Adding custom headers to all boto3 requests - http-headers

Question

I need to add some custom headers to every boto3 request that is sent out. Is there a way to manage the connection itself to add these headers?
For boto2, connection.AWSAuthConnection has a method build_base_http_request which has been helpful. I've yet to find an analogous function within the boto3 documentation though.

Answer 1

This is pretty dated but we encountered the same issue, so I'm posting our solution.
I wanted to add custom headers to boto3 for specific requests.
I found this: https://github.com/boto/boto3/issues/2251, and used the event system for adding the header
def _add_header(request, **kwargs):
request.headers.add_header('x-trace-id', 'trace-trace')
print(request.headers) # for debug
some_client = boto3.client(service_name=SERVICE_NAME)
event_system = some_client.meta.events
event_system.register_first('before-sign.EVENT_NAME.*', _add_header)
You can try using a wildcard for all requests:
event_system.register_first('before-sign.*.*', _add_header)
*SERVICE_NAME- you can find all available services here: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/index.html
For more information about register a function to a specific event: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/events.html

Answer 2

Answer from #May Yaari is pretty awesome. To the concern raised by #arainchi:
This works, there is no way to pass custom data to event handlers, currently we have to do it in a non-pythonic way using global variables/queues :( I have opened issue ticket with Boto3 developers for this exact case
Actually, we could leverage the python functional programming property: returning a function inside a function to get around:
In the case we want to add a custom value custom_variable to the header, we could do
some_client = boto3.client(service_name=SERVICE_NAME)
event_system = some_client.meta.events
event_system.register_first('before-sign.EVENT_NAME.*', _register_callback(custom_variable))
def _register_callback(custom_variable):
def _add_header(request, **kwargs):
request.headers.add_header('header_name_you_want', custom_variable)
return _add_header
Or a more pythonic way using lambda
some_client = boto3.client(service_name=SERVICE_NAME)
event_system = some_client.meta.events
event_system.register_first('before-sign.EVENT_NAME.*', lambda request, **kwargs: _add_header(request, custom_variable))
def _add_header(request, custom_variable):
request.headers.add_header('header_name_you_want', custom_variable)