---
id: snapshot-restore-py
version: "1.0.0"
license: Apache License 2.0
license_treatment: permissive
maintenance: dormant
---

# snapshot-restore-py — Runtime Hooks for AWS Lambda SnapStart - Python

License: permissive · Maintenance: dormant · Downloads: 2.7M/mo

## What it is and what it does

Snapshot Restore for Python is a lightweight library that lets you hook into AWS Lambda's SnapStart lifecycle by registering code to run before a snapshot is captured and after it is restored. It provides two decorators (`@register_before_snapshot` and `@register_after_restore`) and corresponding function-based registration methods to control initialization and cleanup around snapshot boundaries. The library has no runtime dependencies and is already bundled in Lambda runtime environments, making it a zero-friction addition to SnapStart-enabled functions.

The main use case is optimizing Lambda cold starts by deferring expensive initialization (database connections, external API calls, resource setup) until after a snapshot is restored, rather than on every invocation. BeforeSnapshot hooks run in reverse registration order; AfterRestore hooks run in registration order. Hooks must be registered at module level to be recognized; registering them inside the handler or in unimported files will be silently ignored.

Use it for:

- Initialize database connections or connection pools after snapshot restore to avoid stale connections.
- Warm up external API clients or SDKs after restore to ensure fresh authentication and state.
- Clean up temporary resources or close file handles before snapshot to prevent state corruption.
- Establish logging or monitoring context after restore for accurate request tracing.
- Reload configuration or environment-specific settings after restore in multi-environment deployments.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Registers runtime hooks in AWS Lambda SnapStart-enabled Python functions to execute code before snapshots are taken and after snapshots are restored.

Yes, if you are using AWS Lambda SnapStart with Python. The library is already pre-installed in Lambda runtimes, so you only need to add it to local development dependencies for testing. It has no external dependencies, a permissive license, and solves a specific optimization problem. Maintenance is dormant but the API is stable and the scope is narrow, so active updates are not critical.

## Install

pip install snapshot-restore-py
uv add snapshot-restore-py
poetry add snapshot-restore-py

## Installing snapshot-restore-py

Before you install: Low friction: pure Python wheel with no runtime dependencies. Dormant maintenance status (last commit 2024-11-18, no updates since initial release 2024-11-13), but the library is pre-installed in AWS Lambda runtime environments, so local installation is primarily for development and testing.

License in practice: Apache License 2.0 (permissive) allows commercial use, modification, and distribution with minimal restrictions—suitable for most projects.

Quickstart:

from snapshot_restore_py import register_before_snapshot, register_after_restore

@register_before_snapshot
def setup():
    # initialization code
    pass

@register_after_restore
def restore():
    # post-restore code
    pass

Requires Python 3.9+. Hooks registered in files not imported at the top level of your Lambda handler will be ignored; ensure all hook imports occur before lambda_handler execution.

Verify before relying:

- Whether the pre-installed version in Lambda runtime matches the PyPI release version and how version mismatches are handled.
- Performance impact of hook registration and execution order on Lambda cold-start times.
- Compatibility with Lambda extensions or other SnapStart-related tooling.

## Package facts

- License: Apache License 2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: dormant
- Downloads: 2.7M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

aws lambda snapstart hooks, lambda snapshot restore python, runtime hooks lambda, before snapshot after restore, lambda snapstart decorator, aws lambda initialization hooks, lambda cold start optimization, aws-lambda, snapstart, serverless

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