Clean up Dockerfile

Dockerfile

@@ -6,8 +6,9 @@ RUN : \
  && apt-get autoremove -y \
  && rm -rf /var/lib/apt/lists/*
 RUN git clone --depth 1 -b v1.17 https://github.com/micropython/micropython.git /src
-RUN cd /src/mpy-cross && make
-RUN cd /src/ports/unix && make submodules && make
-RUN cd /src/ports/esp32 && bash -c "source /opt/esp/idf/export.sh && make"
+WORKDIR /src
+RUN make -C mpy-cross
+WORKDIR /src/ports/esp32
+RUN bash -c "source /opt/esp/idf/export.sh && make submodules && make"
 RUN rm /src/ports/esp32/build-GENERIC/frozen_content.c
-CMD /src/ports/unix/micropython
+CMD make && cp build-GENERIC/firmware.bin /build/

README.md

@@ -0,0 +1,13 @@
+This Docker image drastically simplifies building MicroPython binaries for ESP32 microcontrollers with
+[frozen modules](https://docs.micropython.org/en/latest/reference/manifest.html#freezing-source-code)
+-- that is flashable MicroPython images that include your payload as bytecode so they're easy to deploy.
+
+Place your source code under `modules/` and the Docker image should pick them
+up and bundle them into the resulting firmware image placed under `build/`
+
+```
+docker run --rm -v $PWD/modules:/src/ports/esp32/modules -v $PWD/build:/build harbor.k-space.ee/k-space/micropython-esp32
+esptool.py -p /dev/ttyUSB0 --chip esp32 -b 460800 write_flash -z 0x1000 build/firmware.bin
+```
+
+Currently stuck with MicroPytyhon 1.17 until [this](https://github.com/micropython/micropython/issues/8410) fix is included with 1.19+.