Adding the CMD from @edasque in once more as it allows specifying more than one board via host ENV vars. Currently, the Dockerfile is hard-coded.
@@ -25,4 +25,4 @@ ENV keymap=default
VOLUME /qmk
WORKDIR /qmk
-CMD make clean; make;
+CMD make clean ; make keyboard=${keyboard} subproject=${subproject} keymap=${keymap}