Requirements.txt manager

reqman

#!/usr/bin/env python

import subprocess
import sys
import argparse
import warnings
import re
from pkg_resources import get_distribution, parse_version, DistributionNotFound


def get_env_version(pkg):
    try:
        return get_distribution(pkg).version
    except (ImportError, DistributionNotFound, ValueError):
        return None
    return None


def update_req(args):
    reqfn = args.req_file
    req = []
    changes = 0
    with open(reqfn, "rt") as f:
        for line in f:
            line = line.strip()
            prev_changes = changes
            if not line.startswith("#"):
                toks1 = re.split(";", line)
                toks2 = re.split("[=><]+", toks1[0].strip())
                if len(toks2) == 2:
                    pkg, ver = toks2
                    latest = get_env_version(pkg)
                    if latest is None:
                        print("Unable to determine environment version for %s. Using existing version." % (pkg))
                        latest = ver
                    if parse_version(latest) > parse_version(ver):
                        print("%s: %s -> %s" % (pkg, ver, latest))
                        changes += 1
                        if len(toks1) == 2:
                            req.append("%s==%s; %s" % (pkg, latest, toks1[-1].strip()))
                        else:
                            req.append("%s==%s" % (pkg, latest))
            if changes == prev_changes:
                req.append(line)
    if changes > 0:
        r = args.inplace or input("Write changes to %s (y/[n])? " % reqfn) == "y"
        if r:
            with open(reqfn, "wt") as f:
                f.write("\n".join(req))
    else:
        print("No changes needed!")


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="reqman is a manager for requirements.txt files",
        epilog="Author: Shyue Ping Ong")

    subparsers = parser.add_subparsers()

    parser_update = subparsers.add_parser(
        "update",
        help="Update requirements.txt based on current environment (detected using pkg_resources).")
    parser_update.add_argument("-i", "--inplace", dest="inplace",
                               action="store_true",
                               help="If set, the file will automatically be updated.")
    parser_update.add_argument("-r", "--req_file", dest="req_file",
                               default="requirements.txt",
                               help="Input requirements file. Defaults to requirements.txt in current directory.")
    parser_update.set_defaults(func=update_req)

    args = parser.parse_args()

    try:
        getattr(args, "func")
    except AttributeError:
        parser.print_help()
        sys.exit(0)
    args.func(args)