Start installing *nix agents

When a node is managed by Puppet, it runs a Puppet agent application, commonly called an agent. In this guide you install a *nixPuppet agent, which regularly pulls configuration catalogs from a Puppet master and applies them locally. This section includes how to sign the agent certificate request in the console.

These instructions assume you've installed PE.

How does a Puppet agent work?

Agents ensure that resources in a node stay in their desired state.

Periodically, a Puppet agent sends facts to a Puppet master and requests a catalog. The master compiles the catalog using several sources of information, and returns the catalog to the agent.

Once it receives a catalog, the agent applies it by checking each resource the catalog describes. If it finds any resources that are not in their desired state, the agent makes any changes necessary to correct them. (Or, in no-op mode, it reports on what changes would have been needed.)

After applying the catalog, the agent submits a report to its master. Reports from all the agents are stored in PuppetDB and can be accessed in the PE console.

Step 1a: Install an agent with the same OS and architecture as the Puppet master

Follow these steps if your agent node and your Puppet master have the same operating system and architecture. Otherwise, go to Step 1b.

Log into your agent node and run:
```
curl -k https://<MASTER HOSTNAME>:8140/packages/current/install.bash | sudo bash                
```
This script detects the agent's operating system, sets up an apt, yum, or zipper repo that refers back to the Puppet master, and then pulls down and installs the puppet-agent packages.
After installation is complete, approve the certificate request to approve the new agent's certificate request in the console.

Step 1b: Install an agent with a different OS and architecture than the Puppet master

Follow these steps if your agent node and your Puppet master do not have the same operating system and architecture. Otherwise, go to Step 1a.

This example describes adding an agent running Debian 6 on AMD64 hardware.As you complete the steps, modify the commands to match your agent's OS and architecture.

In the console, click Classification, and in the PE Infrastructure node group, select the PE Master group.
On the Configuration tab, in the Add new class field, enter pe_repo, and select the class pe_repo::platform::debian_6_amd64 — or whichever class matches your agent — from the list of classes.

The repo classes are listed as pe_repo::platform::<agent_os_version_architecture>
Click Add class.

The class you selected now appears in the list of classes for the PE Master group, but it has not yet been configured on your nodes. For that to happen, you need to kick off a Puppet run.
From the command line of your master, run puppet agent -t.
SSH into your agent node, and run the following:

curl -k https://<master.example.com>:8140/packages/current/install.bash | sudo bash

If you want to install a version of PE other than the most recent release, replace current in the script with a specific PE version number, in the form of 2016.x.x.

Depending on your platform, the method for downloading the script might vary.

The installer installs and configures the Puppet Enterprise agent.
After installation is complete, approve the certificate request to approve the new agent's certificate request in the console.

Step 2: Approve the certificate request

During installation, the agent node contacts the Puppet master and requests a certificate. To add the node to the console and to start managing its configuration, you must approve its certificate request.

In the console, load a list of currently pending node requests by clicking Unsigned certs.
Click the Accept All button to approve the request and add the node.

The Puppet agent can now retrieve configurations from the master the next time Puppet runs.

Step 3: Test the Puppet agent node

You can wait until Puppet runs automatically, or you can manually trigger Puppet runs.

By default, the agent fetches configurations from the Puppet master every 30 minutes. (You can configure this interval in the puppet.conf file with the runinterval setting.) However, you can manually trigger a Puppet run from the command line at any time.

On the agent, log in as root and run puppet agent --test. This triggers a single Puppet run on the agent with verbose logging.
If you receive a -bash: puppet: command not found error, then the directory that PE installs its binaries in, /opt/puppetlabs/bin, isn’t included in your default $PATH. To include these binaries in your default $PATH, add them by running PATH=/opt/puppetlabs/bin:$PATH;export PATH.
Note the long string of log messages, ending with this message: Notice: Applied catalog in [...] seconds.

You are now fully managing the agent node! It has checked in with the Puppet master for the first time and received its configuration info. It continues to check in and fetch new configurations every 30 minutes.

Next, learn how to configure your agents with Puppet code, beginning with pre-built chunks of Puppet code called modules.