prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  versioned caching is broken
  On [this line](https://github.com/ocf/ocfweb/blob/e0ca5b9053abf4908fd6dd3ff344724e61c38b53/ocfweb/environment.py#L15) we use a marathon environment variable to determine the cache version. We need to change this to use a Kubernetes things, a la 
  https://kubernetes.io/docs/tasks/inject-data-application/environment-variable-expose-pod-information/.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `ocfweb/environment.py`
  Content:
  ```
  1 """Introspection into the current environment."""
  2 import os
  3 from functools import lru_cache
  4 
  5 
  6 @lru_cache()
  7 def ocfweb_version():
  8     """Return string representing ocfweb version.
  9 
  10     In dev, returns 'dev'. In prod, returns a version
  11     similar to '2015.12.06.02.25-gitb98c8cb6'.
  12     """
  13     # On Marathon, read it out of environ
  14     try:
  15         docker_image, tag = os.environ['MARATHON_APP_DOCKER_IMAGE'].split(':', 1)
  16         return tag
  17     except KeyError:
  18         pass
  19 
  20     # Otherwise, we must be in dev.
  21     return 'dev'
  22
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/ocfweb/environment.py b/ocfweb/environment.py
  --- a/ocfweb/environment.py
  +++ b/ocfweb/environment.py
  @@ -8,12 +8,11 @@
       """Return string representing ocfweb version.
   
       In dev, returns 'dev'. In prod, returns a version
  -    similar to '2015.12.06.02.25-gitb98c8cb6'.
  +    similar to '2019-08-20-T21-10-57-gite0ca5b9'.
       """
  -    # On Marathon, read it out of environ
  +    # On Kubernetes, read it out of environ
       try:
  -        docker_image, tag = os.environ['MARATHON_APP_DOCKER_IMAGE'].split(':', 1)
  -        return tag
  +        return os.environ['OCFWEB_PROD_VERSION']
       except KeyError:
           pass
  
verification_info: {"golden_diff": "diff --git a/ocfweb/environment.py b/ocfweb/environment.py\n--- a/ocfweb/environment.py\n+++ b/ocfweb/environment.py\n@@ -8,12 +8,11 @@\n     \"\"\"Return string representing ocfweb version.\n \n     In dev, returns 'dev'. In prod, returns a version\n-    similar to '2015.12.06.02.25-gitb98c8cb6'.\n+    similar to '2019-08-20-T21-10-57-gite0ca5b9'.\n     \"\"\"\n-    # On Marathon, read it out of environ\n+    # On Kubernetes, read it out of environ\n     try:\n-        docker_image, tag = os.environ['MARATHON_APP_DOCKER_IMAGE'].split(':', 1)\n-        return tag\n+        return os.environ['OCFWEB_PROD_VERSION']\n     except KeyError:\n         pass\n", "issue": "versioned caching is broken\nOn [this line](https://github.com/ocf/ocfweb/blob/e0ca5b9053abf4908fd6dd3ff344724e61c38b53/ocfweb/environment.py#L15) we use a marathon environment variable to determine the cache version. We need to change this to use a Kubernetes things, a la \r\nhttps://kubernetes.io/docs/tasks/inject-data-application/environment-variable-expose-pod-information/.\n", "before_files": [{"content": "\"\"\"Introspection into the current environment.\"\"\"\nimport os\nfrom functools import lru_cache\n\n\n@lru_cache()\ndef ocfweb_version():\n    \"\"\"Return string representing ocfweb version.\n\n    In dev, returns 'dev'. In prod, returns a version\n    similar to '2015.12.06.02.25-gitb98c8cb6'.\n    \"\"\"\n    # On Marathon, read it out of environ\n    try:\n        docker_image, tag = os.environ['MARATHON_APP_DOCKER_IMAGE'].split(':', 1)\n        return tag\n    except KeyError:\n        pass\n\n    # Otherwise, we must be in dev.\n    return 'dev'\n", "path": "ocfweb/environment.py"}], "after_files": [{"content": "\"\"\"Introspection into the current environment.\"\"\"\nimport os\nfrom functools import lru_cache\n\n\n@lru_cache()\ndef ocfweb_version():\n    \"\"\"Return string representing ocfweb version.\n\n    In dev, returns 'dev'. In prod, returns a version\n    similar to '2019-08-20-T21-10-57-gite0ca5b9'.\n    \"\"\"\n    # On Kubernetes, read it out of environ\n    try:\n        return os.environ['OCFWEB_PROD_VERSION']\n    except KeyError:\n        pass\n\n    # Otherwise, we must be in dev.\n    return 'dev'\n", "path": "ocfweb/environment.py"}]}