lambda-asyncio 0.0.3
Micro-framework to effectively run asyncio functions in AWS LAMBDA
License: Apache License 2.0

# lambda-asyncio

Safely use asyncio handlers in AWS Lambda functions.

## Installation

Run `pip install lambda-asyncio`, or add it to your package dependencies.

## Usage

### Handler

Define your Lambda handler as an `async` function, and add the `lambda_async_handler`
annotation.

```python
@lambda_async_handler()
async def my_handler(event, context):
    await asyncio.sleep(1)
    return response
```

By default, handlers are *eager*, meaning an event loop will be created and
initialisation functions will be immediately run on module import. This somewhat
matches the behaviour of a synchronous Lambda function with resources as global
module variables.

If you wan to initialise resources only when a handler is first called, do:

```python
@lambda_async_handler(eager=False)
async def my_handler(event, context):
    await asyncio.sleep(1)
    return response
```

### Initialisation

You can define `async` initialization functions to prepare resources for use by
handlers.

These can be simple `async def`s returning nothing:

```python
from lambda_asyncio import lambda_async_init

@lambda_async_init()
async def my_init() -> None:
    print('Hello, world!')
```

Initialization order can be controlled with the `order` parameter:

```python
from lambda_asyncio import lambda_async_init


@lambda_async_init(order=20)
async def world():
    print('World!')

@lambda_async_init(order=10)
async def hello():
    print('Hello!')
```

Or you can use `AsyncContextManagers`, and access the resources they create by
refering to the handler function. Proper lifetime will be managed internally, such
that the initialization will happen once.


```python
import asyncio
from typing import AsyncIterator, Tuple
from asyncio.stream import StreamReader, StreamWriter

import aiofiles
from lambda_asyncio import lambda_async_init, lambda_async_handler

@lambda_async_init()
@asynccontextmanager
async def json_log_file() -> AsyncIterator[]:
    async with aiofiles.open('/tmp/my-file.json', mode='a') as f:
        yield f

@lambda_async_handler()
async def handler(event, context):
    log_file = await json_log_file()
    await log_file.write(json.dumps(event) + ")
    await log_file.
    reader, writer = await connection()
    writer.write('GET / HTTP/1.1\r\n')
    writer.write('Host: google.com\r\n')
    await writer.drain()

    response = await reader.read()
    print(response)
```

# Changelog

<!--next-version-placeholder-->

## v0.0.3 (2022-05-04)
### Fix
* **cd:** Fix long_description Markdown content type ([`b3479ee`](https://github.com/danielkza/lambda-asyncio-py/commit/b3479ee384df19062b09f42f976854ed0608f991))

## v0.0.2 (2022-05-04)
### Fix
* **cd:** Don't release on new tags ([`581d5ff`](https://github.com/danielkza/lambda-asyncio-py/commit/581d5ffc6ec70737841f683e520b77288362df15))

## v0.0.1 (2022-05-04)
### Fix
* **cd:** Force release ([`7bbac93`](https://github.com/danielkza/lambda-asyncio-py/commit/7bbac93ee910d88b4ac3ef9a0ff33c0e19af2bab))
* **cd:** Force release ([`dd9f209`](https://github.com/danielkza/lambda-asyncio-py/commit/dd9f20986552004674a45f229d8a0e2f70188d96))
* **cd:** Force release ([`e621555`](https://github.com/danielkza/lambda-asyncio-py/commit/e6215558d3cbdebf2809c09159f3a1f8d929f33b))


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