API: log usage metrics2014.07.1

We are about to be making some changes to our API. It would be
helpful to better understand how its being used. This adds a simple
mechanism to help us track usage of the API.

The metrics are logged in the format:
 <timestamp>: <remote ip>: <stat name>: <fields (optional)>
Example output:
 1407170717.06: 127.0.0.1: REQUEST_KEY:
 1407171070.57: 127.0.0.1: INVALID_KEY:
 1407171191.78: 127.0.0.1: INVALID_API_FORM:
 1407171348.14: 127.0.0.1: FILE_UPLOAD: foo_path,False,45d2f5af78194bbfd

Change-Id: I034e6a9a6e502a76d1f0a48346ad92ebe6c6121a

1 files changed, 34 insertions, 0 deletions

diff --git a/license_protected_downloads/uploads.py b/license_protected_downloads/uploads.py
index 419ce3e..3bf6f67 100644
--- a/license_protected_downloads/uploads.py
+++ b/license_protected_downloads/uploads.py
@@ -1,6 +1,9 @@
+import io
+import fcntl
 import os
 import random
 import shutil
+import time
 
 from django.views.decorators.csrf import csrf_exempt
 from django.http import (
@@ -15,6 +18,30 @@ from models import APIKeyStore
 from common import safe_path_join
 
 
+def _client_ip(request):
+    x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')
+    if x_forwarded_for:
+        return x_forwarded_for.split(',')[0]
+    return request.META.get('REMOTE_ADDR')
+
+
+def _log_metric(request, name, fields=None):
+    """Store information on a given API call.
+
+    This allows us to get some understanding of how this API is being used.
+    """
+    with open('/tmp/llp-stats.txt', 'a') as f:
+        try:
+            fcntl.flock(f, fcntl.LOCK_EX)
+            f.seek(0, io.SEEK_END)
+            f.write('%s: %s: %s: ' % (time.time(), _client_ip(request), name))
+            if fields is not None:
+                f.write(','.join(fields))
+            f.write('\n')
+        finally:
+            fcntl.flock(f, fcntl.LOCK_UN)
+
+
 class UploadFileForm(forms.Form):
     file = forms.FileField()
 
@@ -44,14 +71,19 @@ def file_server_post(request, path):
     """
     if not ("key" in request.POST and
             APIKeyStore.objects.filter(key=request.POST["key"])):
+        _log_metric(request, 'INVALID_KEY')
         return HttpResponseServerError("Invalid key")
 
     api_key = APIKeyStore.objects.filter(key=request.POST["key"])
 
     form = UploadFileForm(request.POST, request.FILES)
     if not form.is_valid() or not path:
+        _log_metric(request, 'INVALID_API_FORM')
         return HttpResponseServerError("Invalid call")
 
+    _log_metric(request, 'FILE_UPLOAD',
+                [path, str(api_key[0].public), request.POST['key']])
+
     path = upload_target_path(
         path, request.POST["key"], public=api_key[0].public)
 
@@ -68,6 +100,7 @@ def file_server_post(request, path):
 
 
 def api_request_key(request):
+    _log_metric(request, 'REQUEST_KEY')
     if("key" in request.GET and
        request.GET["key"] == settings.MASTER_API_KEY and
        settings.MASTER_API_KEY):
@@ -93,6 +126,7 @@ def api_request_key(request):
 
 
 def api_delete_key(request):
+    _log_metric(request, 'DELETE_KEY')
     if "key" not in request.GET:
         return HttpResponseServerError("Invalid key")