def get_env_var(name: str) -> str:
env_var = os.getenv(name)
if env_var is None:
error_message = f'{name} Enviroment Variable is missing for this lambda'
logger.error(error_message)
raise Exception(error_message)
return env_var
def create_presigned_post(bucket_name,
object_name,
fields=None,
conditions=None,
expiration=3600):
"""Generate a presigned URL S3 POST request to upload a file
:param bucket_name: string
:param object_name: string
:param fields: Dictionary of prefilled form fields
:param conditions: List of conditions to include in the policy
:param expiration: Time in seconds for the presigned URL to remain valid
:return: Dictionary with the following keys:
url: URL to post to
fields: Dictionary of form fields and values to submit with the POST
:return: None if error.
"""
# Generate a presigned S3 POST URL
s3_client = boto3.client('s3')
try:
response = s3_client.generate_presigned_post(bucket_name,
object_name,
Fields=fields,
Conditions=conditions,
ExpiresIn=expiration)
except ClientError as e:
logger.error(e)
return None
# The response contains the presigned URL and required fields
return response
def _build_error_response(err,
status: HTTPStatus = HTTPStatus.INTERNAL_SERVER_ERROR
) -> dict:
logger.error(str(err))
return {
'statusCode': status,
'headers': {
'Content-Type': 'application/json'
},
'body': str(err),
}
def upload_s3_object_presigned(source_file: str, object_name: str,
bucket_name: str) -> str:
response = create_presigned_post(bucket_name, object_name)
if response is None:
raise Exception(
"Error generating presigned url for {object_name=}, {bucket_name=}"
)
with open(source_file, 'rb') as f:
files = {'file': (object_name, f)}
http_response = requests.post(response['url'],
data=response['fields'],
files=files)
# If successful, returns HTTP status code 204
logger.info(f'File upload HTTP status code: {http_response.status_code}')
if http_response.status_code > 300:
logger.error(
f"Error uploading object with presigned url {http_response.content=}"
)
raise Exception(f"Error uploading {object_name=} to {bucket_name=}")