Sentry installations are grouped by “realms”, like our Jenkins installations.
Realm information is configurable in the new saas/ pillar entry.
The main wrapper script sentry allows to run command for any realm spawning
a new container and running sentry. It calls a local wrapper script with
correct links, and credentials information to run Docker container.
The standard image is configurable through environment. As such, there is no
current need to build a custom image.