How to: upload esp8266 firmware via Docker

[easytarget]

Currently the README for building the esp8266 firmware advises to use Docker for building the firmware itself, but then advises to run make deploy directly on the host to program the board.

On my Fedora40 box, the docker build went very well, but then deploy crashed out badly:

owen@sam:~/MPython/micropython/ports/esp8266$ make PORT=/dev/ttyUSB0 deploy
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
make: xtensa-lx106-elf-gcc: No such file or directory
make: xtensa-lx106-elf-gcc: No such file or directory
make: xtensa-lx106-elf-gcc: No such file or directory
CC ../../py/mpstate.c
/bin/sh: line 1: xtensa-lx106-elf-gcc: command not found
See https://github.com/micropython/micropython/wiki/Build-Troubleshooting
make: *** [../../py/mkrules.mk:90: build-ESP8266_GENERIC/py/mpstate.o] Error 1 

Eg; make deploy is now dependent on the ESP toolchain. Kind of defeating the purpose of using Docker in the first place.. But I wondered if Docker could do it via a device mapping.

Turns out to be trivial; the --device option in Docker plus giving the image permissions to use the device. The trick with permissions it to set the docker user GID to that of the device you are using. eg:

owen@sam:~$ ls -l /dev/ttyUSB0
crw-rw----. 1 root dialout 188, 0 Jul 12 10:46 /dev/ttyUSB0

As expected, the serial device is owned by root but has dialout as it's group, simply seetting that as the docker users GID, along with the device mapping, works well:

owen@sam:~/MPython/micropython/ports/esp8266$ docker run --rm -v $HOME:$HOME -u $UID:dialout -w $PWD --device=/dev/ttyUSB0 larsks/esp-open-sdk make PORT=/dev/ttyUSB0 deploy

Note the addition of :dialout to the -u option to set the GID as well as UID, and the addition of --device to ensure that /dev/USB0 is accessible to the container. Since I am using /dev/ttyUSB0 and not the default device (/dev/ttyACM0) I also pass that to the make command.

This works, the board then programs perfectly :-)

..snip..
Verifying just-written flash...
Verifying 0xdc738 (902968) bytes @ 0x00000000 in flash against build-ESP8266_GENERIC/firmware.bin...
-- verify OK (digest matched)

I plan to put in a PR against ports/esp8266/README.md for this, unless anybody has thoughts/doubts/comments?

[easytarget]

Possibly in the wrong category; not really a question.