# Type of request: This is a ...

[*] bug report
[ ] feature request

# Detailed description

Perhaps not a bug report per se, but this affected me at least. A new version of `lambci/docker-lambda` was pushed recently. [This commit](https://github.com/lambci/docker-lambda/commit/7ece2742a5b0e84eb09d6ed659f123474e619b27) removed hardcoded defaults for `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`.

I have a lambda that reads a value from secret in `secretsmanager`. If I don't set dummy values for `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` when creating the lambda invoking it will time out reading the secret.

## Expected behavior

A lambda function can read a secret from `secretsmanager`.

## Actual behavior

Lambda times out trying to read secret.

# Steps to reproduce

Create a lambda which tries to read a secret from `secretsmanager` without adding the environments variables mentioned above.

## Command used to start LocalStack

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

This will work:
```bash
awslocal lambda create-function \
  --function-name foo \
  --runtime go1.x \
  --handler main \
  --role arn:aws:iam::123456790:role/ignore \
  --zip-file fileb://foo.zip \
  --environment "Variables={FOO=bar,AWS_ACCOUNT_ID=123456790,AWS_ACCESS_KEY_ID=0,AWS_SECRET_ACCESS_KEY=0}"
```

This will time out while reading:
```bash
awslocal lambda create-function \
  --function-name foo \
  --runtime go1.x \
  --handler main \
  --role arn:aws:iam::123456790:role/ignore \
  --zip-file fileb://foo.zip \
  --environment "Variables={FOO=bar}"
```
super(LambdaExecutorSeparateContainers, self).__init__()
        self.next_port = 1
        self.max_port = LAMBDA_API_UNIQUE_PORTS
        self.port_offset = LAMBDA_API_PORT_OFFSET
    def prepare_event(self, environment, event_body):
        
        environment['DOCKER_LAMBDA_USE_STDIN'] = '1'
        return event_body.encode()
    def prepare_execution(self, func_arn, env_vars, runtime, command, handler, lambda_cwd):
        entrypoint = ''
        if command:
            entrypoint = ' --entrypoint ""'
        else:
            command = '"%s"' % handler
        
        network = config.LAMBDA_DOCKER_NETWORK
        network_str = '--network="%s"' % network if network else ''
        if network == 'host':
            port = str(self.next_port + self.port_offset)
            env_vars['DOCKER_LAMBDA_API_PORT'] = port
            env_vars['DOCKER_LAMBDA_RUNTIME_PORT'] = port
            self.next_port = (self.next_port + 1) % self.max_port
        env_vars_string = ' '.join(['-e {}="${}"'.format(k, k) for (k, v) in env_vars.items()])