Switch to a per-namespace configurable expiration policy for time machine, and switch the tag gc to respect it.

data/database.py

@@ -1,12 +1,14 @@
 import string
 import logging
 import uuid
+import time
 
 from random import SystemRandom
 from datetime import datetime
 from peewee import *
-from data.read_slave import ReadSlaveModel
 from sqlalchemy.engine.url import make_url
+
+from data.read_slave import ReadSlaveModel
 from util.names import urn_generator
 
 
@@ -136,6 +138,9 @@ def uuid_generator():
   return str(uuid.uuid4())
 
 
+_get_epoch_timestamp = lambda: int(time.time())
+
+
 def close_db_filter(_):
   if not db.is_closed():
     logger.debug('Disconnecting from database.')
@@ -175,6 +180,7 @@ class User(BaseModel):
   invoice_email = BooleanField(default=False)
   invalid_login_attempts = IntegerField(default=0)
   last_invalid_login = DateTimeField(default=datetime.utcnow)
+  removed_tag_expiration_s = IntegerField(default=1209600)  # Two weeks
 
   def delete_instance(self, recursive=False, delete_nullable=False):
     # If we are deleting a robot account, only execute the subset of queries necessary.
@@ -456,8 +462,8 @@ class RepositoryTag(BaseModel):
   name = CharField()
   image = ForeignKeyField(Image)
   repository = ForeignKeyField(Repository)
-  lifetime_start = DateTimeField(default=datetime.utcnow)
-  lifetime_end = DateTimeField(null=True)
+  lifetime_start_ts = IntegerField(default=_get_epoch_timestamp)
+  lifetime_end_ts = IntegerField(null=True, index=True)
 
   class Meta:
     database = db