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Having upgraded to the latest LocalStack version, I've noticed that Docker containers from Lambda executions are immediately removed when they terminate.

This was added in https://github.com/localstack/localstack/pull/1584

I can appreciate the need to clean up containers, however this feature of having them stay up is actually very useful for debugging things when they go wrong!

Would it be possible to have a flag so that when running LocalStack we can specify whether to remove containers on completion? Something like:

```
services:
  localstack:
    image: localstack/localstack:latest
    ports:
      - "4567-4593:4567-4593"
    environment:
      - SERVICES=serverless,ssm,stepfunctions
      - DOCKER_HOST=unix:///var/run/docker.sock
      - LAMBDA_EXECUTOR=docker
      - REMOVE_CONTAINERS_ON_LAMBDA_TERMINATE=true #(or false)
    volumes:
      - "${TMPDIR:-/tmp/localstack}:/tmp/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
```

Thanks for the great work folks!
bucket_name = normalize_bucket_name(bucket_name)
    cors = BUCKET_CORS.get(bucket_name)
    if not cors:
        return
    origin = request_headers.get('Origin', '')
    rules = cors['CORSConfiguration']['CORSRule']
    if not isinstance(rules, list):
        rules = [rules]
    for rule in rules:
        
        allowed_methods = rule.get('AllowedMethod', [])
        if request_method in allowed_methods:
            allowed_origins = rule.get('AllowedOrigin', [])
            for allowed in allowed_origins:
                if origin in allowed or re.match(allowed.replace('*', '.*'), origin):
                    response.headers['Access-Control-Allow-Origin'] = origin
                    if 'ExposeHeader' in rule:
                        expose_headers = rule['ExposeHeader']
                        response.headers['Access-Control-Expose-Headers'] = \
                            ','.join(expose_headers) if isinstance(expose_headers, list) else expose_headers
                    break
def append_last_modified_headers(response, content=None):