Changing a CA SSL certificate for the Agent Bakery

Owned by Anastasios Thomaidis
Last updated: Jan 19, 2024 by Matthew Hierholzer
1 min read
If your Checkmk Server is using HTTPS, and you're using the Agent Bakery, your SSL Certificate will expire at some time. If the CA for the new certificate stays the same, this should be no problem for the Agent Bakery. However, if the CA changes, or if you change a single certificate, you must follow some extra steps.

LAST TESTED ON CHECKMK 2.2.0P1

Table of Contents


Getting Started

Background information regarding this subject is available on our:

Step-by-step guide

  1. Get new certificate

  2. Check if the certificate chain has changed. If:

    • Yes: Jump to step 3
    • No: Jump to step 4


  3. The chain or a single certificate has changed
     
    1. Add the new chain to the Agent Updater (do NOT replace the old chain!). 

    2. Bake and sign agents

    3. Wait until all agents updated

    4. Jump to step 4


  4. The chain did not change, or step 3 was done

    1. Restrict Auto Updates to only 2 or 3 hosts, so if something goes wrong, you do not mess up everything

    2. Deploy the new certificate to the Apache server

      For Checkmk Appliances: Click on Device Settings → Web Access → Upload Certificate

      screenshot showing the location of device settings

      screenshot showing the location of web access

      screenshot showing the location of upload certifcate

      For more information about Appliances and SSL certificates, please refer to our Official Documentation.

      .

    3. Check for the correct cert and chain by using a browser

    4. Make sure Auto Update works for the test hosts

    5. If the chain changed (see step 3), remove the old chain from the updater rule, bake & sign agents, and see if everything works with the test hosts

    6. Remove the restriction to the test hosts and update all agents