The file that was there yesterday
Uploads are written to a directory inside the container and served back from the same place. It worked on one instance, and it worked for a year on the virtual machine before that.
There are four replicas now. An upload lands on one of them, the next request is balanced to another and 404s, and every deploy replaces all four and takes the files with them.
Boundaries, outermost first: Replaced on deploy: Replica A (has the file), Replica C (returns 404), Replica B (returns 404; FAILED: cannot see it) Outside every boundary: Load balancer, Uploads, an empty slot for the outlives the container Connections: Uploads calls Load balancer (step 1) Load balancer calls Replica A (step 2) Replica A calls outlives the container — write (step 3) Replica B calls outlives the container — read Replica C calls outlives the container