Add Lambda Durable Functions with Human-in-the-Loop pattern

lambda-durable-hitl-python-sam/.gitignore

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+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# Virtual environments
+venv/
+ENV/
+env/
+.venv
+
+# Testing
+.pytest_cache/
+.coverage
+htmlcov/
+.hypothesis/
+*.cover
+.tox/
+
+# IDEs
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# AWS SAM
+.aws-sam/
+samconfig.toml
+
+# Logs
+*.log
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Environment variables
+.env
+.env.local

lambda-durable-hitl-python-sam/example-pattern.json

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+{
+  "title": "Lambda Durable Functions with Human-in-the-Loop",
+  "description": "Demonstrates Lambda durable functions with human approval workflow using Python 3.13, DynamoDB, and SNS",
+  "language": "Python",
+  "level": "300",
+  "framework": "SAM",
+  "introBox": {
+    "headline": "How it works",
+    "text": [
+      "This pattern demonstrates how to pause Lambda execution, wait for human approval, and resume using the Lambda durable functions SDK.",
+      "The Workflow Lambda creates an approval request in DynamoDB and polls for decisions using durable waits (no compute charges during waits).",
+      "An SNS notification is sent to approvers, who can submit their decision via the Approval API Lambda function.",
+      "The Workflow Lambda detects the decision during polling and resumes execution with the approval result.",
+      "The pattern includes timeout handling, status tracking, and a complete audit trail of all approval decisions."
+    ]
+  },
+  "gitHub": {
+    "template": {
+      "repoURL": "https://github.com/aws-samples/serverless-patterns/tree/main/lambda-durable-hitl-python-sam",
+      "templateURL": "serverless-patterns/lambda-durable-hitl-python-sam",
+      "projectFolder": "lambda-durable-hitl-python-sam",
+      "templateFile": "template.yaml"
+    }
+  },
+  "resources": {
+    "bullets": [
+      {
+        "text": "Lambda Durable Functions Documentation",
+        "link": "https://docs.aws.amazon.com/lambda/latest/dg/durable-functions.html"
+      },
+      {
+        "text": "AWS SAM Documentation",
+        "link": "https://docs.aws.amazon.com/serverless-application-model/"
+      },
+      {
+        "text": "DynamoDB Best Practices",
+        "link": "https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/best-practices.html"
+      },
+      {
+        "text": "Amazon SNS Documentation",
+        "link": "https://docs.aws.amazon.com/sns/"
+      }
+    ]
+  },
+  "deploy": {
+    "text": [
+      "sam build",
+      "sam deploy --guided"
+    ]
+  },
+  "testing": {
+    "text": [
+      "See the README in the GitHub repo for detailed testing instructions.",
+      "Test the approval workflow using AWS CLI:",
+      "1. Publish Lambda version: aws lambda publish-version --function-name <WorkflowFunction>",
+      "2. Invoke workflow: aws lambda invoke --function-name <WorkflowFunction>:<version> --invocation-type Event --payload '{...}' response.json",
+      "3. List approvals: aws dynamodb scan --table-name <ApprovalsTable>",
+      "4. Submit decision: aws lambda invoke --function-name <ApprovalApiFunction> --payload '{\"action\":\"decide\",...}' response.json"
+    ]
+  },
+  "cleanup": {
+    "text": [
+      "Delete the stack: sam delete"
+    ]
+  },
+  "authors": [
+    {
+      "name": "Mian Tariq",
+      "bio": "Cloud Solutions Architect"
+    }
+  ],
+  "patternArch": {
+    "icon1": {
+      "name": "lambda",
+      "label": "Lambda Durable Functions"
+    },
+    "icon2": {
+      "name": "dynamodb",
+      "label": "Amazon DynamoDB"
+    },
+    "icon3": {
+      "name": "sns",
+      "label": "Amazon SNS"
+    }
+  }
+}

lambda-durable-hitl-python-sam/src/approval_api/Dockerfile

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+FROM public.ecr.aws/lambda/python:3.13
+
+# Copy requirements file
+COPY approval_api/requirements.txt ${LAMBDA_TASK_ROOT}/
+
+# Install dependencies
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy function code
+COPY approval_api/app.py ${LAMBDA_TASK_ROOT}/
+COPY shared/*.py ${LAMBDA_TASK_ROOT}/
+
+# Set the CMD to your handler
+CMD ["app.lambda_handler"]