webapps are meant to be build-once/deploy-many, but we were rebuilding them for every request. This changes that, so that we rebuild only for every unique ApplicationRecord.
When we push the image, we now tag it according to its ApplicationRecord.
We don't want to use that tag directly in the compose file for the deployment, however, as the deployment needs to be able to adjust to new builds w/o re-writing the file all the time. Instead, we use a per-deployment unique tag (same as before), we just update what image it references as needed.
Reviewed-on: cerc-io/stack-orchestrator#764
telackey
dboreham
