Source code for

from time import sleep

from catcher.steps.check import Operator
from catcher.steps.external_step import ExternalStep
from catcher.steps.step import Step, update_variables
from catcher.utils.logger import debug
from catcher.utils.misc import try_get_object, fill_template_str
from catcher.utils.time_utils import to_seconds
from import MqStepMixin

[docs]class Kafka(ExternalStep, MqStepMixin): """ Allows you to consume/produce messages from/to Apache `Kafka <>`_ :Input: :consume: Consume message from kafka. - server: is the kafka host. Can be multiple, comma-separated. - group_id: is the consumer group id. If not specified - `catcher` will be used. *Optional* - topic: the name of the topic - timeout: is the consumer timeout. *Optional* (default is 1 sec) - where: search for specific message clause. *Optional* :produce: Produce message to kafka. - server: is the kafka host. Can be multiple, comma-separated. - topic: the name of the topic - data: data to be produced. - data_from_file: File can be used as data source. *Optional* Either `data` or `data_from_file` should present. :Examples: Read message with timestamp > 1000 :: kafka: consume: server: '' group_id: 'test' topic: 'test_consume_with_timestamp' timeout: {seconds: 5} where: equals: '{{ MESSAGE.timestamp > 1000 }}' Produce `data` variable as json message :: kafka: produce: server: '' topic: 'test_produce_json' data: '{{ data|tojson }}' """ def __init__(self, **kwargs: dict) -> None: super().__init__(**kwargs) method = Step.filter_predefined_keys(kwargs) # produce/consume self.method = method.lower() conf = kwargs[method] self.group_id = conf.get('group_id', 'catcher') self.server = conf.get('server', '') self.topic = conf['topic'] timeout = conf.get('timeout', {'seconds': 1}) self.timeout = to_seconds(timeout) self.where = conf.get('where', None) self.message = None if self.method != 'consume': self.message = conf.get('data', None) self.file = None if self.message is None: self.file = conf['data_from_file'] @update_variables def action(self, includes: dict, variables: dict) -> tuple: from pykafka import KafkaClient client = KafkaClient(hosts=fill_template_str(self.server, variables)) topic = client.topics[fill_template_str(self.topic, variables).encode('utf-8')] out = {} if self.method == 'consume': out = self.consume(topic, variables) if out is None: raise RuntimeError('No kafka messages were consumed') elif self.method == 'produce': self.produce(topic, variables) else: raise AttributeError('unknown method: ' + self.method) return variables, out def consume(self, topic, variables: dict) -> dict: from pykafka.common import OffsetType consumer = topic.get_simple_consumer(consumer_group=self.group_id.encode('utf-8'), auto_offset_reset=OffsetType.EARLIEST, reset_offset_on_start=False, consumer_timeout_ms=self.timeout * 1000) if self.where is not None: operator = Operator.find_operator(self.where) else: operator = None return Kafka.get_messages(consumer, operator, variables, self.timeout) def produce(self, topic, variables): message = self.form_body(self.message, self.file, variables) with topic.get_sync_producer() as producer: producer.produce(message.encode('utf-8')) @staticmethod def get_messages(consumer, where: Operator or None, variables, timeout) -> dict or None: try: while True: consumer.fetch() for message in consumer: value = try_get_object(message.value.decode('utf-8')) debug(value) if Kafka.check_message(where, value, variables): return value if timeout > 0: sleep(1) timeout -= 1 else: return None finally: consumer.commit_offsets() @staticmethod def check_message(where: Operator, message: str, variables: dict) -> bool: if where is None: return True variables = dict(variables) variables['MESSAGE'] = message return where.operation(variables)