Understanding MaxDocumentSizeExceededException in AWS Simple Systems Management

In the modern cloud landscape, managing systems efficiently is vital for maintaining operational excellence. AWS Simple Systems Management (SSM) offers a powerful suite of tools designed to streamline and automate infrastructure tasks. However, while utilizing the SSM capabilities, developers may encounter the MaxDocumentSizeExceededException. In this article, we will delve into the details of this exception, its causes, best practices for handling it, and relevant code examples.

What is MaxDocumentSizeExceededException?

The MaxDocumentSizeExceededException is an exception thrown by the AWS SSM API, specifically under the com.amazonaws.services.simplesystemsmanagement.model package. It occurs when a document, such as a command or a configuration state, exceeds the maximum size limit permitted by AWS SSM, which currently stands at 64 KB.

This exception indicates that the payload you are trying to send or receive is too large and requires modifications to comply with size restrictions.

Causes of MaxDocumentSizeExceededException

1. Excessively Large Command or Document: Attempting to execute commands or configurations with an overloaded set of scripts, parameters, or data can lead directly to this exception.

2. Improper Encoding: Sending large documents with improper encoding can inadvertently increase their sizes beyond the limit, resulting in failures.

3. Aggregation of Responses: When trying to manage output from multiple instances or aggregating results, it’s easy to surpass the document limits.

How to Handle MaxDocumentSizeExceededException

There are a few strategies you can utilize to avoid the MaxDocumentSizeExceededException:

1. Chunking the Data: Divide your commands or configurations into smaller, manageable chunks. This way, each segment fits within the size limit.

2. Utilizing AWS S3: Instead of sending large payloads through SSM, consider storing the documents in Amazon S3 and referencing them through your SSM command.

3. Optimize Your Commands: Remove unnecessary parts of the scripts or the command documents. Make use of concise and efficient coding techniques.

4. Review Logs and Debugging: Always review your logs for any patterns that may indicate size issues to help diagnose when you’re about to hit a limit.

Code Examples

Submitting a SSM Command and Handling Exceptions

Here’s a Java example that demonstrates how to submit a command while handling the MaxDocumentSizeExceededException:

import com.amazonaws.services.simplesystemsmanagement.AWSSimpleSystemsManagement;
import com.amazonaws.services.simplesystemsmanagement.AWSSimpleSystemsManagementClientBuilder;
import com.amazonaws.services.simplesystemsmanagement.model.SendCommandRequest;
import com.amazonaws.services.simplesystemsmanagement.model.SendCommandResult;
import com.amazonaws.services.simplesystemsmanagement.model.MaxDocumentSizeExceededException;

public class SSMCommandExample {
    private static final int MAX_DOCUMENT_SIZE = 65536; // 64 KB

    public static void main(String[] args) {
        AWSSimpleSystemsManagement ssmClient = AWSSimpleSystemsManagementClientBuilder.defaultClient();
        String commandDocument = ""; // Load your command document

        try {
            if (commandDocument.length() > MAX_DOCUMENT_SIZE) {
                throw new IllegalArgumentException("Command document exceeds the maximum allowed size.");
            }

            SendCommandRequest request = new SendCommandRequest()
                    .withDocumentName("AWS-RunShellScript")
                    .withParameters(Collections.singletonMap("commands", Arrays.asList(commandDocument)))
                    .withTargets(Collections.singletonList(new Target().withKey("instanceids").withValues("i-1234567890abcdef0")));
                      
            SendCommandResult result = ssmClient.sendCommand(request);
            System.out.println("Command ID: " + result.getCommand().getCommandId());
        } catch (MaxDocumentSizeExceededException e) {
            System.err.println("Max Document Size Exceeded: " + e.getMessage());
        } catch (IllegalArgumentException e) {
            System.err.println("Error: " + e.getMessage());
        }
    }
}

Using AWS S3 for Large Documents

Instead of sending large documents directly, you can upload the command to an S3 bucket and invoke it using a reference:

import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.PutObjectRequest;

import java.io.File;

public class S3CommandExample {
    
    public static void main(String[] args) {
        AmazonS3 s3Client = AmazonS3ClientBuilder.defaultClient();
        String bucketName = "your-s3-bucket-name";
        String key = "commands/large-command.sh";
        File scriptFile = new File("path/to/your/large-command.sh");

        // Upload script to S3
        s3Client.putObject(new PutObjectRequest(bucketName, key, scriptFile));
        System.out.println("Uploaded script to S3: " + key);

        // Now use this reference in your SSM command
        // Assume the appropriate logic to run the command referenced in S3 goes here
    }
}

Conclusion

The MaxDocumentSizeExceededException can seem daunting, but by understanding its causes and developing strategies to manage document sizes effectively, you can minimize disruptions in your workflow. By leveraging chunking techniques, utilizing S3 for larger documents, and optimizing your commands, you can maintain consistency and efficiency in your AWS operations.

Always remember to handle exceptions gracefully and review AWS best practices regarding SSM document sizes.

For more information, you can consult the official AWS Documentation and AWS SDK for Java Documentation.

References

• AWS Simple Systems Management Documentation
• Handling Exceptions in AWS SDK for Java
• Amazon S3 Documentation

Make the most of AWS SSM by carefully managing the size of your commands and documents!