /etc/default/puppetserver]
JAVA_ARGS="-Xms<^>3<^>g -Xmx<^>3<^>g -XX:MaxPermSize=256m"
Save and exit when you're done.
Open the firewall
When we start Puppet Server, it will use port 8140 to communicate, so we'll ensure it's open:
sudo ufw allow 8140
Next, we'll start Puppet server.
Start Puppet server
We'll use systemctl to start Puppet server:
sudo systemctl start puppetserver
This will take some time to complete.
Once we're returned to the command prompt, we'll verify we've succeeded since systemctl doesn't display the outcome of all service management commands:
sudo systemctl status puppetserver
We should see a line that says "active (running)" and the last line should look something like:
[secondary_label Output]
Dec 07 16:27:33 puppet systemd[1]: Started puppetserver Service.
Now that we've ensured the server is running, we'll configure it to start at boot:
sudo systemctl enable puppetserver
With the server running, now we're ready to set up Puppet Agent on our two agent machines, db1 and web1.
Step 3 — Installing the Puppet Agent
The Puppet agent software must be installed on any server that the Puppet master will manage. In most cases, this will include every server in your infrastructure.
Note: The Puppet agent can run on all major Linux distributions, some UNIX platforms, and Windows. Installation instructions vary on each OS. Directions to install the Puppet agent on CentOS are available progressiverobot.com, and you can find directions for the complete set of installation targets in the Puppet Reference Manual.
Enable the official Puppet Labs repository
First we'll enable the official Puppet Labs collection repository with these commands:
[environment second]
wget https://apt.puppetlabs.com/puppetlabs-release-pc1-xenial.deb
sudo dpkg -i puppetlabs-release-pc1-xenial.deb
sudo apt-get update
Install the Puppet agent package
Then, we'll install the puppet-agent package:
[environment second]
sudo apt-get install puppet-agent
We'll start the agent and enable it to start on boot:
[environment second]
sudo systemctl start puppet
sudo systemctl enable puppet
Finally, we'll repeat these steps on web1:
[environment third]
wget https://apt.puppetlabs.com/puppetlabs-release-pc1-xenial.deb
sudo dpkg -i puppetlabs-release-pc1-xenial.deb
sudo apt-get update
sudo apt-get install puppet-agent
sudo systemctl enable puppet
sudo systemctl start puppet
Now that both agent nodes are running the Puppet agent software, we will sign the certificates on the Puppet master.
Step 4 — Signing Certificates on Puppet Master
The first time Puppet runs on an agent node, it sends a certificate signing request to the Puppet master. Before Puppet Server will be able to communicate with and control the agent node, it must sign that particular agent node's certificate.
List current certificate requests
To list all unsigned certificate requests, run the following command on the Puppet master:
sudo /opt/puppetlabs/bin/puppet cert list
There should be one request for each host you set up, that looks something like the following:
[secondary_label Output:]
"db1.localdomain" (SHA256) 46:19:79:3F:70:19:0A:FB:DA:3D:C8:74:47:EF:C8:B0:05:8A:06:50:2B:40:B3:B9:26:35:F6:96:17:85:5E:7C
"web1.localdomain" (SHA256) 9D:49:DE:46:1C:0F:40:19:9B:55:FC:97:69:E9:2B:C4:93:D8:A6:3C:B8:AB:CB:DD:E6:F5:A0:9C:37:C8:66:A0
A + in front of a certificate indicates it has been signed. The absence of a plus sign indicates our new certificate has not been signed yet.
Sign requests
To sign a single certificate request, use the puppet cert sign command, with the hostname of the certificate as it is displayed in the certificate request.
For example, to sign db1's certificate, you would use the following command:
sudo /opt/puppetlabs/bin/puppet cert sign <^>db1.localdomain<^>
Output similar to the example below indicates that the certificate request has been signed:
[secondary_label Output:]
Notice: Signed certificate request for <^>db.localdomain<^>
Notice: Removing file Puppet::SSL::CertificateRequest <^>db1.localdomain<^> at '/etc/puppetlabs/puppet/ssl/ca/requests/<^>db1.localdomain<^>.pem'
The Puppet master can now communicate and control the node that the signed certificate belongs to. You can also sign all current requests at once.
We'll use the --all option to sign the remaining certificate:
sudo /opt/puppetlabs/bin/puppet cert sign --all
Now that all of the certificates are signed, Puppet can manage the infrastructure. You can learn more about managing certificates in the How to Manage Puppet 4 Certificates cheat sheet.
Step 5 — Verifying the Installation
Puppet uses a domain-specific language to describe system configurations, and these descriptions are saved to files called "manifests", which have a .pp file extension. You can learn more about these in the Getting Started with Puppet Code: Manifests and Modules guide, but for now we'll create a brief directive to verify that the Puppet Server can manage the Agents as expected.
We'll begin by creating the default manifest, site.pp, in the default location:
sudo nano /etc/puppetlabs/code/environments/production/manifests/site.pp
We'll use Puppet's domain-specific language to create a file called it_works.txt on agent nodes located in the tmp directory which contains the public IP address of the agent server and sets the permissions to-rw-r--r--:
[label site.pp example]
file {'/tmp/it_works.txt': # resource type file and filename
ensure => present, # make sure it exists
mode => '0644', # file permissions
content => "It works on ${ipaddress_eth0}!\n", # Print the eth0 IP fact
}
By default Puppet Server runs the commands in its manifests by default every 30 minutes. If the file is removed, the ensure directive will cause it to be recreated. The mode directive will set the file permissions, and the content directive add content to the directive.
We can also test the manifest on a single node using puppet agent --test. Note that --test is not a flag for a dry run; if it's successful, it will change the agent's configuration.
Rather than waiting for the Puppet master to apply the changes, we'll apply the manifest now on db1:
[environment second]
sudo /opt/puppetlabs/bin/puppet agent --test
The output should look something like:
[secondary_label Output]
[environment second]
Info: Using configured environment 'production'
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Info: Caching catalog for db1.localdomain
Info: Applying configuration version '1481131595'
Notice: /Stage[main]/Main/File[/tmp/it_works.txt]/ensure: defined content as '{md5}acfb1c7d032ed53c7638e9ed5e8173b0'
Notice: Applied catalog in 0.03 seconds
When it's done, we'll check the file contents:
[environment second]
cat /tmp/it_works.txt
[secondary_label Output]
[environment second]
It works on <^>203.0.113.0<^>!
Repeat this for web1 or, if you prefer, check back in half an hour or so to verify that the Puppet master is running automatically.
Note: You can check the log file on the Puppet master to see when Puppet last compiled the catalog for an agent, which indicates that any changes required should have been applied.
tail /var/log/puppetlabs/puppetserver/puppetserver.log
[secondary_label Output excerpt]
. . .
2016-12-07 17:35:00,913 INFO [qtp273795958-70] [puppetserver] Puppet Caching node for web1.localdomain
2016-12-07 17:35:02,804 INFO [qtp273795958-68] [puppetserver] Puppet Caching node for web1.localdomain
2016-12-07 17:35:02,965 INFO [qtp273795958-68] [puppetserver] Puppet Compiled catalog for web1.localdomain in environment production in 0.13 seconds
. . .
Congratulations! You've successfully installed Puppet in Master/Agent mode.
Conclusion
Now that you have a basic agent/master Puppet installation, you are ready to learn more about how to use Puppet to manage your server infrastructure. Check out the following tutorial: Getting Started With Puppet Code: Manifests and Modules.
