Invoking lambda function manually simulating S3 ObjectCreated event trigger? (php aws sdk) - amazon-s3

Question

We had a third party create a python based image thumbnail script that we set up to trigger on an S3 ObjectCreated event. We then imported a collection of close to 5,000 images after testing the script, but the sheer volume of the image files ended up filling up the lambda test space during the import and only about 12% of the images ended up having thumbnails created for them.
We need to manually create thumbnails for the other 88%. While I have a php based script I can run from EC2, it's somewhat slow. It occurs to me that I could create them 'on demand' and could avoid having to create thumbnails for all of the files that didn't auto-create already during the import.
Some of the files may never be accessed again by a customer - the existing lambda thumbnailer already has a slight delay that I account for in the javascript setTimeout retry loop, but before invoking this loop, I could conceivably check if it's a recent upload -- e.g. within the last 10 seconds -- whenever a thumbnail is not found then trigger the lambda manually before starting the retry loop.
But to do this, I need to have the ability to trigger the Lambda script with the parameters similar to the event trigger. It appears as though their script is only accessing the bucket name and key from the event values:
bucket = event['Records'][0]['s3']['bucket']['name']
key = urllib.parse.unquote_plus(event['Records'][0]['s3']['object']['key'], encoding='utf-8')
Being unfamiliar with lambda and still somewhat new to the sdk, I am not sure how I do a lambda trigger that would include those values for the python script.
I can use either the php sdk or the javascript sdk. (or even the cli)
Any help is appreciated.

Answer 1

I think I figured it out, copying the data structure in the python references to create a bare-bones payload and triggering it as event:
$lambda = $awsSvc->getAwsSdkCached()->createLambda();
// bucket = event['Records'][0]['s3']['bucket']['name']
// key = urllib.parse.unquote_plus(event['Records'][0]['s3']['object']['key'], encoding='utf-8')
$bucket = "mybucket";
$key = "somefolder/someimage.jpg";
$payload_json = sprintf('{"Records":[{"s3":{"bucket":{"name":"%s"},"object":{"key":"%s"}}}]}', $bucket, $key);
$params = array(
'FunctionName' => 'ThumbnailGenerator',
'InvocationType' => 'Event',
'LogType' => 'Tail',
'Payload' => $payload_json
);
$result = $lambda->invoke($params);