Reading data from a stream in the AWS SDK

You can get data from a stream using the get_shard_iterator and get_record/get_records methods. When you invoke this method, you should specify the following parameters:

• Name of the stream, e.g., example-stream.
• ID of the cloud the stream is located in, e.g., b1gi1kuj2dht********.
• YDB database ID with the stream, e.g., cc8028jgtuab********.

You also need to configure the AWS SDK and assign the service account the yds.viewer role.

To read records from a stream with the parameters specified above:

1. Create a file named stream_get_records.py and copy the following code into it:

   import boto3
   from pprint import pprint
   import itertools
   
   def get_records(cloud, database, stream_name):
       client = boto3.client('kinesis', endpoint_url="https://yds.serverless.yandexcloud.net")
   
       StreamName = "/ru-central1/{cloud}/{database}/{stream}".format(cloud=cloud,
                                                                    database=database,
                                                                    stream=stream_name)
   
   
       describe_stream_result = client.describe_stream(StreamName=StreamName)
       shard_iterators = {}
   
       shards = [shard["ShardId"] for shard in describe_stream_result['StreamDescription']['Shards']]
   
       for shard_id in itertools.cycle(shards):
           if shard_id not in shard_iterators:
               shard_iterators[shard_id] = client.get_shard_iterator(StreamName=StreamName,
                                                                    ShardId=shard_id,
                                                                    ShardIteratorType='LATEST')['ShardIterator']
   
           record_response = client.get_records(ShardIterator=shard_iterators[shard_id])
           if "Records" in record_response:
               for record in [record for record in record_response["Records"]]:
                   yield record["Data"]
   
           if "NextShardIterator" in record_response:
               shard_iterators[shard_id] = record_response["NextShardIterator"]
   
   
   if __name__ == '__main__':
       for record in get_records(cloud="b1gi1kuj2dht********",
                                 database="cc8028jgtuab********",
                                 stream_name="example-stream"):
           pprint(record)    
           print("The record has been read successfully")
   

2. Run the program:

   python3 stream_get_records.py
   

   Result:

   The record has been read successfully
   b'{"user_id":"user1","score":100}'
   The record has been read successfully
   b'{"user_id":"user1","score":100}'
   ...