Internal server error when accessing visualization URLs that do not exist

[hackdna]

• Specific code commit: 8d80f47
• Version of the web browser and OS: n/a
• Environment where the error occurred (Vagrant VM and site conf mode or AWS instance): AWS

Steps to reproduce

Access a URL that doesn't exists like /visualizations/asdf/.

Observed behavior

HTTP 500 error:

Internal Server Error: /visualizations/asdf/
Traceback (most recent call last):
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/django/core/handlers/base.py", line 111, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/django_docker_engine/proxy.py", line 50, in _proxy_view
    container_url = DockerClientWrapper().lookup_container_url(container_name)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/django_docker_engine/docker_utils.py", line 98, in lookup_container_url
    return self._containers_manager.get_url(container_name)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/django_docker_engine/container_managers/docker_engine.py", line 41, in get_url
    container = self._containers_client.get(container_name)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/models/containers.py", line 720, in get
    resp = self.client.api.inspect_container(container_id)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/utils/decorators.py", line 21, in wrapped
    return f(self, resource_id, *args, **kwargs)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/api/container.py", line 745, in inspect_container
    self._get(self._url("/containers/{0}/json", container)), True
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/api/client.py", line 220, in _result
    self._raise_for_status(response)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/api/client.py", line 216, in _raise_for_status
    raise create_api_error_from_http_exception(e)
  File "/home/ubuntu/.virtualenvs/refinery-platform/lib/python2.7/site-packages/docker/errors.py", line 30, in create_api_error_from_http_exception
    raise cls(e, response=response, explanation=explanation)
NotFound: 404 Client Error: Not Found ("No such container: asdf")

Expected behavior

No internal server error

Notes

This results in numerous error report emails when these URLs are accessed by indexing bots like the google-bot.

[mccalluc]

Plan is to capture the error in djanago_docker, render a friendlier page (perhaps status 503?) and on that page have either a meta or js refresh so the client will ping until the visualization is available.

This replaces #2074.

[mccalluc]

With #2100, the user will now see the please-wait page... even if they just have a gibberish url. We have no way to tell right now if what they've provided is a container that hasn't quite started, or something they invented. -> Down the road, we'll probably need to keep track of state in a db (particularly if we want to wake up containers that have been paused.)