ELB Support / Fix: APIGW v2 cookies response

[araki-yzrh]

Issue: #149

Hi.
im added ELB support code and tests.
and support APIGW v2 cookies response

see also: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/lambda-functions.html

ELB has two modes.

• single value header and query mode (default)
• multi value header and query mode

Single Value Mode

request event

{
    "requestContext": {
        "elb": {
            "targetGroupArn": "arn:aws:elasticloadbalancing:region:123456789012:targetgroup/my-target-group/6d0ecf831eec9f09"
        }
    },
    "httpMethod": "GET",
    "path": "/",
    "queryStringParameters": { "myKey": "val1" },
    "headers": {
        "accept": "text/html,application/xhtml+xml",
        "accept-language": "en-US,en;q=0.8",
        "content-type": "text/plain",
        "cookie": "cookies",
        "host": "lambda-846800462-us-east-2.elb.amazonaws.com",
        "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6)",
        "x-amzn-trace-id": "Root=1-5bdb40ca-556d8b0c50dc66f0511bf520",
        "x-forwarded-for": "72.21.198.66",
        "x-forwarded-port": "443",
        "x-forwarded-proto": "https"
    },
    "isBase64Encoded": false,
    "body": "request_body"
}

response object

{
    "isBase64Encoded": false,
    "statusCode": 200,
    "statusDescription": "200 OK",
    "headers": {
        "Set-cookie": "cookies",
        "Content-Type": "application/json"
    },
    "body": "Hello from Lambda (optional)"
}

Multi Value Mode

request event

{
    "requestContext": {
        "elb": {
            "targetGroupArn": "arn:aws:elasticloadbalancing:region:123456789012:targetgroup/my-target-group/6d0ecf831eec9f09"
        }
    },
    "httpMethod": "GET",
    "path": "/",
    "multiValueQueryStringParameters": { "myKey": ["val1", "val2"] },
    "multiValueHeaders": {
        "accept": ["text/html,application/xhtml+xml"],
        "accept-language": ["en-US,en;q=0.8"],
        "content-type": ["text/plain"],
        "cookie": ["cookies"],
        "host": ["lambda-846800462-us-east-2.elb.amazonaws.com"],
        "user-agent": ["Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6)"],
        "x-amzn-trace-id": ["Root=1-5bdb40ca-556d8b0c50dc66f0511bf520"],
        "x-forwarded-for": ["72.21.198.66"],
        "x-forwarded-port": ["443"],
        "x-forwarded-proto": ["https"]
    },
    "isBase64Encoded": false,
    "body": "request_body"
}

response object

{
    "isBase64Encoded": false,
    "statusCode": 200,
    "statusDescription": "200 OK",
    "multiValueHeaders": {
        "Set-cookie": ["cookies"],
        "Content-Type": ["application/json"]
    },
    "body": "Hello from Lambda (optional)"
}

Support APIGW v2 cookies response

see also: https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html

response object

{
    "cookies" : ["cookie1", "cookie2"],
    "isBase64Encoded": true|false,
    "statusCode": httpStatusCode,
    "headers": { "headerName": "headerValue", ... },
    "body": "Hello from Lambda!"
}

[jordaneremieff]

Hi @araki-yzrh, thanks for the PR! I'll try to get to reviewing this soon and update the PR with any comments.

[jordaneremieff]

Hey @araki-yzrh! Sorry, my review has been a bit delayed, it might be a bit longer before I'm able to look this over. My personal life has been pretty demanding lately, but I do intend to review this when I find some good time.

[nathanglover]

Anecdotally I can say this PR works as expected. I recently installed this fork of Mangum for a POC deploying Django on AWS lambda using ELB as the trigger and things seem to be working as expected.

Thank you @araki-yzrh and @jordaneremieff for working on this!

[gmachado-nextreason]

Worked here too. Installed the Mangum fork on FastAPI as dependency and deployed to AWS Lambda using ELB.
Any updates on the review? Glad to help if needed.

Thanks for the fork work.

[jordaneremieff]

@araki-yzrh great work, thanks!