When the Puppet agent software runs for the first time on any Puppet node, it generates a certificate and sends the certificate signing request to the Puppet master. Before the Puppet server is able to communicate and control the agent nodes, it must sign that particular agent node’s certificate. In the following sections, we will describe how to sign and check for the signing request.

List Current Certificate Requests

On the Puppet master, run the following command to see all unsigned certificate requests.

$ sudo /opt/puppetlabs/bin/puppet cert list

As we have just set up a new agent node, we will see one request for approval. Following will be the output.

"Brcleprod004.brcl.com" (SHA259) 
15:90:C2:FB:ED:69:A4:F7:B1:87:0B:BF:F7:ll:
B5:1C:33:F7:76:67:F3:F6:45:AE:07:4B:F 6:E3:ss:04:11:8d 

It does not contain any + (sign) in the beginning, which indicates that the certificate is still not signed.

Sign a Request

In order to sign the new certificate request which was generated when the Puppet agent run took place on the new node, the Puppet cert sign command would be used, with the host name of the certificate, which was generated by the newly configured node that needs to be signed. As we have Brcleprod004.brcl.com’s certificate, we will use the following command.

$ sudo /opt/puppetlabs/bin/puppet cert sign Brcleprod004.brcl.com 

Following will be the output.

Notice: Signed certificate request for Brcle004.brcl.com 
Notice: Removing file Puppet::SSL::CertificateRequest Brcle004.brcl.com at 
''/etc/puppetlabs/puppet/ssl/ca/requests/Brcle004.brcl.com.pem'' 

The puppet sever can now communicate to the node, where the sign certificate belongs.

$ sudo /opt/puppetlabs/bin/puppet cert sign --all 

Revoking the Host from the Puppet Setup

There are conditions on configuration of kernel rebuild when it needs to removing the host from the setup and adding it again. These are those conditions which cannot be managed by the Puppet itself. It could be done using the following command.

$ sudo /opt/puppetlabs/bin/puppet cert clean hostname 

Viewing All Signed Requests

The following command will generate a list of signed certificates with + (sign) which indicates that the request is approved.

$ sudo /opt/puppetlabs/bin/puppet cert list --all

Following will be its output.

+ "puppet" (SHA256) 5A:71:E6:06:D8:0F:44:4D:70:F0:
BE:51:72:15:97:68:D9:67:16:41:B0:38:9A:F2:B2:6C:B 
B:33:7E:0F:D4:53 (alt names: "DNS:puppet", "DNS:Brcle004.nyc3.example.com")  

+ "Brcle004.brcl.com" (SHA259) F5:DC:68:24:63:E6:F1:9E:C5:FE:F5:
1A:90:93:DF:19:F2:28:8B:D7:BD:D2:6A:83:07:BA:F E:24:11:24:54:6A 

+ " Brcle004.brcl.com" (SHA259) CB:CB:CA:48:E0:DF:06:6A:7D:75:E6:CB:22:BE:35:5A:9A:B3 

Once the above is done, we have our infrastructure ready in which the Puppet master is now capable of managing newly added nodes.