Extra script to make PlatformIO do compressed OTA updates for the ESP8266

compressed_ota.py

import gzip
import shutil
import os
Import("env")


def compressFirmware(source, target, env):
    """ Compress ESP8266 firmware using gzip for 'compressed OTA upload' """
    SOURCE_FILE = env.subst("$BUILD_DIR") + os.sep + env.subst("$PROGNAME") + ".bin"
    if not os.path.exists(SOURCE_FILE+'.bak'):
        print("Compressing firmware for upload...")
        shutil.move(SOURCE_FILE, SOURCE_FILE + '.bak')
        with open(SOURCE_FILE + '.bak', 'rb') as f_in:
            with gzip.open(SOURCE_FILE, 'wb') as f_out:
                shutil.copyfileobj(f_in, f_out)

    if os.path.exists(SOURCE_FILE+'.bak'):
        ORG_FIRMWARE_SIZE = os.stat(SOURCE_FILE + '.bak').st_size
        GZ_FIRMWARE_SIZE = os.stat(SOURCE_FILE).st_size

        print("Compression reduced firmware size to {:.0f}% of original (was {} bytes, now {} bytes)".format((GZ_FIRMWARE_SIZE / ORG_FIRMWARE_SIZE) * 100, ORG_FIRMWARE_SIZE, GZ_FIRMWARE_SIZE))

env.AddPreAction("upload", compressFirmware)

Thanks for showing how to get compressed OTA updates to work in PlatformIO! I made a fork with a couple changes to improve handling of incremental builds: (1) If the .bin file is newer than the .bak file, then go ahead and do the compression (assumes that .bin is freshly generated and not compressed), (2) After compressing, set the modification time of the compressed image to the same as the original so it doesn't break #1 and so incremental builds see the original timestamp.

No problem! And thanks for taking it further! :)

Thanks for the script, seems to work pretty well.

One thing worth changing though, on line 21 where it prints the % it should be 100 - (GZ_FIRMWARE_SIZE / ORG_FIRMWARE_SIZE) * 100, otherwise you're getting the final compressed % size, not the % size it was reduced by

lol... so it does... I obviously had a brain fart moment there, there, as that was the percentage I wanted to see, but the message should have been something like Compression reduced firmware size to {:.0f}% of original size. I see andrewwalters spotted that also when he made the other tweaks.

Thanks for the suggestion!

Thx for this script.

One suggested improvement:
SOURCE_FILE = source[0].get_abspath()

Then I prefer to use this as part of the build rather than upload. This is achieved by replacing last row with:
env.AddPostAction("buildprog", compressFirmware)