Add Lambda bundled runtime useragent header

[nvasiu]

• Add boolean that checks if the SDK is running in a path that matches the path used within the Lambda bundled runtime.
• Update the useragent header string to include "-bundledruntime" if the above boolean is true.

Issue #, if available:

N/A

Description of changes:

Note: we are waiting to confirm the Lambda bundled runtime SDK path. Do NOT merge this PR until we get confirmation.

Updating the UserAgent header string to indicate whether the SDK is being run within the Lambda bundled runtime.

• A new boolean checks if the SDK's current path matches the path where it would be installed in the Lambda bundled runtime.
• If the above boolean is true, the string inserted into the UserAgent header will include "-bundled". Example:
  aws-durable-execution-sdk-python/{version}-bundled

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[zhongkechen]

should this -bundledruntime be part of the sdk name or part of the version?

And -bundledruntime sounds weird like the runtime is bundled in SDK. Why don't we simply used -bundled?

[nvasiu]

I think it makes sense as part of the name, because the bundled runtime doesn't use a special SDK version.

I can make an update to just say "-bundled".

[leandrodamascena]

Sorry to jump into the conversation, but I would add the AWS_EXECUTION_ENV environment variable here - if not set assume "NA" for example. While this SDK is 100% focused on Lambda and only works with the specific payload sent to Lambda, you never know how creatively customers are using it. In Powertools for AWS Lambda, we identified clients using it on a wide variety of platforms other than Lambda.

But of course, it's just an idea, and I don't know if this affects how you consume this string in the backend.

[yaythomas]

agree re the bundling effectively being a version variant. something like aws-durable-execution-sdk-python/v.1.2.3-bundled

[yaythomas]

re AWS_EXECUTION_ENV

if exists could be:

# bring your own
aws-durable-execution-sdk-js/1.2.3#nodejs24.x

# bundled
aws-durable-execution-sdk-js/1.2.3-bundled#runtime-nodejs24.x

# no execution env variable, use current interpreter version
aws-durable-execution-sdk-js/1.2.3-bundled#node-v20.19.0

[yaythomas]

should this be /var/lang/?

/var/langsurprise/ will return true here.

also, os.path.dirname isn't adding much here, might as well just use __file__.startswith("/var/lang/")

[yaythomas]

also, var name should prob be _IS_IN_VAR_DIR.

but the __file__ lookup is also just a lookup in the global namespace, so at the module level this isn't winning much, might as well have the check in the initialize check and then unit test on the actual file name too.

   def _is_in_var_dir(module_file: str = __file__) -> bool:
       """Return True if this SDK is installed under /var/lang/.

       Lambda BYOL Python runtimes install bundled packages at
       /var/lang/lib/pythonX.Y/site-packages/ 
       """
       return module_file.startswith("/var/lang/")

[yaythomas]

does this actually do anything? there aren't any env vars under test?

[yaythomas]

Reference: the similar change in ts/js aws/aws-durable-execution-sdk-js#527

made changes myself

[bchampp]

I feel like -runtime might be more accurate (since it's bundled in the runtime)