Some thoughts on best practices for debian.org services:

use packages from stable/backports
use packages rather than embedded code copies
add a metapackage to debian.org.git
have multiple maintainers
user-facing services should have multiple frontends
public version control
links to bug reporting, code, sponsors in footers
minimise use of shell/php
don't use unsafe language contructs (os.system yaml.load etc)
have the code audited
use SSL cert pinning
architecture independent
refresh suite/arch/repo/etc info from repos/etc
have documentation
use sso.d.o or keys for authentication
be subscribed to the debian-services-admin list

More:

https://wiki.debian.org/ServicesHosting