def main(self):
# Continue looping while the service is running.
while not self._terminate_flag:
# This blocks on changes to the watched key in etcd.
_log.debug("Waiting for change from etcd for key {}".format(
self._plugin.key()))
old_value = self._last_value
value = self.update_from_etcd()
if self._terminate_flag:
break
if value and value != old_value:
_log.info("Got new config value from etcd - filename {}, file size {}, SHA512 hash {}".format(
self._plugin.file(),
len(value),
sha512(utils.safely_encode(value)).hexdigest()))
_log.debug("Got new config value from etcd:\n{}".format(
utils.safely_encode(value)))
self._plugin.on_config_changed(value, self._alarm)
FILE_CHANGED.log(filename=self._plugin.file())
def test_safely_encode(self):
self.assertEquals(safely_encode(None), None)
self.assertEquals(safely_encode(u'ASCII'), 'ASCII')
self.assertEquals(safely_encode(u'\x80nonASCII'), '\xc2\x80nonASCII')
def test_safely_encode(self):
self.assertEquals(safely_encode(None), None)
self.assertEquals(safely_encode(u'ASCII'), 'ASCII')
self.assertEquals(safely_encode(u'\x80nonASCII'), '\xc2\x80nonASCII')
def read_from_etcd(self, wait=True):
result = None
wait_index = None
try:
result = self._client.read(self.key(), quorum=True)
wait_index = result.etcd_index + 1
if wait:
# If the cluster view hasn't changed since we last saw it, then
# wait for it to change before doing anything else.
_log.info("Read value {} from etcd, "
"comparing to last value {}".format(
utils.safely_encode(result.value),
utils.safely_encode(self._last_value)))
if result.value == self._last_value:
_log.info("Watching for changes with {}".format(wait_index))
while not self._terminate_flag and not self._abort_read and self.is_running():
_log.debug("Started a new watch")
try:
result = self._client.read(self.key(),
timeout=self.TIMEOUT_ON_WATCH,
waitIndex=wait_index,
wait=True,
recursive=False)
break
except etcd.EtcdException as e:
if "Read timed out" in e.message:
# Timeouts after TIMEOUT_ON_WATCH seconds are expected, so
# ignore them - unless we're terminating, we'll
# stay in the while loop and try again
pass
else:
raise
_log.debug("Finished watching")
# Return if we're terminating.
if self._terminate_flag:
return self.tuple_from_result(result)
except etcd.EtcdKeyError:
_log.info("Key {} doesn't exist in etcd yet".format(self.key()))
# Use any value on disk first, but the default value if not found
try:
f = open(self._plugin.file(), 'r')
value = f.read() # pragma: no cover
except:
value = self.default_value()
# Attempt to create new key in etcd.
try:
# The prevExist set to False will fail the write if it finds a
# key already in etcd. This stops us overwriting a manually
# uploaded file with the default template.
self._client.write(self.key(), value, prevExist=False)
return (value, None)
except: # pragma: no cover
_log.debug("Failed to create new key in the etcd store")
# Sleep briefly to avoid hammering a non-existent key
sleep(self.PAUSE_BEFORE_RETRY_ON_MISSING_KEY)
# Return 'None' so that plugins do not write config to disk
# that does not exist in the etcd store, leaving us out of sync
return (None, None)
except Exception as e:
# Catch-all error handler (for invalid requests, timeouts, etc -
# start over.
_log.error("{} caught {!r} when trying to read with index {}"
" - pause before retry".
format(self._ip, e, wait_index))
# Sleep briefly to avoid hammering a failed server
self.pause()
# The main loop (which reads from etcd in a loop) should call this
# function again after we return, causing the read to be retried.
return self.tuple_from_result(result)
def read_from_etcd(self, wait=True):
result = None
wait_index = None
try:
result = self._client.read(self.key(), quorum=True)
wait_index = result.etcd_index + 1
if wait:
# If the cluster view hasn't changed since we last saw it, then
# wait for it to change before doing anything else.
_log.info("Read value {} from etcd, "
"comparing to last value {}".format(
utils.safely_encode(result.value),
utils.safely_encode(self._last_value)))
if result.value == self._last_value:
_log.info(
"Watching for changes with {}".format(wait_index))
while not self._terminate_flag and not self._abort_read and self.is_running(
):
_log.debug("Started a new watch")
try:
result = self._client.read(
self.key(),
timeout=self.TIMEOUT_ON_WATCH,
waitIndex=wait_index,
wait=True,
recursive=False)
break
except etcd.EtcdException as e:
if "Read timed out" in e.message:
# Timeouts after TIMEOUT_ON_WATCH seconds are expected, so
# ignore them - unless we're terminating, we'll
# stay in the while loop and try again
pass
else:
raise
_log.debug("Finished watching")
# Return if we're terminating.
if self._terminate_flag:
return self.tuple_from_result(result)
except etcd.EtcdKeyError:
_log.info("Key {} doesn't exist in etcd yet".format(self.key()))
# Use any value on disk first, but the default value if not found
try:
f = open(self._plugin.file(), 'r')
value = f.read() # pragma: no cover
except:
value = self.default_value()
# Attempt to create new key in etcd.
try:
# The prevExist set to False will fail the write if it finds a
# key already in etcd. This stops us overwriting a manually
# uploaded file with the default template.
self._client.write(self.key(), value, prevExist=False)
return (value, None)
except: # pragma: no cover
_log.debug("Failed to create new key in the etcd store")
# Sleep briefly to avoid hammering a non-existent key
sleep(self.PAUSE_BEFORE_RETRY_ON_MISSING_KEY)
# Return 'None' so that plugins do not write config to disk
# that does not exist in the etcd store, leaving us out of sync
return (None, None)
except Exception as e:
# Catch-all error handler (for invalid requests, timeouts, etc -
# start over.
_log.error("{} caught {!r} when trying to read with index {}"
" - pause before retry".format(self._ip, e, wait_index))
# Sleep briefly to avoid hammering a failed server
self.pause()
# The main loop (which reads from etcd in a loop) should call this
# function again after we return, causing the read to be retried.
return self.tuple_from_result(result)