I'm trying to start localstack in a containerized Jenkins build agent for unit testing. In other words, trying to start the localstack docker container from within a docker container. We do this all the time with other images, using the method of mounting `/var/run/docker.sock` in the "parent" container, but localstack will not start.

I get this error:

```
2019-11-08T18:53:53:ERROR:localstack.services.generic_proxy: Exception running proxy on port 8081: [Errno 13] Permission denied: '/tmp/localstack/server.test.pem' Traceback (most recent call last):
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 384, in run_cmd
    combined_file, cert_file_name, key_file_name = GenericProxy.create_ssl_cert(serial_number=self.port)
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 401, in create_ssl_cert
    return generate_ssl_cert(SERVER_CERT_PEM_FILE, serial_number=serial_number)
  File "/opt/code/localstack/localstack/utils/common.py", line 828, in generate_ssl_cert
    save_file(target_file, file_content)
  File "/opt/code/localstack/localstack/utils/common.py", line 642, in save_file
    with open(file, mode) as f:
PermissionError: [Errno 13] Permission denied: '/tmp/localstack/server.test.pem'
```

Port 8081 is not already in use, and `/tmp/localstack` is writable, so I don't understand why it's getting permission denied.
return json.loads(json.dumps(item))
def remove_non_ascii(text):
    
    text = text.decode('utf-8', CODEC_HANDLER_UNDERSCORE)
    
    text = text.encode('ascii', CODEC_HANDLER_UNDERSCORE)
    return text
class NetrcBypassAuth(requests.auth.AuthBase):
    def __call__(self, r):
        return r
class _RequestsSafe(type):
    """ Wrapper around requests library, which can prevent it from verifying
    SSL certificates or reading credentials from ~/.netrc file """
    verify_ssl = True
    def __getattr__(self, name):
        method = requests.__dict__.get(name.lower())
        if not method:
            return method
        def _wrapper(*args, **kwargs):
            if 'auth' not in kwargs:
                kwargs['auth'] = NetrcBypassAuth()
            if not self.verify_ssl and args[0].startswith('https://') and 'verify' not in kwargs:
                kwargs['verify'] = False
            return method(*args, **kwargs)
        return _wrapper
class safe_requests(with_metaclass(_RequestsSafe)):