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- We have our existing group service (call it 'gws2') that uses Grouper 2.1 as a backend.
- Create a new group service (call it 'gws23') that uses Grouper 2.3 as a backend. This was first deployed on a separate host, but finally deployed on the production application hosts in a rolling upgrade.
- Set up an AWS FIFO message queue ('aws12') for sending updates from gws2 to gws23
- Set up an AWS FIFO message queue ('aws21') for sending updates from gws23 to gws2. This part allows us to roll back the migration.
- Start the aws12 sender. This will save all updates in the WAS queue. Lifetime there is 4 days. Should be more than enough.
- Dump the gws2 database and load it into gws23.
- Run the conversion scripts and the bad membership remover. This took a couple of days. It could have been one very long day, but I wanted to watch some of it run and also sleep at night.
- Run the aws12 receiver to bring the gws23 database up to date with gws2. At this point there were a little over 3000 messages in the queue.
- Start the aws21 receiver to copy updates on the new system to the old.
- Switch two of the four application hosts to the new database (gws23) and switch DNS from the old to the new. This puts users on the new service, while keeping the old service up-to-date in case of any need to roll back.
- Upgrade the other two hosts.
- At this point users are on the new service with the upgraded database and never lost so much as a connection.
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