Use an independent intermediate certificate authority

The built-in Puppet certificate authority automatically generates a root and intermediate certificate, but if you need additional intermediate certificates or prefer to use a public authority CA, you can set up an independent intermediate certificate authority. You must complete this configuration during installation.

This method requires more manual maintenance than the default certificate authority setup. With an external chain of trust, you must monitor for and promptly update expired CRLs, because an expired CRL anywhere in the chain causes certificate validation failures. To manage an external CRL chain:

Take note of the Next Update dates of the CRLs for your entire chain of trust.
Submit updated CRLs to Puppet Server using the Certificate Revocation List endpoint.
Configure agents to download CRL updates by setting crl_refresh_interval in the puppet_enterprise::profile::agent class.

Collect the PEM-encoded certificates and CRLs for your organization's chain of trust, including the root certificate, any intermediate certificates, and the signing certificate. (The signing certificate might be the root or intermediate certificate.)
Create a private RSA key, with no passphrase, for the Puppet CA.
Create a PEM-encoded Puppet CA certificate.
1. Create a CSR for the Puppet CA.
2. Generate the Puppet CA certificate by signing the CSR using your external CA.
  Ensure the CA constraint is set to true and the keyIdentifier is composed of the 160-bit SHA-1 hash of the value of the bit string subjectPublicKeyfield. See RFC 5280 section 4.2.1.2 for details.

Concatenate all of the certificates into a PEM-encoded certificate bundle, starting with the Puppet CA cert and ending with your root certificate.

Concatenate all of the CRLs into a PEM-encoded CRL chain, starting with any optional intermediate CA CRLs and ending with your root certificate CRL.
```
-----BEGIN X509 CRL-----
<OPTIONAL INTERMEDIATE CA CRLs>
-----END X509 CRL-----
-----BEGIN X509 CRL----- 
<ROOT CA CRL> 
-----END X509 CRL-----
```
The PE installer automatically generates a Puppet CRL during installation, so you don't have to manage the Puppet CRL manually.
Copy your CA bundle (from step 4), CRL chain (from step 5), and private key (from step 2) to the node where you're installing the primary server.
Allow access to your private key only from the PE installation process, which runs as root.
Install PE using a customized pe.conf file with signing_ca parameters: ./puppet-enterprise-installer -c <PATH_TO_pe.conf>
In your customized pe.conf file, you must include three keys for the signing_ca parameter: bundle, crl_chain, and private_key.
```
{
 "pe_install::signing_ca": {
   "bundle": "/root/ca/int_ca_bundle"
   "crl_chain": "/root/ca/int_crl_chain"
   "private_key": "/root/ca/int_key"
 }
}
```

Optional: Validate that the CA is working by running

puppet agent
                  -t

and verifying your intermediate CA with OpenSSL.

openssl x509 -in /etc/puppetlabs/puppet/ssl/ca/signed/<HOSTNAME>.crt 
-text -noout
Certificate:
   Data:
       Version: 3 (0x2)
       Serial Number: 1 (0x1)
   Signature Algorithm: sha256WithRSAEncryption
       Issuer: CN=intermediate-ca
...

Related information

Certificates installed