Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Tutorial: Perform basic Kinesis Data Streams operations using the Amazon CLI

This section describes basic use of a Kinesis data stream from the command line using the Amazon CLI. Be sure you are familiar with the concepts discussed in Amazon Kinesis Data Streams Terminology and concepts.

Step 1: Create a stream

Your first step is to create a stream and verify that it was successfully created. Use the following command to create a stream named "Foo":

aws kinesis create-stream --stream-name Foo

Next, issue the following command to check on the stream's creation progress:

aws kinesis describe-stream-summary --stream-name Foo

You should get output that is similar to the following example:

{
    "StreamDescriptionSummary": {
        "StreamName": "Foo",
        "StreamARN": "arn:aws:kinesis:us-west-2:123456789012:stream/Foo",
        "StreamStatus": "CREATING",
        "RetentionPeriodHours": 48,
        "StreamCreationTimestamp": 1572297168.0,
        "EnhancedMonitoring": [
            {
                "ShardLevelMetrics": []
            }
        ],
        "EncryptionType": "NONE",
        "OpenShardCount": 3,
        "ConsumerCount": 0
    }
}

In this example, the stream has a status CREATING, which means it is not yet ready to use. Check again in a few moments, and you should see output similar to the following example:

{
    "StreamDescriptionSummary": {
        "StreamName": "Foo",
        "StreamARN": "arn:aws:kinesis:us-west-2:123456789012:stream/Foo",
        "StreamStatus": "ACTIVE",
        "RetentionPeriodHours": 48,
        "StreamCreationTimestamp": 1572297168.0,
        "EnhancedMonitoring": [
            {
                "ShardLevelMetrics": []
            }
        ],
        "EncryptionType": "NONE",
        "OpenShardCount": 3,
        "ConsumerCount": 0
    }
}
        

There is information in this output that you don't need for this tutorial. The important information for now is "StreamStatus": "ACTIVE", which tells you that the stream is ready to be used, and the information on the single shard that you requested. You can also verify the existence of your new stream by using the list-streams command, as shown here:

aws kinesis list-streams

Output:

{
    "StreamNames": [
        "Foo"
    ]
}

Step 2: Put a record

Now that you have an active stream, you are ready to put some data. For this tutorial, you will use the simplest possible command, put-record, which puts a single data record containing the text "testdata" into the stream:

aws kinesis put-record --stream-name Foo --partition-key 123 --data testdata

This command, if successful, will result in output similar to the following example:

{
    "ShardId": "shardId-000000000000",
    "SequenceNumber": "49546986683135544286507457936321625675700192471156785154"
}

Congratulations, you just added data to a stream! Next you will see how to get data out of the stream.

Step 3: Get the record

GetShardIterator

Before you can get data from the stream, you must obtain the shard iterator for the shard you are interested in. A shard iterator represents the position of the stream and shard from which the consumer (get-record command in this case) will read. You'll use the get-shard-iterator command as follows:

aws kinesis get-shard-iterator --shard-id shardId-000000000000 --shard-iterator-type TRIM_HORIZON --stream-name Foo

Recall that the aws kinesis commands have a Kinesis Data Streams API behind them, so if you are curious about any of the parameters shown, you can read about them in the GetShardIterator API reference topic. Successful execution will result in output similar to the following example:

{
    "ShardIterator": "AAAAAAAAAAHSywljv0zEgPX4NyKdZ5wryMzP9yALs8NeKbUjp1IxtZs1Sp+KEd9I6AJ9ZG4lNR1EMi+9Md/nHvtLyxpfhEzYvkTZ4D9DQVz/mBYWRO6OTZRKnW9gd+efGN2aHFdkH1rJl4BL9Wyrk+ghYG22D2T1Da2EyNSH1+LAbK33gQweTJADBdyMwlo5r6PqcP2dzhg="
}

The long string of seemingly random characters is the shard iterator (yours will be different). You must copy/paste the shard iterator into the get command, shown next. Shard iterators have a valid lifetime of 300 seconds, which should be enough time for you to copy/paste the shard iterator into the next command. You must remove any newlines from your shard iterator before pasting to the next command. If you get an error message that the shard iterator is no longer valid, run the get-shard-iterator command again.

GetRecords

The get-records command gets data from the stream, and it resolves to a call to GetRecords in the Kinesis Data Streams API. The shard iterator specifies the position in the shard from which you want to start reading data records sequentially. If there are no records available in the portion of the shard that the iterator points to, GetRecords returns an empty list. It might take multiple calls to get to a portion of the shard that contains records.

In the following example of the get-records command:

aws kinesis get-records --shard-iterator AAAAAAAAAAHSywljv0zEgPX4NyKdZ5wryMzP9yALs8NeKbUjp1IxtZs1Sp+KEd9I6AJ9ZG4lNR1EMi+9Md/nHvtLyxpfhEzYvkTZ4D9DQVz/mBYWRO6OTZRKnW9gd+efGN2aHFdkH1rJl4BL9Wyrk+ghYG22D2T1Da2EyNSH1+LAbK33gQweTJADBdyMwlo5r6PqcP2dzhg=

If you are running this tutorial from a Unix-type command processor such as bash, you can automate the acquisition of the shard iterator using a nested command, like this:

SHARD_ITERATOR=$(aws kinesis get-shard-iterator --shard-id shardId-000000000000 --shard-iterator-type TRIM_HORIZON --stream-name Foo --query 'ShardIterator')

aws kinesis get-records --shard-iterator $SHARD_ITERATOR

If you are running this tutorial from a system that supports PowerShell, you can automate acquisition of the shard iterator using a command such as this:

aws kinesis get-records --shard-iterator ((aws kinesis get-shard-iterator --shard-id shardId-000000000000 --shard-iterator-type TRIM_HORIZON --stream-name Foo).split('"')[4])

The successful result of the get-records command will request records from your stream for the shard that you specified when you obtained the shard iterator, as in the following example:

{
  "Records":[ {
    "Data":"dGVzdGRhdGE=",
    "PartitionKey":"123”,
    "ApproximateArrivalTimestamp": 1.441215410867E9,
    "SequenceNumber":"49544985256907370027570885864065577703022652638596431874"
  } ],
  "MillisBehindLatest":24000,
  "NextShardIterator":"AAAAAAAAAAEDOW3ugseWPE4503kqN1yN1UaodY8unE0sYslMUmC6lX9hlig5+t4RtZM0/tALfiI4QGjunVgJvQsjxjh2aLyxaAaPr+LaoENQ7eVs4EdYXgKyThTZGPcca2fVXYJWL3yafv9dsDwsYVedI66dbMZFC8rPMWc797zxQkv4pSKvPOZvrUIudb8UkH3VMzx58Is="
}

Note that get-records is described above as a request, which means you may receive zero or more records even if there are records in your stream. Any records returned may not represent all the records currently in your stream. This is normal, and production code will poll the stream for records at appropriate intervals. This polling speed will vary depending on your specific application design requirements.

In your record in this part of the tutorial, you will notice that the data appears to be garbage – and it's not the clear text testdata we sent. This is due to the way put-record uses Base64 encoding to allow you to send binary data. However, the Kinesis Data Streams support in the Amazon CLI does not provide Base64 decoding because Base64 decoding to raw binary content printed to stdout can lead to undesired behavior and potential security issues on certain platforms and terminals. If you use a Base64 decoder (for example, https://www.base64decode.org/) to manually decode dGVzdGRhdGE= you will see that it is, in fact, testdata. This is sufficient for the sake of this tutorial because, in practice, the Amazon CLI is rarely used to consume data. More often, it is used to monitor the state of the stream and obtain information, as shown previously (describe-stream and list-streams). For more information about the KCL, see Developing Custom Consumers with Shared Throughput Using KCL.

get-records doesn't always return all records in the stream/shard specified. When that happens, use the NextShardIterator from the last result to get the next set of records. If more data were being put into the stream, which is the normal situation in production applications, you could keep polling for data using get-records each time. However, if you do not call get-records using the next shard iterator within the 300 second shard iterator lifetime, you will get an error message, and you must use the get-shard-iterator command to get a fresh shard iterator.

Also provided in this output is MillisBehindLatest, which is the number of milliseconds the GetRecords operation's response is from the tip of the stream, indicating how far behind current time the consumer is. A value of zero indicates record processing is caught up, and there are no new records to process at this moment. In the case of this tutorial, you may see a number that's quite large if you've been taking time to read along as you go. By default, data records stay in a stream for 24 hours waiting for you to retrieve them. This time frame is called the retention period and it is configurable up to 365 days.

A successful get-records result will always have a NextShardIterator even if there are no more records currently in the stream. This is a polling model that assumes a producer is potentially putting more records into the stream at any given time. Although you can write your own polling routines, if you use the previously mentioned KCL for developing consumer applications, this polling is taken care of for you.

If you call get-records until there are no more records in the stream and shard you are pulling from, you will see output with empty records similar to the following example:

{
    "Records": [],
    "NextShardIterator": "AAAAAAAAAAGCJ5jzQNjmdhO6B/YDIDE56jmZmrmMA/r1WjoHXC/kPJXc1rckt3TFL55dENfe5meNgdkyCRpUPGzJpMgYHaJ53C3nCAjQ6s7ZupjXeJGoUFs5oCuFwhP+Wul/EhyNeSs5DYXLSSC5XCapmCAYGFjYER69QSdQjxMmBPE/hiybFDi5qtkT6/PsZNz6kFoqtDk="
}

Step 4: Clean up

Delete your stream to free up resources and avoid unintended charges to your account. Do this any time you have created a stream and will not be using it, because charges accrue per stream whether you are putting and getting data with it or not. The clean-up command is as follows:

aws kinesis delete-stream --stream-name Foo

Success results in no output. Use describe-stream to check on the deletion progress:

aws kinesis describe-stream-summary --stream-name Foo

If you execute this command immediately after the delete command, you will see output similar to the following example:

{
    "StreamDescriptionSummary": {
        "StreamName": "samplestream",
        "StreamARN": "arn:aws:kinesis:us-west-2:123456789012:stream/samplestream",
        "StreamStatus": "ACTIVE",

After the stream is fully deleted, describe-stream will result in a "not found" error:

A client error (ResourceNotFoundException) occurred when calling the DescribeStreamSummary operation: 
Stream Foo under account 123456789012 not found.