5.3.5. HOWTO Set Up SIMP’s External Node Classifier¶

An External Node Classifier, ENC, can be used to determine what Puppet environment is used by a node.

SIMP provides a simple, YAML-based ENC, /usr/local/bin/set_environment, available from the simp-utils RPM. That package will already be installed on your system, if you installed the SIMP server from a SIMP ISO or from RPM.

To use this script for your ENC, do the following as root:

Ensure the script can be executed by the puppetserver.

chmod g+rX /usr/local/bin/set_environment
chgrp puppet /usr/local/bin/set_environment

Configure Puppet to use this script as an ENC

Set the following in the [server] section of /etc/puppetlabs/puppet/puppet.conf:
1. Add or change the line node_terminus to exec.
2. Set the external_nodes entry to /usr/local/bin/set_environment.
The resulting lines should look something like this:
```
...
[server]
...
node_terminus = exec
external_nodes = /usr/local/bin/set_environment
...
```
Add a file /etc/puppetlabs/puppet/environments.yaml to your system.

This file defines the mapping of nodes to environments.
- Each rule in this file should have the form
  
  <regular expression or FQDN>: 'environment name'.
- The rules are processed from top down, and the first match wins.
For example,
```
# The puppet server will use the production environment
'puppet.my.domain':            'production'

# Any node in my.domain whose FQDN begins with test will use the test environment
'/^test([0-9])+\.my\.domain/': 'test'

# Default to the production environment in all other cases
'/^.*$/':                      'production'
```
To verify the file is properly formatted and yields the classification desired run the script manually with a node’s FQDN. It should return

environment: <node's Puppet environment name>

Using the above environments.yaml file, the following command should return

environment: test
```
/usr/local/bin/set_environment test11.my.domain
```

Ensure the puppetserver can access the ENC’s configuration file

chmod g+rX /etc/puppetlabs/puppet/environments.yaml
chgrp puppet /etc/puppetlabs/puppet/environments.yaml

Restart the puppetserver service

# On EL7
systemctl restart puppetserver

For more information on ENCs, please see Puppet’s ENC documentation.