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# Copyright Andrew Jorgensen | |
# SPDX-License-Identifier: MIT | |
"""Receive SNS events in Lambda and POST to a JSON Webhook. | |
Environment variables required: | |
* URL - The Webhook URL to POST to (including any required keys) | |
* TEMPLATE (default: {}) - The JSON data template to POST to the Webhook | |
* MESSAGE_KEY (default: text) - Key to set to the SNS Message | |
* TOPIC_KEY (optional) - Key to set to the Topic name from the SNS event | |
""" | |
import json | |
from os import environ | |
from urllib.request import urlopen, Request | |
CONTENT_TYPE = "application/json; charset=utf-8" | |
PREFIX = environ.get("ENV_PREFIX", "") | |
URL = environ.get(PREFIX + "URL") | |
TEMPLATE = environ.get(PREFIX + "TEMPLATE", "{}") | |
MESSAGE_KEY = environ.get(PREFIX + "MESSAGE_KEY", "text") | |
TOPIC_KEY = environ.get(PREFIX + "TOPIC_KEY") | |
def lambda_handler(event, context): | |
"""Lambda handler - expects an SNS event""" | |
user_agent = context.function_name | |
print(json.dumps(event)) | |
topic = event["Records"][0]["Sns"]["TopicArn"].rsplit(":", 1)[1] | |
subject = event["Records"][0]["Sns"]["Subject"] | |
message = event["Records"][0]["Sns"]["Message"] | |
# Pretty-print if the message is JSON | |
try: | |
message = json.dumps(json.loads(message), indent=4) | |
except json.decoder.JSONDecodeError: | |
pass | |
data = json.loads(TEMPLATE) | |
if TOPIC_KEY: | |
data[TOPIC_KEY] = topic | |
if subject: | |
data[MESSAGE_KEY] = f"{subject}: {message}" | |
else: | |
data[MESSAGE_KEY] = message | |
data = json.dumps(data, sort_keys=True) | |
print(data) | |
request = Request( | |
url=URL, | |
data=data.encode("utf-8"), | |
headers={"User-Agent": user_agent, "Content-Type": CONTENT_TYPE}, | |
) | |
with urlopen(request) as response: | |
if response.getheader("content-type").split(";")[0] == "application/json": | |
# Round-trip the response to clean it up for the log | |
print(json.dumps(json.load(response))) | |
else: | |
print(response.read().decode("utf-8")) |
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