This Dockerfile's layer order makes every code edit cost a 122-second rebuild: COPY . . sits FIRST, so touching any source file busts the cache for everything after it — including the 120-second pip install whose inputs didn't change. Reorder the layers: requirements copy, then pip install, then the code copy last. A code change should rebuild in 1 second.
The break is on line 2 — but read the whole snippet first.