Make it possible to exclude packages by name

In some situations some packages may need to be excluded, e.g. if we're
expecting some odd situation. In this case it would be nice to exclude
the packages by name.

Signed-off-by: Gabriel Filion <lelutin@torproject.org>

Author: Gabriel Filion

apt_info.py

@@ -24,6 +24,7 @@
 
 import apt
 import apt_pkg
+import argparse
 import collections
 import logging
 import os
@@ -60,9 +61,11 @@ def _convert_candidates_to_upgrade_infos(candidates):
     return changes_list
 
 
-def _write_pending_upgrades(registry, cache):
+def _write_pending_upgrades(registry, cache, exclusions):
     candidates = {
-        p.candidate for p in cache if p.is_upgradable and not p.phasing_applied
+        p.candidate
+        for p in cache
+        if p.is_upgradable and not p.phasing_applied and p.name not in exclusions
     }
     for candidate in candidates:
         logging.debug(
@@ -79,13 +82,14 @@ def _write_pending_upgrades(registry, cache):
             g.labels(change.labels['origin'], change.labels['arch']).set(change.count)
 
 
-def _write_held_upgrades(registry, cache):
+def _write_held_upgrades(registry, cache, exclusions):
     held_candidates = {
         p.candidate for p in cache
         if (
             p.is_upgradable
             and p._pkg.selected_state == apt_pkg.SELSTATE_HOLD
             and not p.phasing_applied
+            and p.name not in exclusions
         )
     }
     for candidate in held_candidates:
@@ -103,13 +107,14 @@ def _write_held_upgrades(registry, cache):
             g.labels(change.labels['origin'], change.labels['arch']).set(change.count)
 
 
-def _write_obsolete_packages(registry, cache):
+def _write_obsolete_packages(registry, cache, exclusions):
     # This corresponds to the apt filter "?obsolete"
     obsoletes = [p for p in cache if p.is_installed and (
                   p.candidate is None or
                   not p.candidate.origins or
                   (len(p.candidate.origins) == 1 and
                    p.candidate.origins[0].origin in ['', "/var/lib/dpkg/status"])
+                  and p.name not in exclusions
                 )]
     for package in obsoletes:
         if package.candidate is None:
@@ -126,9 +131,11 @@ def _write_obsolete_packages(registry, cache):
     g.set(len(obsoletes))
 
 
-def _write_autoremove_pending(registry, cache):
+def _write_autoremove_pending(registry, cache, exclusions):
     autoremovable_packages = {
-        p.candidate for p in cache if p.is_auto_removable
+        p.candidate
+        for p in cache
+        if p.is_auto_removable and p.name not in exclusions
     }
     for candidate in autoremovable_packages:
         logging.debug(
@@ -181,13 +188,17 @@ def _main():
     if os.getenv('DEBUG'):
         logging.basicConfig(level=logging.DEBUG)
 
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--exclude", nargs='*', default=[])
+    args = parser.parse_args(sys.argv[1:])
+
     cache = apt.cache.Cache()
 
     registry = CollectorRegistry()
-    _write_pending_upgrades(registry, cache)
-    _write_held_upgrades(registry, cache)
-    _write_obsolete_packages(registry, cache)
-    _write_autoremove_pending(registry, cache)
+    _write_pending_upgrades(registry, cache, args.exclude)
+    _write_held_upgrades(registry, cache, args.exclude)
+    _write_obsolete_packages(registry, cache, args.exclude)
+    _write_autoremove_pending(registry, cache, args.exclude)
     _write_installed_packages_per_origin(registry, cache)
     _write_cache_timestamps(registry)
     _write_reboot_required(registry)