sysadmin/puppet: Add a puppet agent certificate renewal section

sysadm/puppet/howto-renew-agent-certificate.rst

+.. _puppet_howto_renew_agent_certificate:
+
+How to renew an agent certificate
+=================================
+
+.. admonition:: Intended audience
+   :class: important
+
+   sysadm members
+
+
+Check the certificate expiration dates
+--------------------------------------
+
+On the puppet master (pergamon):
+
+::
+
+  root@pergamon:~# cd /var/lib/puppet/ssl/ca/signed
+  root@pergamon:/var/lib/puppet/ssl/ca/signed# openssl x509 -text -in worker01.softwareheritage.org.pem | grep -i 'not after'
+          Not After : Oct 29 18:37:49 2022 GMT
+
+Check the certificate statuses
+------------------------------
+
+On the puppet master (pergamon):
+
+::
+
+  root@pergamon:~# puppet cert --list --all
+  Warning: `puppet cert` is deprecated and will be removed in a future release.
+    (location: /usr/lib/ruby/vendor_ruby/puppet/application.rb:370:in `run')
+  ...
+  + "worker3.internal.staging.swh.network"                          (SHA256) A5:0C:46:21:C9:C6:B2:...:10:D3:C4:24:90:55:1D:56
+  - "beaubourg.softwareheritage.org"                                (SHA256) 24:50:2E:7F:8B:B0:C7:...:D9:AB:5A:45:46:4D:17:51 (certificate has expired)
+  ...
+
+worker3 certificate is ok, beaubourg certificate is expired
+
+Renew an agent certificate
+--------------------------
+
+On the puppet master (pergamon):
+
+- Revoke and delete the old certificate
+
+::
+
+  root@pergamon:~# puppet cert clean beaubourg.softwareheritage.org
+  Warning: `puppet cert` is deprecated and will be removed in a future release.
+    (location: /usr/lib/ruby/vendor_ruby/puppet/application.rb:370:in `run')
+  Notice: Revoked certificate with serial 49
+  Notice: Removing file Puppet::SSL::Certificate beaubourg.softwareheritage.org at '/var/lib/puppet/ssl/ca/signed/beaubourg.softwareheritage.org.pem'
+  Notice: Removing file Puppet::SSL::Certificate beaubourg.softwareheritage.org at '/var/lib/puppet/ssl/certs/beaubourg.softwareheritage.org.pem'
+
+On the agent (beaubourg for this example), delete the old certificate and generate a new one:
+
+::
+
+  root@beaubourg:~# rm -r /var/lib/puppet/ssl
+  root@beaubourg:/var/lib/puppet# puppet agent --test
+  Info: Creating a new SSL key for beaubourg.softwareheritage.org
+  Info: Caching certificate for ca
+  Info: csr_attributes file loading from /etc/puppet/csr_attributes.yaml
+  Info: Creating a new SSL certificate request for beaubourg.softwareheritage.org
+  Info: Certificate Request fingerprint (SHA256): F5:C9:99:0B:...:62:E9:4F:1B
+  Info: Caching certificate for beaubourg.softwareheritage.org
+  Info: Caching certificate_revocation_list for ca
+  Info: Caching certificate for ca
+  Info: Using configured environment 'production'
+  Info: Retrieving pluginfacts
+  Info: Retrieving plugin
+  Info: Retrieving locales
+  Info: Loading facts
+  Info: Caching catalog for beaubourg.softwareheritage.org
+  Info: Applying configuration version '1638980028'
+  ...

sysadm/puppet/index.rst

@@ -9,5 +9,6 @@ Puppet
    howto-manage-third-party-modules
    howto-test-changes-in-vagrant
    howto-deploy-puppet-change
+   howto-renew-agent-certificate
    reference-architecture
    reference-best-practices