Fuck buildx cache

fuckcache.py

#!/usr/bin/env python3

'''
Usage: ./fuckcache.py \
  --mount=type=secret,id=npmrc,target=/root/.npmrc \
  --mount=type=cache,target=/root/.npm \
  --mount=type=cache,id=somecache,target=/var/cache/somecache
like docker RUN instruction

it will product dockerfile and build it
'''

import os
import sys
import re
import tempfile
import subprocess

argRe = re.compile(r"^--mount=([^,]+)(,[^,]+)*$")

caches = []

for argStr in sys.argv[1:]:
    match = argRe.match(argStr)
    if not match:
        print("not recognized", argStr)
        continue
    arg = {}
    for part in match.groups():
        k, v = part.lstrip(",").split("=", maxsplit=1)
        arg[k] = v

    if arg["type"] != "cache":
        print("not cache", argStr)
        continue

    arg["raw"] = argStr

    caches.append(arg)

# make Dockerfile
tempdir = tempfile.mkdtemp()
print("tempdir", tempdir)
dockerfile = os.path.join(tempdir, "Dockerfile")


with open(dockerfile, "w") as f:
    f.write("FROM alpine\n")

    f.write("RUN \\\n")
    for cache in caches:
        f.write(f"    {cache['raw']} \\\n")

    f.write(f"    set -x ; \\\n")

    # re-order caches to delete recursive
    for cache in sorted(caches, key=lambda x: len(x["target"]), reverse=True):
        f.write(f"    rm -rf {cache['target']}/* {cache['target']}/.* ; \\\n")

    # make build failed
    f.write(f"    echo done; false\n")

# subprocess.run(["cat", f"{tempdir}/Dockerfile"])
subprocess.run(["docker", "buildx", "build", tempdir, "--force-rm", "--progress=plain"])