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50b986a265
refactor README.rst and architecture file into sphinx doc project, automatically deploying on main merges and PRs. * add FAQs from https://chatmail.at/relays landing page * fix links, and streamline postfix/dovecot mentioning * add linkcheck to CI, fix several links and streamlihne DKIM section while at it * some streamlining, rename to "overview" * ci: upload documentation to chatmail.at/doc/relay * ci: main should be uploaded when docs.yaml changes * ci: fix typo * Update .github/workflows/docs-preview.yaml Co-authored-by: missytake <missytake@systemli.org>
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2.6 KiB
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74 lines
2.6 KiB
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Migrating to a new host
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-----------------------
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If you want to migrate chatmail relay from an old machine to a new
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machine, you can use these steps. They were tested with a Linux laptop;
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you might need to adjust some of the steps to your environment.
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Let’s assume that your ``mail_domain`` is ``mail.example.org``, all
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involved machines run Debian 12, your old site’s IP address is
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``13.37.13.37``, and your new site’s IP address is ``13.12.23.42``.
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Note, you should lower the TTLs of your DNS records to a value such as
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300 (5 minutes) so the migration happens as smoothly as possible.
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During the guide you might get a warning about changed SSH Host keys; in
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this case, just run ``ssh-keygen -R "mail.example.org"`` as recommended.
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1. First, disable mail services on the old site.
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::
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cmdeploy run --disable-mail --ssh-host 13.37.13.37
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Now your users will notice the migration and will not be able to send
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or receive messages until the migration is completed.
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2. Now we want to copy ``/home/vmail``, ``/var/lib/acme``,
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``/etc/dkimkeys``, ``/run/echobot``, and ``/var/spool/postfix`` to
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the new site. Login to the old site while forwarding your SSH agent
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so you can copy directly from the old to the new site with your SSH
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key:
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::
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ssh -A root@13.37.13.37
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tar c - /home/vmail/mail /var/lib/acme /etc/dkimkeys /run/echobot /var/spool/postfix | ssh root@13.12.23.42 "tar x -C /"
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This transfers all addresses, the TLS certificate, DKIM keys (so DKIM
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DNS record remains valid), and the echobot’s password so it continues
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to function. It also preserves the Postfix mail spool so any messages
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pending delivery will still be delivered.
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3. Install chatmail on the new machine:
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::
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cmdeploy run --disable-mail --ssh-host 13.12.23.42
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Postfix and Dovecot are disabled for now; we will enable them later.
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We first need to make the new site fully operational.
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4. On the new site, run the following to ensure the ownership is correct
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in case UIDs/GIDs changed:
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::
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chown root: -R /var/lib/acme
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chown opendkim: -R /etc/dkimkeys
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chown vmail: -R /home/vmail/mail
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chown echobot: -R /run/echobot
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5. Now, update DNS entries.
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If other MTAs try to deliver messages to your chatmail domain they
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may fail intermittently, as DNS catches up with the new site settings
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but normally will retry delivering messages for at least a week, so
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messages will not be lost.
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6. Finally, you can execute ``cmdeploy run --ssh-host 13.12.23.42`` to
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turn on chatmail on the new relay. Your users will be able to use the
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chatmail relay as soon as the DNS changes have propagated. Voilà!
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