Based on https://wikitech.wikimedia.org/wiki/Switch_Datacenter#Manual_switch and https://wikitech.wikimedia.org/wiki/People.wikimedia.org#How_to_perform_a_switch-over_between_data_centers:
[x] find `rsync_src_host` and `rsync_dest_host` in [/hieradata/role/common/microsites/peopleweb.yaml](https://gerrit.wikimedia.org/r/plugins/gitiles/operations/puppet/+/refs/heads/production/hieradata/role/common/microsites/peopleweb.yaml#10)
[x] SSH to `dst_host` (you should see a warning in motd) and run manual rsync command:
[x] `rsync -avp rsync://people1004.eqiad.wmnet:/people-home /home/`
[x] Run puppet on `dst_host`
[x] In puppet hieradata the `rsync_src_host` and `rsync_dest_host` hosts need to be flipped: https://gerrit.wikimedia.org/r/959690
[x] merge and deploy change to both people machines
[x] check motd on both servers (should be swapped)
[x] The DNS discovery name `peopleweb.discovery.wmnet` needs to be switched from one backend to another: https://gerrit.wikimedia.org/r/959693
[x] merge and deploy DNS change
[x] confirm new backend gets traffic (`tail -f /var/log/apache2/*.log`).
[ ] Inform the users via a mailing list like "sre-at-large" (since that should cover shell users) that we switched and