swarming: read configs from luci-config

appengine/swarming/server/config.py

 # Copyright 2013 The LUCI Authors. All rights reserved.
 # Use of this source code is governed by the Apache v2.0 license that can be
 # found in the LICENSE file.
 
 """Instance specific settings."""
 
-from google.appengine.ext import ndb
+import logging
+import posixpath
 
-from components.datastore_utils import config
+from components import config
+from components import gitiles
+from components import net
+from components import utils
+from components.config import validation
+
+from proto import config_pb2
+
+SETTINGS_CFG_FILENAME = 'settings.cfg'
 
 
-class GlobalConfig(config.GlobalConfig):
-  """Application wide settings."""
-  # id to inject into pages if applicable.
-  google_analytics = ndb.StringProperty(indexed=False, default='')
-
-  # The number of seconds an old task can be deduped from.
-  reusable_task_age_secs = ndb.IntegerProperty(
-      indexed=False, default=7*24*60*60)
-
-  # The amount of time that has to pass before a machine is considered dead.
-  bot_death_timeout_secs = ndb.IntegerProperty(default=10*60)
-
-  # Enable ts_mon based monitoring.
-  enable_ts_monitoring = ndb.BooleanProperty(indexed=False, default=False)
+ConfigApi = config.ConfigApi
 
 
-def settings(fresh=False):
-  """Loads GlobalConfig or a default one if not present.
+@validation.self_rule(SETTINGS_CFG_FILENAME, config_pb2.SettingsCfg)
+def validate_settings(cfg, ctx):
+  """Validates settings.cfg file against proto message schema."""
+  def within_year(value):
+    if value < 0:
+      ctx.error('cannot be negative')
+    elif value > 60 * 60 * 24 * 365:
+      ctx.error('cannot be more than a year')
 
-  If fresh=True, a full fetch from NDB is done.
+  with ctx.prefix('bot_death_timeout_secs '):
+    within_year(cfg.bot_death_timeout_secs)
+  with ctx.prefix('reusable_task_age_secs '):
+    within_year(cfg.reusable_task_age_secs)
+
+
+@utils.memcache('config:get_configs_url', time=60)
+def _get_configs_url():
+  """Returns URL where luci-config fetches configs from."""
+  url = None
+  try:
+    url = config.get_config_set_location(config.self_config_set())
+  except net.Error:
+    logging.info(
+        'Could not get configs URL. Possibly config directory for this '
+        'instance of swarming does not exist')
+  return url or 'about:blank'
+
+
+def _gitiles_url(configs_url, rev, path):
+  """URL to a directory in gitiles -> URL to a file at concrete revision."""
+  try:
+    loc = gitiles.Location.parse(configs_url)
+    return str(loc._replace(
+        treeish=rev or loc.treeish,
+        path=posixpath.join(loc.path, path)))
+  except ValueError:
+    # Not a gitiles URL, return as is.
+    return configs_url
+
+
+def _get_settings():
+  """Returns (rev, cfg) where cfg is a parsed SettingsCfg message.
+
+  If config does not exists, returns (None, <cfg with defaults>).
+
+  The config is cached in the datastore.
   """
-  if fresh:
-    GlobalConfig.clear_cache()
-  return GlobalConfig.cached()
+  rev = None
+  cfg = None
+  try:
+    # store_last_good=True tells config component to update the config file
+    # in a cron job. Here we just read from datastore.
+    rev, cfg = config.get_self_config(
+        SETTINGS_CFG_FILENAME, config_pb2.SettingsCfg, store_last_good=True)
+  except config.CannotLoadConfigError as ex:
+    logging.info('Could not load settings.cfg: %s; using defaults', ex)
+  if not cfg:
+    cfg = config_pb2.SettingsCfg(
+        reusable_task_age_secs=7*24*60*60,
+        bot_death_timeout_secs=10*60)
+  return rev, cfg
+
+
+def settings_info():
+  """Returns information about the settings file.
+
+  Returns a dict with keys:
+    'cfg': parsed SettingsCfg message
+    'rev': revision of cfg
+    'rev_url': URL of a human-consumable page that displays the config
+    'config_service_url': URL of the config_service.
+  """
+  rev, cfg = _get_settings()
+  rev_url = _gitiles_url(_get_configs_url(), rev, SETTINGS_CFG_FILENAME)
+  cfg_service_hostname = config.config_service_hostname()
+  return {
+    'cfg': cfg,
+    'rev': rev,
+    'rev_url': rev_url,
+    'config_service_url': (
+        'https://%s' % cfg_service_hostname if cfg_service_hostname else ''
+    ),
+  }
+
+
+def settings():
+  """Loads settings from an NDB-based cache or a default one if not present."""
+  return _get_settings()[1]