Where docker lives is device-specific; what to do with it is not. QNAP's
Container Station installs docker under /share/<pool>/.qpkg/ and never
puts it on PATH, so a QTS driver inheriting this class found no docker at
all.
Rather than reimplementing the Docker surface in the vendor driver, the
path becomes a single overridable method and every call site goes through
it. Per docs/ARCHITECTURE.md 4.4, generic logic belongs to the shared
driver and only the device-specific mechanics belong to the vendor one.
A test asserts that *every* docker call site uses the hook — a half
converted set would let detection find the binary while the actual
queries still missed it, which only shows up against real hardware.
christianmanivong
c8fc46c373