Updated on 2024-04-02 GMT+08:00

Python Sample Code

Function

Submit Flink Kafka read and write jobs to Yarn through Python APIs.

Sample Code

The main logic code in pyflink-kafka.py is provided. Before submitting the code, ensure that file_path is the path where the SQL statement to be executed. You are advised to use a full path.

For details about the complete code, see pyflink-kafka.py in flink-examples/pyflink-example/pyflink-kafka.
import os
import logging
import sys
from pyflink.common import JsonRowDeserializationSchema, JsonRowSerializationSchema
from pyflink.common.typeinfo import Types
from pyflink.datastream.connectors import FlinkKafkaProducer, FlinkKafkaConsumer
from pyflink.datastream import StreamExecutionEnvironment
from pyflink.table import TableEnvironment, EnvironmentSettings
def read_sql(file_path):
    if not os.path.isfile(file_path):
        raise TypeError(file_path + " does not exist")
    all_the_text = open(file_path).read()
    return all_the_text
def exec_sql():
    # Change the SQL path before job submission.
    # file_path = "/opt/client/Flink/flink/insertData2kafka.sql"
    # file_path = os.getcwd() + "/../../../../yarnship/insertData2kafka.sql"
    # file_path = "/opt/client/Flink/flink/conf/ssl/insertData2kafka.sql"
    file_path = "insertData2kafka.sql"
    sql = read_sql(file_path)
    t_env = TableEnvironment.create(EnvironmentSettings.in_streaming_mode())
    statement_set = t_env.create_statement_set()
    sqlArr = sql.split(";")
    for sqlStr in sqlArr:
        sqlStr = sqlStr.strip()
        if sqlStr.lower().startswith("create"):
            print("---------create---------------")
            print(sqlStr)
            t_env.execute_sql(sqlStr)
        if sqlStr.lower().startswith("insert"):
            print("---------insert---------------")
            print(sqlStr)
            statement_set.add_insert_sql(sqlStr)
    statement_set.execute()
def read_write_kafka():
    # find kafka connector jars
    env = StreamExecutionEnvironment.get_execution_environment()
    env.set_parallelism(1)
    specific_jars = "file:///opt/client/Flink/flink/lib/flink-connector-kafka-xxx.jar"
    # specific_jars = "file://" + os.getcwd() + "/../../../../yarnship/flink-connector-kafka-xxx.jar"
    # specific_jars = "file:///opt/client/Flink/flink/conf/ssl/flink-connector-kafka-xxx.jar"
    # the sql connector for kafka is used here as it's a fat jar and could avoid dependency issues
    env.add_jars(specific_jars)
    kafka_properties = {'bootstrap.servers': '192.168.20.162:21005', 'group.id': 'test_group'}
    deserialization_schema = JsonRowDeserializationSchema.builder() \
        .type_info(type_info=Types.ROW([Types.INT(), Types.STRING()])).build()
    kafka_consumer = FlinkKafkaConsumer(
        topics='test_source_topic',
        deserialization_schema=deserialization_schema,
        properties=kafka_properties)
    print("---------read ---------------")
    ds = env.add_source(kafka_consumer)
    serialization_schema = JsonRowSerializationSchema.builder().with_type_info(
        type_info=Types.ROW([Types.INT(), Types.STRING()])).build()
    kafka_producer = FlinkKafkaProducer(
        topic='test_sink_topic',
        serialization_schema=serialization_schema,
        producer_config=kafka_properties)
    print("--------write------------------")
    ds.add_sink(kafka_producer)
    env.execute("pyflink kafka test")
if __name__ == '__main__':
    logging.basicConfig(stream=sys.stdout, level=logging.INFO, format="%(message)s")
    print("------------------insert data to kafka----------------")
    exec_sql()
    print("------------------read_write_kafka----------------")
    read_write_kafka()
Table 1 Parameters for submitting a regular job using Python

Parameter

Description

Example

bootstrap.servers

Service IP address and port number of the Broker instance of Kafka

192.168.12.25:21005

specific_jars

Package path: Client installation directory/Flink/flink/lib/flink-connector-kafka-*.jar. You are advised to use a full path.

NOTE:

If a job needs to be submitted as yarn-application, replace the following path. Replace the JAR package version with the actual one.

specific_jars="file://"+os.getcwd()+"/../../../../yarnship/flink-connector-kafka-1.15.0-h0.cbu.mrs.330.r13.jar"

specific_jars = file:///Client installation directory/Flink/flink/lib/flink-connector-kafka-1.15.0-h0.cbu.mrs.330.r13.jar

file_path

Path of the insertData2kafka.sql file. You are advised to use a full path. Obtain the package from the secondary development sample code and upload it to the specified directory on the client.

NOTE:

If a job needs to be submitted as yarn-application, replace the following path:

file_path = os.getcwd() + "/../../../../yarnship/insertData2kafka.sql"

file_path = /Client installation directory/Flink/flink/insertData2kafka.sql

The following is an example SQL statement:
create table kafka_sink_table (
  age int,
  name varchar(10)
) with (
  'connector' = 'kafka',
'topic' = 'test_source_topic', --Name of the topic written to Kafka. Ensure that the topic name is the same as that in the Python file.
  'properties.bootstrap.servers' = 'IP address of the Kafka broker instance:Kafka port number',
  'properties.group.id' = 'test_group',
  'format' = 'json'
);
create TABLE datagen_source_table (
   age int,
  name varchar(10)
) WITH (
  'connector' = 'datagen',
  'rows-per-second' = '1'
);
INSERT INTO
  kafka_sink_table
SELECT
  *
FROM
  datagen_source_table;