Question: How to merge 2 servers into 1?

[CapSel]

Subject

I would like to configure a not documented mail server use case

Description

This is not a bug, or security issue - just question... or help request.

So I have 2 servers in OVH. Both servers have similar configuration. One of the servers needs to be decommissioned because OVH wants to eliminate one of data centres. Amount of e-mails and traffic allows me to merge them into one but...

So each of the servers have:

• domain name = host name // aka top level domain, configured in compose yaml
• DKIM, SPF, MX in name zone
• certificate from let's encrypt - no automation here
• there are other services on subdomains

I can have downtime of one weekend.

I was thinking about just "merging" config (add lines to file already existing) and data directories.

Problems that I can see:

• how to merge DKIM configuration and key?
• can I just rsync let's encrypt config from one server to another? there is a nginx and some domains so maybe it would be simpler to move domain to second server, create empty web page, and generate certificate there?
• I don't think I'll be able to move all services from old server in one weekend - so I can't redirect all subdomains

How should I approach it?

[glime-ai]

Please note that this response was created using generative AI, leveraging previously available information from the repository. This information may be helpful. However, it is our strong recommendation that you carefully consider the information before blindly applying it.

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To merge your two Docker Mail Server (DMS) setups into one, you'll need to carefully plan and execute the migration of configurations, data, and services. Here are the steps and considerations for each of your concerns:

1. Merging DKIM Configuration and Keys:

   • Each domain should have its own DKIM key. If you're using the same DMS instance for both domains, you'll need to ensure that each domain's DKIM key is correctly configured.
   • Use the docker exec -it <CONTAINER NAME> setup config dkim domain <DOMAIN> command for each domain to generate or reconfigure DKIM keys as needed.
   • Update your DNS records for each domain to include the correct DKIM TXT records.

2. Merging Let's Encrypt Certificates:

   • It's possible to rsync the Let's Encrypt configuration and certificates, but this might lead to complications due to differences in server configurations or potential conflicts.
   • A safer approach would be to reissue the certificates on the new server. You can do this by setting up a minimal web server configuration for the domain verification process, then using certbot or a similar tool to generate new certificates.

3. Handling Services and Subdomains:

   • If you cannot move all services from the old server in one weekend, consider using a reverse proxy (like nginx or Traefik) on the new server to temporarily redirect traffic for specific subdomains back to the old server.
   • Gradually migrate services to the new server as you verify their functionality.

4. General Migration Steps:

   • Backup all configurations and data from both servers.
   • Start by setting up the primary domain on the new server, including mail services and DNS configurations.
   • Incrementally add the configurations from the second server, testing each step to ensure stability.
   • Update DNS records to point to the new server once you're confident in the stability of the services.

5. Testing and Validation:

   • After each change, thoroughly test the configuration to ensure that mail delivery, DKIM signing, and SSL/TLS certificates are functioning correctly.
   • Monitor the logs for any errors or warnings that could indicate misconfigurations.

By following these steps, you should be able to consolidate your mail servers with minimal downtime and disruption.

This comment was generated by Glime.

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