Version pinning for docker-compose

dhashes

#!/usr/bin/env python3

import json
import os
import subprocess
import sys

import yaml

if len(sys.argv) <= 1:
    print(
        """
Run this script in your docker project folder (where
docker-compose.yml resides)

Possible flags:

Update hashes based on local Docker inventory. docker-compose.yml
and related Dockerfiles will be written to.
-u, --update

Strip (get rid of any hashes in docker-compose.yml and Dockerfiles)
-s, --strip

Update local Docker image inventory (similar to pull, but also pulls
images referenced in context Dockerfiles)
-p, --pull

To update all image hashes, run dhashes -p && dhashes -u
"""
    )
    exit()

pull = False
strip = False

if len(sys.argv) > 1 and (sys.argv[1] == "--pull" or sys.argv[1] == "-p"):
    pull = True

if len(sys.argv) > 1 and (sys.argv[1] == "--strip" or sys.argv[1] == "-s"):
    strip = True


def get_new_image(image):
    image = image.split("@")[0]
    if strip or pull:
        return image
    else:
        inspection = json.loads(
            subprocess.run(
                ["docker", "inspect", image],
                stdout=subprocess.PIPE,
                stderr=subprocess.DEVNULL,
            ).stdout
        )
        if not inspection:
            raise RuntimeError("Run pull first, not all images are present locally")
        return image + "@" + inspection[0]["RepoDigests"][0].split("@")[1]


encountered_stripped_images = []

for dc_file in filter(lambda p: p.startswith("docker-compose"), os.listdir()):
    with open(dc_file, "r") as f:
        yaml_str = f.read()
        doc = yaml.safe_load(yaml_str)

    yaml_replacements = []
    for obj in doc["services"].values():
        if "build" in obj:
            with open(obj["build"]["context"] + "/Dockerfile", "r") as df:
                targets = []
                new_lines = []
                for line in df.read().split("\n"):
                    new_lines.append(line)

                    if line.startswith("FROM"):
                        split = line.split(" ")
                        if len(split) == 4:
                            targets.append(split[3].strip())
                        if split[1] not in targets:
                            encountered_stripped_images.append(
                                split[1].split("@")[0].strip()
                            )
                            split[1] = get_new_image(split[1])
                            new_lines[-1] = " ".join(split)

            if not pull:
                with open(obj["build"]["context"] + "/Dockerfile", "w") as df:
                    df.write("\n".join(new_lines))

        elif "image" in obj:
            encountered_stripped_images.append(obj["image"].split("@")[0])
            yaml_str = yaml_str.replace(
                "image: " + obj["image"] + "\n",
                "image: " + get_new_image(obj["image"]) + "\n",
            )

    if not pull:
        with open(dc_file, "w") as f:
            f.write(yaml_str)
    else:
        for stripped_image in set(encountered_stripped_images):
            print("Pulling ", stripped_image)
            subprocess.run(["docker", "pull", stripped_image])

    break
else:
    print("No docker-compose file found")