class LDClient(object):
"""The LaunchDarkly SDK client object.
Applications should configure the client at startup time and continue to use it throughout the lifetime
of the application, rather than creating instances on the fly. The best way to do this is with the
singleton methods :func:`ldclient.set_sdk_key()`, :func:`ldclient.set_config()`, and :func:`ldclient.get()`.
However, you may also call the constructor directly if you need to maintain multiple instances.
Client instances are thread-safe.
"""
def __init__(self, sdk_key=None, config=None, start_wait=5):
"""Constructs a new LDClient instance.
:param string sdk_key: the SDK key for your LaunchDarkly environment
:param ldclient.config.Config config: optional custom configuration
:param float start_wait: the number of seconds to wait for a successful connection to LaunchDarkly
"""
check_uwsgi()
if config is not None and config.sdk_key is not None and sdk_key is not None:
raise Exception(
"LaunchDarkly client init received both sdk_key and config with sdk_key. "
"Only one of either is expected")
if sdk_key is not None:
log.warn(
"Deprecated sdk_key argument was passed to init. Use config object instead."
)
self._config = Config(sdk_key=sdk_key)
else:
self._config = config or Config.default()
self._config._validate()
self._event_processor = None
self._lock = Lock()
self._store = _FeatureStoreClientWrapper(self._config.feature_store)
""" :type: FeatureStore """
if self._config.offline or not self._config.send_events:
self._event_processor = NullEventProcessor()
else:
self._event_processor = self._config.event_processor_class(
self._config)
if self._config.offline:
log.info("Started LaunchDarkly Client in offline mode")
return
if self._config.use_ldd:
log.info("Started LaunchDarkly Client in LDD mode")
return
update_processor_ready = threading.Event()
if self._config.update_processor_class:
log.info("Using user-specified update processor: " +
str(self._config.update_processor_class))
self._update_processor = self._config.update_processor_class(
self._config, self._store, update_processor_ready)
else:
if self._config.feature_requester_class:
feature_requester = self._config.feature_requester_class(
self._config)
else:
feature_requester = FeatureRequesterImpl(self._config)
""" :type: FeatureRequester """
if self._config.stream:
self._update_processor = StreamingUpdateProcessor(
self._config, feature_requester, self._store,
update_processor_ready)
else:
log.info("Disabling streaming API")
log.warn(
"You should only disable the streaming API if instructed to do so by LaunchDarkly support"
)
self._update_processor = PollingUpdateProcessor(
self._config, feature_requester, self._store,
update_processor_ready)
""" :type: UpdateProcessor """
self._update_processor.start()
log.info("Waiting up to " + str(start_wait) +
" seconds for LaunchDarkly client to initialize...")
update_processor_ready.wait(start_wait)
if self._update_processor.initialized() is True:
log.info("Started LaunchDarkly Client: OK")
else:
log.warn(
"Initialization timeout exceeded for LaunchDarkly Client or an error occurred. "
"Feature Flags may not yet be available.")
def get_sdk_key(self):
"""Returns the configured SDK key.
:rtype: string
"""
return self._config.sdk_key
def close(self):
"""Releases all threads and network connections used by the LaunchDarkly client.
Do not attempt to use the client after calling this method.
"""
log.info("Closing LaunchDarkly client..")
if self.is_offline():
return
if self._event_processor:
self._event_processor.stop()
if self._config.use_ldd:
return
if self._update_processor and self._update_processor.is_alive():
self._update_processor.stop()
def _send_event(self, event):
self._event_processor.send_event(event)
def track(self, event_name, user, data=None):
"""Tracks that a user performed an event.
LaunchDarkly automatically tracks pageviews and clicks that are specified in the Goals
section of the dashboard. This can be used to track custom goals or other events that do
not currently have goals.
:param string event_name: the name of the event, which may correspond to a goal in A/B tests
:param dict user: the attributes of the user
:param data: optional additional data associated with the event
"""
if user is None or user.get('key') is None:
log.warn("Missing user or user key when calling track().")
else:
self._send_event({
'kind': 'custom',
'key': event_name,
'user': user,
'data': data
})
def identify(self, user):
"""Registers the user.
This simply creates an analytics event that will transmit the given user properties to
LaunchDarkly, so that the user will be visible on your dashboard even if you have not
evaluated any flags for that user. It has no other effect.
:param dict user: attributes of the user to register
"""
if user is None or user.get('key') is None:
log.warn("Missing user or user key when calling identify().")
else:
self._send_event({
'kind': 'identify',
'key': str(user.get('key')),
'user': user
})
def is_offline(self):
"""Returns true if the client is in offline mode.
:rtype: bool
"""
return self._config.offline
def is_initialized(self):
"""Returns true if the client has successfully connected to LaunchDarkly.
If this returns false, it means that the client has not yet successfully connected to LaunchDarkly.
It might still be in the process of starting up, or it might be attempting to reconnect after an
unsuccessful attempt, or it might have received an unrecoverable error (such as an invalid SDK key)
and given up.
:rtype: bool
"""
return self.is_offline(
) or self._config.use_ldd or self._update_processor.initialized()
def flush(self):
"""Flushes all pending analytics events.
Normally, batches of events are delivered in the background at intervals determined by the
``flush_interval`` property of :class:`ldclient.config.Config`. Calling ``flush()``
schedules the next event delivery to be as soon as possible; however, the delivery still
happens asynchronously on a worker thread, so this method will return immediately.
"""
if self._config.offline:
return
return self._event_processor.flush()
def toggle(self, key, user, default):
"""Deprecated synonym for :func:`variation()`.
.. deprecated:: 2.0.0
"""
log.warn(
"Deprecated method: toggle() called. Use variation() instead.")
return self.variation(key, user, default)
def variation(self, key, user, default):
"""Determines the variation of a feature flag for a user.
:param string key: the unique key for the feature flag
:param dict user: a dictionary containing parameters for the end user requesting the flag
:param object default: the default value of the flag, to be used if the value is not
available from LaunchDarkly
:return: one of the flag's variation values, or the default value
"""
return self._evaluate_internal(key, user, default, False).value
def variation_detail(self, key, user, default):
"""Determines the variation of a feature flag for a user, like :func:`variation()`, but also
provides additional information about how this value was calculated, in the form of an
:class:`ldclient.flag.EvaluationDetail` object.
Calling this method also causes the "reason" data to be included in analytics events,
if you are capturing detailed event data for this flag.
:param string key: the unique key for the feature flag
:param dict user: a dictionary containing parameters for the end user requesting the flag
:param object default: the default value of the flag, to be used if the value is not
available from LaunchDarkly
:return: an object describing the result
:rtype: EvaluationDetail
"""
return self._evaluate_internal(key, user, default, True)
def _evaluate_internal(self, key, user, default,
include_reasons_in_events):
default = self._config.get_default(key, default)
if self._config.offline:
return EvaluationDetail(default, None,
error_reason('CLIENT_NOT_READY'))
def send_event(value, variation=None, flag=None, reason=None):
self._send_event({
'kind':
'feature',
'key':
key,
'user':
user,
'value':
value,
'variation':
variation,
'default':
default,
'version':
flag.get('version') if flag else None,
'trackEvents':
flag.get('trackEvents') if flag else None,
'debugEventsUntilDate':
flag.get('debugEventsUntilDate') if flag else None,
'reason':
reason if include_reasons_in_events else None
})
if not self.is_initialized():
if self._store.initialized:
log.warn(
"Feature Flag evaluation attempted before client has initialized - using last known values from feature store for feature key: "
+ key)
else:
log.warn(
"Feature Flag evaluation attempted before client has initialized! Feature store unavailable - returning default: "
+ str(default) + " for feature key: " + key)
reason = error_reason('CLIENT_NOT_READY')
send_event(default, None, None, reason)
return EvaluationDetail(default, None, reason)
if user is not None and user.get('key', "") == "":
log.warn(
"User key is blank. Flag evaluation will proceed, but the user will not be stored in LaunchDarkly."
)
try:
flag = self._store.get(FEATURES, key, lambda x: x)
except Exception as e:
log.error(
"Unexpected error while retrieving feature flag \"%s\": %s" %
(key, repr(e)))
log.debug(traceback.format_exc())
reason = error_reason('EXCEPTION')
send_event(default, None, None, reason)
return EvaluationDetail(default, None, reason)
if not flag:
reason = error_reason('FLAG_NOT_FOUND')
send_event(default, None, None, reason)
return EvaluationDetail(default, None, reason)
else:
if user is None or user.get('key') is None:
reason = error_reason('USER_NOT_SPECIFIED')
send_event(default, None, flag, reason)
return EvaluationDetail(default, None, reason)
try:
result = evaluate(flag, user, self._store,
include_reasons_in_events)
for event in result.events or []:
self._send_event(event)
detail = result.detail
if detail.is_default_value():
detail = EvaluationDetail(default, None, detail.reason)
send_event(detail.value, detail.variation_index, flag,
detail.reason)
return detail
except Exception as e:
log.error(
"Unexpected error while evaluating feature flag \"%s\": %s"
% (key, repr(e)))
log.debug(traceback.format_exc())
reason = error_reason('EXCEPTION')
send_event(default, None, flag, reason)
return EvaluationDetail(default, None, reason)
def all_flags(self, user):
"""Returns all feature flag values for the given user.
This method is deprecated - please use :func:`all_flags_state()` instead. Current versions of the
client-side SDK will not generate analytics events correctly if you pass the result of ``all_flags``.
:param dict user: the end user requesting the feature flags
:return: a dictionary of feature flag keys to values; returns None if the client is offline,
has not been initialized, or the user is None or has no key
:rtype: dict
"""
state = self.all_flags_state(user)
if not state.valid:
return None
return state.to_values_map()
def all_flags_state(self, user, **kwargs):
"""Returns an object that encapsulates the state of all feature flags for a given user,
including the flag values and also metadata that can be used on the front end. See the
JavaScript SDK Reference Guide on
`Bootstrapping <https://docs.launchdarkly.com/docs/js-sdk-reference#section-bootstrapping>`_.
This method does not send analytics events back to LaunchDarkly.
:param dict user: the end user requesting the feature flags
:param kwargs: optional parameters affecting how the state is computed - see below
:Keyword Arguments:
* **client_side_only** (*boolean*) --
set to True to limit it to only flags that are marked for use with the client-side SDK
(by default, all flags are included)
* **with_reasons** (*boolean*) --
set to True to include evaluation reasons in the state (see :func:`variation_detail()`)
* **details_only_for_tracked_flags** (*boolean*) --
set to True to omit any metadata that is normally only used for event generation, such
as flag versions and evaluation reasons, unless the flag has event tracking or debugging
turned on
:return: a FeatureFlagsState object (will never be None; its ``valid`` property will be False
if the client is offline, has not been initialized, or the user is None or has no key)
:rtype: FeatureFlagsState
"""
if self._config.offline:
log.warn(
"all_flags_state() called, but client is in offline mode. Returning empty state"
)
return FeatureFlagsState(False)
if not self.is_initialized():
if self._store.initialized:
log.warn(
"all_flags_state() called before client has finished initializing! Using last known values from feature store"
)
else:
log.warn(
"all_flags_state() called before client has finished initializing! Feature store unavailable - returning empty state"
)
return FeatureFlagsState(False)
if user is None or user.get('key') is None:
log.warn(
"User or user key is None when calling all_flags_state(). Returning empty state."
)
return FeatureFlagsState(False)
state = FeatureFlagsState(True)
client_only = kwargs.get('client_side_only', False)
with_reasons = kwargs.get('with_reasons', False)
details_only_if_tracked = kwargs.get('details_only_for_tracked_flags',
False)
try:
flags_map = self._store.all(FEATURES, lambda x: x)
if flags_map is None:
raise ValueError("feature store error")
except Exception as e:
log.error("Unable to read flags for all_flag_state: %s" % repr(e))
return FeatureFlagsState(False)
for key, flag in flags_map.items():
if client_only and not flag.get('clientSide', False):
continue
try:
detail = evaluate(flag, user, self._store, False).detail
state.add_flag(flag, detail.value, detail.variation_index,
detail.reason if with_reasons else None,
details_only_if_tracked)
except Exception as e:
log.error(
"Error evaluating flag \"%s\" in all_flags_state: %s" %
(key, repr(e)))
log.debug(traceback.format_exc())
reason = {'kind': 'ERROR', 'errorKind': 'EXCEPTION'}
state.add_flag(flag, None, None,
reason if with_reasons else None,
details_only_if_tracked)
return state
def secure_mode_hash(self, user):
"""Computes an HMAC signature of a user signed with the client's SDK key,
for use with the JavaScript SDK.
For more information, see the JavaScript SDK Reference Guide on
`Secure mode <https://github.com/launchdarkly/js-client#secure-mode>`_.
:param dict user: the attributes of the user
:return: a hash string that can be passed to the front end
:rtype: string
"""
if user.get('key') is None or self._config.sdk_key is None:
return ""
return hmac.new(self._config.sdk_key.encode(),
user.get('key').encode(), hashlib.sha256).hexdigest()
class LDClient(object):
def __init__(self, sdk_key=None, config=None, start_wait=5):
"""Constructs a new LDClient instance.
Rather than calling this constructor directly, you can call the `ldclient.set_sdk_key`,
`ldclient.set_config`, and `ldclient.get` functions to configure and use a singleton
client instance.
:param string sdk_key: the SDK key for your LaunchDarkly environment
:param Config config: optional custom configuration
:param float start_wait: the number of seconds to wait for a successful connection to LaunchDarkly
"""
check_uwsgi()
if config is not None and config.sdk_key is not None and sdk_key is not None:
raise Exception("LaunchDarkly client init received both sdk_key and config with sdk_key. "
"Only one of either is expected")
if sdk_key is not None:
log.warn("Deprecated sdk_key argument was passed to init. Use config object instead.")
self._config = Config(sdk_key=sdk_key)
else:
self._config = config or Config.default()
self._config._validate()
self._event_processor = None
self._lock = Lock()
self._store = self._config.feature_store
""" :type: FeatureStore """
if self._config.offline or not self._config.send_events:
self._event_processor = NullEventProcessor()
else:
self._event_processor = self._config.event_processor_class(self._config)
if self._config.offline:
log.info("Started LaunchDarkly Client in offline mode")
return
if self._config.use_ldd:
log.info("Started LaunchDarkly Client in LDD mode")
return
update_processor_ready = threading.Event()
if self._config.update_processor_class:
log.info("Using user-specified update processor: " + str(self._config.update_processor_class))
self._update_processor = self._config.update_processor_class(
self._config, self._store, update_processor_ready)
else:
if self._config.feature_requester_class:
feature_requester = self._config.feature_requester_class(self._config)
else:
feature_requester = FeatureRequesterImpl(self._config)
""" :type: FeatureRequester """
if self._config.stream:
self._update_processor = StreamingUpdateProcessor(
self._config, feature_requester, self._store, update_processor_ready)
else:
log.info("Disabling streaming API")
log.warn("You should only disable the streaming API if instructed to do so by LaunchDarkly support")
self._update_processor = PollingUpdateProcessor(
self._config, feature_requester, self._store, update_processor_ready)
""" :type: UpdateProcessor """
self._update_processor.start()
log.info("Waiting up to " + str(start_wait) + " seconds for LaunchDarkly client to initialize...")
update_processor_ready.wait(start_wait)
if self._update_processor.initialized() is True:
log.info("Started LaunchDarkly Client: OK")
else:
log.warn("Initialization timeout exceeded for LaunchDarkly Client or an error occurred. "
"Feature Flags may not yet be available.")
def get_sdk_key(self):
"""Returns the configured SDK key.
:rtype: string
"""
return self._config.sdk_key
def close(self):
"""Releases all threads and network connections used by the LaunchDarkly client.
Do not attempt to use the client after calling this method.
"""
log.info("Closing LaunchDarkly client..")
if self.is_offline():
return
if self._event_processor:
self._event_processor.stop()
if self._update_processor and self._update_processor.is_alive():
self._update_processor.stop()
def _send_event(self, event):
self._event_processor.send_event(event)
def track(self, event_name, user, data=None):
"""Tracks that a user performed an event.
:param string event_name: The name of the event.
:param dict user: The attributes of the user.
:param data: Optional additional data associated with the event.
"""
self._sanitize_user(user)
if user is None or user.get('key') is None:
log.warn("Missing user or user key when calling track().")
self._send_event({'kind': 'custom', 'key': event_name, 'user': user, 'data': data})
def identify(self, user):
"""Registers the user.
:param dict user: attributes of the user to register
"""
self._sanitize_user(user)
if user is None or user.get('key') is None:
log.warn("Missing user or user key when calling identify().")
self._send_event({'kind': 'identify', 'key': user.get('key'), 'user': user})
def is_offline(self):
"""Returns true if the client is in offline mode.
:rtype: bool
"""
return self._config.offline
def is_initialized(self):
"""Returns true if the client has successfully connected to LaunchDarkly.
:rype: bool
"""
return self.is_offline() or self._config.use_ldd or self._update_processor.initialized()
def flush(self):
"""Flushes all pending events.
"""
if self._config.offline:
return
return self._event_processor.flush()
def toggle(self, key, user, default):
"""Deprecated synonym for `variation`.
"""
log.warn("Deprecated method: toggle() called. Use variation() instead.")
return self.variation(key, user, default)
def variation(self, key, user, default):
"""Determines the variation of a feature flag for a user.
:param string key: the unique key for the feature flag
:param dict user: a dictionary containing parameters for the end user requesting the flag
:param object default: the default value of the flag, to be used if the value is not
available from LaunchDarkly
:return: one of the flag's variation values, or the default value
"""
return self._evaluate_internal(key, user, default, False).value
def variation_detail(self, key, user, default):
"""Determines the variation of a feature flag for a user, like `variation`, but also
provides additional information about how this value was calculated.
The return value is an EvaluationDetail object, which has three properties:
`value`: the value that was calculated for this user (same as the return value
of `variation`)
`variation_index`: the positional index of this value in the flag, e.g. 0 for the
first variation - or `None` if the default value was returned
`reason`: a hash describing the main reason why this value was selected.
The `reason` will also be included in analytics events, if you are capturing
detailed event data for this flag.
:param string key: the unique key for the feature flag
:param dict user: a dictionary containing parameters for the end user requesting the flag
:param object default: the default value of the flag, to be used if the value is not
available from LaunchDarkly
:return: an EvaluationDetail object describing the result
:rtype: EvaluationDetail
"""
return self._evaluate_internal(key, user, default, True)
def _evaluate_internal(self, key, user, default, include_reasons_in_events):
default = self._config.get_default(key, default)
if self._config.offline:
return EvaluationDetail(default, None, error_reason('CLIENT_NOT_READY'))
if user is not None:
self._sanitize_user(user)
def send_event(value, variation=None, flag=None, reason=None):
self._send_event({'kind': 'feature', 'key': key, 'user': user,
'value': value, 'variation': variation, 'default': default,
'version': flag.get('version') if flag else None,
'trackEvents': flag.get('trackEvents') if flag else None,
'debugEventsUntilDate': flag.get('debugEventsUntilDate') if flag else None,
'reason': reason if include_reasons_in_events else None})
if not self.is_initialized():
if self._store.initialized:
log.warn("Feature Flag evaluation attempted before client has initialized - using last known values from feature store for feature key: " + key)
else:
log.warn("Feature Flag evaluation attempted before client has initialized! Feature store unavailable - returning default: "
+ str(default) + " for feature key: " + key)
reason = error_reason('CLIENT_NOT_READY')
send_event(default, None, None, reason)
return EvaluationDetail(default, None, reason)
if user is not None and user.get('key', "") == "":
log.warn("User key is blank. Flag evaluation will proceed, but the user will not be stored in LaunchDarkly.")
flag = self._store.get(FEATURES, key, lambda x: x)
if not flag:
reason = error_reason('FLAG_NOT_FOUND')
send_event(default, None, None, reason)
return EvaluationDetail(default, None, reason)
else:
if user is None or user.get('key') is None:
reason = error_reason('USER_NOT_SPECIFIED')
send_event(default, None, flag, reason)
return EvaluationDetail(default, None, reason)
try:
result = evaluate(flag, user, self._store, include_reasons_in_events)
for event in result.events or []:
self._send_event(event)
detail = result.detail
if detail.is_default_value():
detail = EvaluationDetail(default, None, detail.reason)
send_event(detail.value, detail.variation_index, flag, detail.reason)
return detail
except Exception as e:
log.error("Unexpected error while evaluating feature flag \"%s\": %s" % (key, e))
log.debug(traceback.format_exc())
reason = error_reason('EXCEPTION')
send_event(default, None, flag, reason)
return EvaluationDetail(default, None, reason)
def all_flags(self, user):
"""Returns all feature flag values for the given user.
This method is deprecated - please use `all_flags_state` instead. Current versions of the
client-side SDK will not generate analytics events correctly if you pass the result of `all_flags`.
:param dict user: the end user requesting the feature flags
:return: a dictionary of feature flag keys to values; returns None if the client is offline,
has not been initialized, or the user is None or has no key
:rtype: dict
"""
state = self.all_flags_state(user)
if not state.valid:
return None
return state.to_values_map()
def all_flags_state(self, user, **kwargs):
"""Returns an object that encapsulates the state of all feature flags for a given user,
including the flag values and also metadata that can be used on the front end.
This method does not send analytics events back to LaunchDarkly.
:param dict user: the end user requesting the feature flags
:param kwargs: optional parameters affecting how the state is computed: set
`client_side_only=True` to limit it to only flags that are marked for use with the
client-side SDK (by default, all flags are included); set `with_reasons=True` to
include evaluation reasons in the state (see `variation_detail`)
:return: a FeatureFlagsState object (will never be None; its 'valid' property will be False
if the client is offline, has not been initialized, or the user is None or has no key)
:rtype: FeatureFlagsState
"""
if self._config.offline:
log.warn("all_flags_state() called, but client is in offline mode. Returning empty state")
return FeatureFlagsState(False)
if not self.is_initialized():
if self._store.initialized:
log.warn("all_flags_state() called before client has finished initializing! Using last known values from feature store")
else:
log.warn("all_flags_state() called before client has finished initializing! Feature store unavailable - returning empty state")
return FeatureFlagsState(False)
if user is None or user.get('key') is None:
log.warn("User or user key is None when calling all_flags_state(). Returning empty state.")
return FeatureFlagsState(False)
state = FeatureFlagsState(True)
client_only = kwargs.get('client_side_only', False)
with_reasons = kwargs.get('with_reasons', False)
try:
flags_map = self._store.all(FEATURES, lambda x: x)
except Exception as e:
log.error("Unable to read flags for all_flag_state: %s" % e)
return FeatureFlagsState(False)
for key, flag in flags_map.items():
if client_only and not flag.get('clientSide', False):
continue
try:
detail = evaluate(flag, user, self._store, False).detail
state.add_flag(flag, detail.value, detail.variation_index,
detail.reason if with_reasons else None)
except Exception as e:
log.error("Error evaluating flag \"%s\" in all_flags_state: %s" % (key, e))
log.debug(traceback.format_exc())
reason = {'kind': 'ERROR', 'errorKind': 'EXCEPTION'}
state.add_flag(flag, None, None, reason if with_reasons else None)
return state
def secure_mode_hash(self, user):
"""Generates a hash value for a user.
For more info: <a href="https://github.com/launchdarkly/js-client#secure-mode">https://github.com/launchdarkly/js-client#secure-mode</a>
:param dict user: the attributes of the user
:return: a hash string that can be passed to the front end
:rtype: string
"""
if user.get('key') is None or self._config.sdk_key is None:
return ""
return hmac.new(self._config.sdk_key.encode(), user.get('key').encode(), hashlib.sha256).hexdigest()
@staticmethod
def _sanitize_user(user):
if 'key' in user:
user['key'] = str(user['key'])