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1
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""" |
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A worker handles the connection to both, Kafka and InfluxDB and handles encoding in between. |
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3
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""" |
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import logging |
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5
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import time |
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6
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import sys |
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7
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from requests.exceptions import ConnectionError |
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8
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from influxdb.exceptions import InfluxDBServerError, InfluxDBClientError |
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9
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from kafka_influxdb.encoder.errors import EncoderError |
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10
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11
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12
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class Worker(object): |
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""" |
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14
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Implementation of worker class that handles Kafka and InfluxDB |
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15
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connections and manages message encoding. |
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""" |
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def __init__(self, reader, encoder, writer, config): |
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""" |
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Setup |
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""" |
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self.config = config |
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self.reader = reader |
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23
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self.encoder = encoder |
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24
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self.writer = writer |
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25
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self.buffer = [] |
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26
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27
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# Field for time measurement |
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self.start_time = None |
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29
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self.last_flush_time = None |
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30
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31
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def consume(self): |
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32
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""" |
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33
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Run loop. Consume messages from reader, convert it to the |
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34
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output format using encoder and write to output with writer |
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35
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""" |
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36
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self.init_database() |
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37
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38
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logging.info("Listening for messages on Kafka topic %s...", self.config.kafka_topic) |
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self.start_time = self.last_flush_time = time.time() |
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40
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while True: |
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try: |
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for index, raw_message in enumerate(self.reader.read(), 1): |
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if raw_message: |
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self.buffer.extend(self.encoder.encode(raw_message)) |
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45
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if index % self.config.buffer_size == 0: |
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46
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self.flush() |
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47
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elif (self.config.buffer_timeout and len(self.buffer) > 0 and |
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48
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(time.time() - self.last_flush_time) >= self.config.buffer_timeout): |
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49
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logging.debug("Buffer timeout %ss. Flushing remaining %s messages from buffer.", |
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50
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self.config.buffer_timeout, len(self.buffer)) |
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51
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self.flush() |
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52
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except EncoderError: |
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53
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logging.error("Encoder error. Trying to reconnect to %s:%s", |
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54
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self.config.kafka_host, self.config.kafka_port) |
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55
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logging.debug("Sleeping for %d ms before reconnect", |
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56
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self.config.reconnect_wait_time_ms) |
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57
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time.sleep(self.config.reconnect_wait_time_ms / 1000.0) |
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58
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except KeyboardInterrupt: |
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59
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logging.info("Shutdown. Flushing remaining messages from buffer.") |
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60
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self.flush() |
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61
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break |
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62
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except SystemExit: |
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63
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break |
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64
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65
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def init_database(self): |
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66
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""" |
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67
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Initialize the InfluxDB database if it is not already there |
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68
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""" |
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69
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try: |
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70
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logging.info("Creating InfluxDB database if not exists: %s", |
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71
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self.config.influxdb_dbname) |
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72
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self.writer.create_database(self.config.influxdb_dbname) |
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73
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except (ConnectionError, InfluxDBServerError, InfluxDBClientError) as error: |
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logging.error("Error while creating InfluxDB datbase: %s", error) |
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75
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sys.exit(2) |
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76
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77
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def flush(self): |
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78
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""" |
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79
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Flush values with writer |
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80
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""" |
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81
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if not self.buffer: |
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82
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# Don't do anything when buffer empty |
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83
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return |
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84
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try: |
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85
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self.last_flush_time = time.time() |
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86
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self.writer.write(self.buffer) |
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87
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if self.config.statistics: |
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88
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self.show_statistics() |
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89
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except (InfluxDBServerError, InfluxDBClientError) as influx_error: |
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90
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logging.error("Error while writing to InfluxDB: %s", influx_error) |
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91
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finally: |
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92
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self.buffer = [] |
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93
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94
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def show_statistics(self): |
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95
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""" |
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96
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Print performance metrics to stdout |
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97
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""" |
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98
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delta = time.time() - self.start_time |
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99
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msg_per_sec = self.config.buffer_size / delta |
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100
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print("Flushing output buffer. {0:.2f} messages/s".format(msg_per_sec)) |
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101
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# Reset timer |
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102
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self.start_time = time.time() |
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103
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104
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def set_reader(self, reader): |
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105
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self.reader = reader |
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106
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107
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def get_reader(self): |
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108
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return self.reader |
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109
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110
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def set_writer(self, writer): |
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111
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self.writer = writer |
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112
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113
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def get_writer(self): |
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114
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return self.writer |
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115
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116
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def get_buffer(self): |
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117
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return self.buffer |
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118
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119
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def get_config(self): |
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120
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return self.config |
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121
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mre /
kafka-influxdb
