pdf2image-lambda

Create images from PDF documents uploaded to S3 buckets.
The images are placed next to the original file with numbered suffixes.

Thanks to Lambda's concurrency, this approach is well-suited to variable bulk/batch higher-volume conversion workloads.
Please double check you are in the AWS region you intend; this needs to be the same region as the bucket which will contain the PDF documents you wish to convert.

Execution Role

Ensure that your execution role has both "s3:GetObject" and "s3:PutObject" permissions on the source buckets.
Without GetObject/PutObject permission on the triggering bucket you will get Access Denied errors.

S3 Trigger

This function responds to S3 ObjectCreated events.

To configure the trigger, on the Lambda function, in "Designer > Add triggers", click "S3". The "Configure triggers" dialog appears. Select a bucket (any time a pdf is added to this bucket, the function will run).
Verify that "all object create events" is selected (or choose PUT POST or COPY).
Click "Add" (bottom right), then "Save" (top right).

Confirm successful installation

S3 Trigger

If you configured the S3 trigger, you can try it, by uploading a PDF document into the S3 bucket you have set the trigger on.
To verify it works, look for image files next to the PDF file, or check the logs in cloudwatch.

Sizing Notes

If you observe "Process exited before completing request" errors, it might point to your lambda function not having sufficient resources or time-out period.

Memory

Experience suggests assigning 2048MB.
This can be set under the "Memory (MB)" header in the "Basic settings" section of the Lambda function configuration tab.

Timeout

The time taken for the Lambda to run, will depend on the size of the PDF document being processed.
For maximum flexibility, allow a 15 minute timeout, although experience suggests that the function should hardly ever take longer than a few seconds to run.

This can be set under the "Timeout" header in the "Basic settings" section of the Lambda function configuration tab.

Image formats

Image type and DPI can be configured in the index.py file.
Supported formats: png, jpeg, tiff, ppm.

CDK config example

// create reference to an existing bucket by name
const bucket = Bucket.fromBucketAttributes(this, 'Bucket', { bucketName: props.s3BucketName });

const pdf2Image = new PythonFunction(this, 'Pdf2Image', {
    functionName: 'pdf2-image',
    description: 'Converts PDF files to imges',
    entry: path.join(__dirname, '..', 'functions', 'pdf2image-lambda'),
    index: 'index.py',
    handler: 'pdf_to_image',
    runtime: Runtime.PYTHON_3_11,
    logRetention: RetentionDays.ONE_WEEK,
    timeout: Duration.seconds(30),
    memorySize: 2048
});

bucket.grantReadWrite(pdf2Image);
// invoke the lambda function each time an object matching the prefix and suffix is created in the referenced bucket
bucket.addEventNotification(EventType.OBJECT_CREATED, new LambdaDestination(pdf2Image), { prefix: 'emails/parsed/', suffix: 'pdf' });