# 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}"
```
has_been_invoked_before = func_arn in self.function_invoke_times
        
        with self.docker_container_lock:
            env_vars['_LAMBDA_SERVER_PORT'] = str(self.next_port + self.port_offset)
            self.next_port = (self.next_port + 1) % self.max_port
        
        LOG.debug('Priming docker container with runtime "%s" and arn "%s".', runtime, func_arn)
        container_info = self.prime_docker_container(runtime, func_arn, env_vars.items(), lambda_cwd)
        
        
        
        exec_env_vars = ' '.join(['-e {}="${}"'.format(k, k) for (k, v) in env_vars.items()])
        if not command:
            command = '%s %s' % (container_info.entry_point, handler)
        
        copy_command = ''
        docker_cmd = self._docker_cmd()
        if not has_been_invoked_before and config.LAMBDA_REMOTE_DOCKER:
            
            copy_command = '%s cp "%s/." "%s:/var/task";' % (docker_cmd, lambda_cwd, container_info.name)
        cmd = (
            '%s'
            ' %s exec'
            ' %s'  
            ' %s'  
            ' %s'  
        ) % (copy_command, docker_cmd, exec_env_vars, container_info.name, command)
        LOG.debug('Command for docker-reuse Lambda executor: %s' % cmd)
        return cmd
    def startup(self):