snapshot-restore-py

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 on this page — 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

snapshot-restore-py on PyPI

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

Evidence: snapshot_restore_py-1.0.0-py3-none-any.whl

Keywords: serverless, aws, lambda, python, snapstart, runtime, hooks

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