Comment 2 for bug 1784074

I added an updated version of the script that checks if build requests exist which should make it a tad more user friendly, and fix cell_id

================================================================================
#!/usr/bin/env python

import urlparse

import pymysql

# Connect to databases
api_conn = pymysql.connect(host='xxxxxx', port=3306, user='nova_api', passwd='xxxx', db='nova_api')
api_cur = api_conn.cursor()

def _get_conn(db):
  parsed_url = urlparse.urlparse(db)
  conn = pymysql.connect(host=parsed_url.hostname, user=parsed_url.username, passwd=parsed_url.password, db=parsed_url.path[1:])
  return conn.cursor()

# Get list of all cells
api_cur.execute("SELECT id, name, database_connection FROM cell_mappings")
CELLS = [{'id': id, 'name': name, 'db': _get_conn(db)} for id, name, db in api_cur.fetchall()]

# Get list of all unmapped instances
api_cur.execute("SELECT instance_uuid FROM instance_mappings WHERE cell_id IS NULL")
print "Number of unmapped instances: %s" % api_cur.rowcount

# Go over all unmapped instances
unmapped_instances = api_cur.fetchall()
for (instance_uuid,) in unmapped_instances:
  instance_cell = None

  # Check if a build request exists, if so, skip.
  api_cur.execute("SELECT id FROM build_requests WHERE instance_uuid = %s", (instance_uuid,))
  if api_cur.rowcount != 0:
    print "%s: build request exists, skipping" % (instance_uuid,)
    break

  # Check which cell contains this instance
  for cell in CELLS:
    cell['db'].execute("SELECT id FROM instances WHERE uuid = %s", (instance_uuid,))

    if cell['db'].rowcount != 0:
      instance_cell = cell
      break

  # Update to the correct cell
  if instance_cell:
    print "UPDATE instance_mappings SET cell_id = '%s' WHERE instance_uuid = '%s';" % (instance_cell['id'], instance_uuid)
    continue

  # If we reach this point, it's not in any cell?!
  print "%s: not found in any cell" % (instance_uuid)
================================================================================