[katello-devel] Katello upgrade redesign

[Bryan Kearney]

On 10/26/2012 06:05 AM, Lukas Zapletal wrote:
> Hello,
>
> working on https://bugzilla.redhat.com/show_bug.cgi?id=868916 , I found we
> have some bugs and also design issues with katello upgrade.
>
> The current design is simple, we have two kinds of upgrade scripts which
> are in two directories.
>
> /usr/share/katello/install/upgrade-scripts/default/*
>
> and
>
> /usr/share/katello/install/upgrade-scripts/upgrade/*
>
> Katello-upgrade first shuts downs all the services and then starts
> upgrading by calling upgrade scripts in this order: default, upgrade.
> Default scripts are executed every katello-upgrade call, while upgrade
> scripts are only executed once (and then katello-upgrade "marks" them in
> the /var/lib/katello/upgrade-history file (just a list of files which
> have been already executed).
>
> Default scripts (executed every time) are:
>
> 0002_update_pulp.sh
>   - starts mongod
>   - does pulp-migrate
> 0003_update_candlepin.sh
>   - executes dpdb
> 0004_migrate_katello_db.s
>   - starts candlepin and elasticsearch
>   - runs katello migration
>
> Upgrade scripts (executed only once) are:
>
> (none for CFSE 1.0/1.1 - just two examples that does nothing)
>
> 0001_preallocate_mongo.sh
>   - prepares mongo journal for new version of mongo
> 0002_create_foreman_user
>   - creates foreman user
>
> Now there are couple of issues which are blockers for CFSE 1.1 and
> couple of design issues I would like to also fix for Katello.
>
> Basically katello-upgrade currently does not work in CFSE 1.1 because we
> have some code logic in the migration scripts (filters) which require
> all the backend engines to be running. We are not starting pulp and also
> elasticsearch starts slowly and we need to wait until it is available.
>
> Also there are couple of example migration scripts which does nothing,
> but creating pyc/pyo bytecode files which are then added to the executed
> list. I will remove them and make sure python scripts does not create
> those.
>
> That is necessary for CFSE 1.1 upgrades, now for Katello we have a
> design issue. Some scripts need the services to be running (like
> pulp migration), others must not have services running (candlepin
> migration).
>
> Therefore for Katello, I plan to split our upgrade scripts into two
> categories (by script numbers):
>
> 0001-2999: Will be executed when backend engines are down
> 3000-5999: Will be executed when backend engines are up
> 6000-9999: Will be executed when backend engines and Katello are up
>
> This will be the same for both default and upgrade scripts. It would
> look (default scripts) like:
>
> 0001_stop_all_services
> 0010_migrate_candlepin
> 3000_start_backend_engines
> 3010_migrate_pulp
> 3020_migrate_katello
> 6000_start_katello

I dont know if it matters.. but should we just do different directories, 
instead of using magic numbers?

-- bk