A way to locally run AWS Lambda functions (#4128)

This gives us a way to locally run and test our AWS Lambda integration,
without needing a real AWS Lambda account.

This should make development of AWS Lambda support better.

---------

Co-authored-by: Ivana Kellyer <[email protected]>

Author: antonpirker

scripts/test-lambda-locally/.gitignore

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+.envrc
+.venv/
+package/
+lambda_deployment_package.zip

scripts/test-lambda-locally/README.md

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+# Test AWS Lambda functions locally
+
+An easy way to run an AWS Lambda function with the Sentry SDK locally. 
+
+This is a small helper to create a AWS Lambda function that includes the 
+currently checked out Sentry SDK and runs it in a local AWS Lambda environment.
+
+Currently only embedding the Sentry SDK into the Lambda function package 
+is supported. Adding the SDK as Lambda Layer is not possible at the moment. 
+
+## Prerequisites
+
+- Set `SENTRY_DSN` environment variable. The Lambda function will use this DSN.
+- You need to have Docker installed and running. 
+
+## Run Lambda function
+
+- Update `lambda_function.py` to include your test code. 
+- Run `./deploy-lambda-locally.sh`. This will:
+    - Install [AWS SAM](https://aws.amazon.com/serverless/sam/) in a virtual Python environment
+    - Create a lambda function package in `package/` that includes
+        - The currently checked out Sentry SDK
+        - All dependencies of the Sentry SDK (certifi and urllib3)
+        - The actual function defined in `lamdba_function.py`. 
+    - Zip everything together into lambda_deployment_package.zip
+    - Run a local Lambda environment that serves that Lambda function.
+- Point your browser to `http://127.0.0.1:3000` to access your Lambda function.
+    - Currently GET and POST requests are possible. This is defined in `template.yaml`.

scripts/test-lambda-locally/deploy-lambda-locally.sh

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+#!/usr/bin/env bash
+
+# exit on first error
+set -xeuo pipefail
+
+# Setup local AWS Lambda environment
+
+# Install uv if it's not installed
+if ! command -v uv &> /dev/null; then
+    curl -LsSf https://astral.sh/uv/install.sh | sh
+fi
+
+uv sync
+
+# Create a deployment package of the lambda function in `lambda_function.py`.
+rm -rf package && mkdir -p package              
+pip install ../../../sentry-python -t package/ --upgrade
+cp lambda_function.py package/ 
+cd package && zip -r ../lambda_deployment_package.zip . && cd ..
+
+# Start the local Lambda server with the new function (defined in template.yaml)
+uv run sam local start-api \
+    --skip-pull-image \
+    --force-image-build \
+    --parameter-overrides SentryDsn=$SENTRY_DSN

scripts/test-lambda-locally/lambda_function.py

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+import logging
+import os
+import sentry_sdk
+
+from sentry_sdk.integrations.aws_lambda import AwsLambdaIntegration
+from sentry_sdk.integrations.logging import LoggingIntegration
+
+def lambda_handler(event, context):
+    sentry_sdk.init(
+        dsn=os.environ.get("SENTRY_DSN"),
+        attach_stacktrace=True,
+        integrations=[
+            LoggingIntegration(level=logging.INFO, event_level=logging.ERROR),
+            AwsLambdaIntegration(timeout_warning=True)
+        ],
+        traces_sample_rate=1.0,
+        debug=True,
+    )
+
+    try:
+        my_dict = {"a" : "test"}
+        value = my_dict["b"] # This should raise exception
+    except:
+        logging.exception("Key Does not Exists")
+        raise

scripts/test-lambda-locally/pyproject.toml

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+[project]
+name = "test-lambda-locally"
+version = "0"
+requires-python = ">=3.12"
+
+dependencies = [
+    "aws-sam-cli>=1.135.0",
+]

scripts/test-lambda-locally/template.yaml

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+AWSTemplateFormatVersion: '2010-09-09'
+Transform: AWS::Serverless-2016-10-31
+Resources:
+  SentryLambdaFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      CodeUri: lambda_deployment_package.zip
+      Handler: lambda_function.lambda_handler
+      Runtime: python3.12
+      Timeout: 30
+      Environment:
+        Variables:
+          SENTRY_DSN: !Ref SentryDsn
+      Events:
+        ApiEventGet:
+          Type: Api
+          Properties:
+            Path: /
+            Method: get
+        ApiEventPost:
+          Type: Api
+          Properties:
+            Path: /
+            Method: post
+
+Parameters:
+  SentryDsn:
+    Type: String
+    Default: ''