Code to check OS package in Python

check_os_package.py

import re
import shutil
import subprocess

rootfs_packages = {
    'jupyter': '4.4',
    'python3-opencv': '3.2.0',
    'lm-sensors': '1'
}

# Convert version number
def convert_version(version):
    while version.count('.') < 2:
        version += '.0'
    version_temp = [int(x, 10) for x in version.split('.')]
    version_temp.reverse()
    return sum(x * (100 ** i) for i, x in enumerate(version_temp))


# Check available command for packaging tool
def get_package_tool():
    for i in ['apt', 'rpm']:
        if shutil.which(i) is not None:
            return i
    return None


# For apt tool
def find_apt_package(package_name):
    command = 'apt-cache show {} | grep Version'.format(package_name)
    output = subprocess.Popen(command, shell=True,
                              stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    ret = output.communicate()[0].decode("utf-8")
    version_match = re.search(r"^Version: ([0-9\.]*)", ret, re.M)
    return version_match


# For rpm tool
def find_rpm_package(package_name):
    command = 'rpm -qa | grep {}'.format(package_name)
    output = subprocess.Popen(command, shell=True,
                              stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    ret = output.communicate()[0].decode("utf-8")
    version_match = re.search(r"^{}-([0-9\.]*)-*".format(package_name),
                              ret, re.M)
    return version_match

# Check minimum version. If the package is bootstrapped, we can ignore this
def check_min_package(package_name):
    min_version = rootfs_packages[package_name]
    pkg_tool = get_package_tool()
    if pkg_tool == 'apt':
        version_match = find_apt_package(package_name)
    elif pkg_tool == 'rpm':
        version_match = find_apt_package(package_name)
    else:
        raise EnvironmentError("Linux flavor is not supported.")

    if version_match:
        found_version = convert_version(version_match.group(1))
    else:
        raise EnvironmentError("Package {0} is missing. Use {1} to "
                               "install it".format(package_name, pkg_tool))
    if found_version < convert_version(min_version):
        raise EnvironmentError("Minimum required version for {0} is "
                               "{1}".format(package_name, min_version))

check_min_package('lm-sensors')
check_min_package('jupyter')
check_min_package('python3-opencv')