Python script to get list of installed packages that have upgrades and output in JSON

list-upgradable.py

#!/usr/bin/python3

# NOTE: Requires the python3-apt package

import apt
import apt_pkg
import json

need_upgrade = []

cache = apt.apt_pkg.Cache()
dep_cache = apt.apt_pkg.DepCache(cache)
for pkg in cache.packages:
     if dep_cache.is_upgradable(pkg) and pkg.current_state == apt_pkg.CURSTATE_INSTALLED:
             #print("  ", pkg.name)
             need_upgrade.append(pkg.name)
             print(pkg.name, " needs upgrade. Current version is: ", pkg.current_ver.ver_str, "\n latest is: ", \
                     dep_cache.get_candidate_ver(pkg).ver_str)

print(json.dumps(need_upgrade))