Provide external file storage options for uploaded files

- Provide options in configuration.py to allow external modules to be loaded to provide alternative methods for file upload/download.
- Upload alternative is implemented as a Django Storage class.
- Download alternative is implemented as a Django app.

Signed-off-by: Nathan Ward <[email protected]>

docs/configuration/optional-settings.md

@@ -322,3 +322,55 @@ The password to use when authenticating to the Redis server (optional).
 Default: False
 
 Use secure sockets layer to encrypt the connections to the Redis server.
+
+## Custom Storage
+
+Custom storage classes can be used to store uploaded files (i.e. image attachments) in places other than the filesystem.
+This is useful, for example, if you have a need to store files in object storage services like S3, or in a database of some kind.
+
+You can optionally define an application which is used to serve the files. If this is not provided, the files are expected to be served externally, and access control is not provided by NetBox.
+
+### FILE_STORAGE
+
+Default: None
+
+The storage class. Populates the `DEFAULT_FILE_STORAGE` setting. See [Writing a custom storage system](https://docs.djangoproject.com/en/2.2/howto/custom-file-storage/) for more information on what this needs to provide.
+
+### FILE_STORAGE_APP
+
+Default: None
+
+A Django app to load, in order to view/download files uploaded with `FILE_STORAGE` above.
+
+### FILE_STORAGE_APP_CONFIG
+
+Default: None
+
+A dictionary of config parameters which are set in the settings.py of the main Django application. For example, AWS credentials for S3 in the format required by `django-storages` can be set as follows:
+
+```
+FILE_STORAGE_APP_CONFIG = {
+    'AWS_ACCESS_KEY_ID': 'foo',
+    'AWS_SECRET_ACCESS_KEY': 'bar',
+    ...
+    etc.
+}
+```
+
+### FILE_STORAGE_APP_PREFIX
+
+Default: media
+
+The URL prefix for the above app. Defaults to `media` - which is what NetBox requires for if using the default filesystem storage mechanism.
+
+### FILE_STORAGE_UPLOAD_TO
+
+Default: None
+
+A function name which is provided to the upload_to parameter of ImageField. See [FileField.upload_to](https://docs.djangoproject.com/en/2.2/ref/models/fields/#django.db.models.FileField.upload_to) for more information.
+
+This is generally not required, however, some existing storage plugins require this to be in a specific format.
+
+This is a string, of the form `module_a.module_b.function`. When required, the module is automatically imported, then the function is called.
+
+NetBox requires the resulting name to be of the format `(.*/)?<type>_<id>_<filename>`, where `type` is `instance.content_type.name` (i.e. rack, device, etc.), and `id` is `instance.object_id`. See `netbox.extras.models.image_upload` for an example of this.

netbox/extras/models.py

@@ -11,8 +11,10 @@
 from django.http import HttpResponse
 from django.template import Template, Context
 from django.urls import reverse
+from django.conf import settings
 import graphviz
 from jinja2 import Environment
+import importlib
 
 from dcim.constants import CONNECTION_STATUS_CONNECTED
 from utilities.utils import deepmerge, foreground_color
@@ -574,7 +576,6 @@ def add_power_connections(self, devices):
 #
 
 def image_upload(instance, filename):
-
     path = 'image-attachments/'
 
     # Rename the file to the provided name, if any. Attempt to preserve the file extension.
@@ -591,6 +592,13 @@ class ImageAttachment(models.Model):
     """
     An uploaded image which is associated with an object.
     """
+    if settings.FILE_STORAGE_UPLOAD_TO:
+        module_name, function_name = settings.FILE_STORAGE_UPLOAD_TO.rsplit('.', 1)
+        module = importlib.import_module(module_name)
+        upload_to = getattr(module, function_name)
+    else:
+        upload_to = image_upload
+
     content_type = models.ForeignKey(
         to=ContentType,
         on_delete=models.CASCADE
@@ -601,7 +609,7 @@ class ImageAttachment(models.Model):
         fk_field='object_id'
     )
     image = models.ImageField(
-        upload_to=image_upload,
+        upload_to=upload_to,
         height_field='image_height',
         width_field='image_width'
     )
@@ -621,7 +629,11 @@ class Meta:
     def __str__(self):
         if self.name:
             return self.name
-        filename = self.image.name.rsplit('/', 1)[-1]
+
+        filename = self.image.name
+        if '/' in filename:
+            filename = filename.rsplit('/', 1)[-1]
+
         return filename.split('_', 2)[2]
 
     def delete(self, *args, **kwargs):

netbox/netbox/configuration.example.py

@@ -159,3 +159,20 @@
 SHORT_TIME_FORMAT = 'H:i:s'
 DATETIME_FORMAT = 'N j, Y g:i a'
 SHORT_DATETIME_FORMAT = 'Y-m-d H:i'
+
+# Optional alternative file upload functionality
+
+# Class to use for uploaded file storage
+# FILE_STORAGE = 'custom_storage.storage.Storage'
+
+# Django application for uploaded file storage retrieval
+# FILE_STORAGE_APP = 'custom_storage'
+
+# Custom config settings required by FILE_STORAGE_APP
+# FILE_STORAGE_APP_CONFIG = {'PARAM': 'value'}
+
+# Prefix under which the above app is accessed
+# FILE_STORAGE_APP_PREFIX = 'files'
+
+# Custom 'upload_to' function passed to ImageField/FileField
+# FILE_STORAGE_UPLOAD_TO = 'custom_storage.upload_to'

netbox/netbox/settings.py

@@ -230,9 +230,6 @@
     os.path.join(BASE_DIR, "project-static"),
 )
 
-# Media
-MEDIA_URL = '/{}media/'.format(BASE_PATH)
-
 # Disable default limit of 1000 fields per request. Needed for bulk deletion of objects. (Added in Django 1.10.)
 DATA_UPLOAD_MAX_NUMBER_FIELDS = None
 
@@ -340,6 +337,27 @@
     '::1',
 )
 
+# Custom file upload handling
+if hasattr(configuration, 'FILE_STORAGE'):
+    DEFAULT_FILE_STORAGE = getattr(configuration, 'FILE_STORAGE')
+
+FILE_STORAGE_APP = getattr(configuration, 'FILE_STORAGE_APP', None)
+if FILE_STORAGE_APP:
+    INSTALLED_APPS.append(FILE_STORAGE_APP)
+    FILE_STORAGE_APP_CONFIG = getattr(configuration, 'FILE_STORAGE_APP_CONFIG', {})
+    if FILE_STORAGE_APP_CONFIG:
+        for attr_name, attr_value in FILE_STORAGE_APP_CONFIG.items():
+            globals()[attr_name] = attr_value
+
+# Default MEDIA_URL to /<BASE_PATH>media/, but allow FILE_STORAGE_APP_PREFIX to override it only if FILE_STORAGE_APP is set
+if FILE_STORAGE_APP:
+    FILE_STORAGE_APP_PREFIX = getattr(configuration, 'FILE_STORAGE_APP_PREFIX', 'media')
+else:
+    FILE_STORAGE_APP_PREFIX = 'media'
+
+MEDIA_URL = '/{}{}/'.format(BASE_PATH, FILE_STORAGE_APP_PREFIX)
+
+FILE_STORAGE_UPLOAD_TO = getattr(configuration, 'FILE_STORAGE_UPLOAD_TO', None)
 
 try:
     HOSTNAME = socket.gethostname()

netbox/netbox/urls.py

@@ -73,6 +73,11 @@
         url(r'^__debug__/', include(debug_toolbar.urls)),
     ]
 
+if settings.FILE_STORAGE_APP:
+    _patterns += [
+        url(r'^{}/'.format(settings.FILE_STORAGE_APP_PREFIX), include('{}.urls'.format(settings.FILE_STORAGE_APP))),
+    ]
+
 # Prepend BASE_PATH
 urlpatterns = [
     url(r'^{}'.format(settings.BASE_PATH), include(_patterns))