Litellm dev 01 27 2025 p3 (#8047)

* docs(reliability.md): add doc on disabling fallbacks per request

* feat(litellm_pre_call_utils.py): support reading request timeout from request headers - new `x-litellm-timeout` param

Allows setting dynamic model timeouts from vercel's AI sdk

* test(test_proxy_server.py): add simple unit test for reading request timeout

* test(test_fallbacks.py): add e2e test to confirm timeout passed in request headers is correctly read

* feat(main.py): support passing metadata to openai in preview

Resolves https://github.com/BerriAI/litellm/issues/6022#issuecomment-2616119371

* fix(main.py): fix passing openai metadata

* docs(request_headers.md): document new request headers

* build: Merge branch 'main' into litellm_dev_01_27_2025_p3

* test: loosen test

docs/my-website/docs/proxy/reliability.md

@@ -1007,7 +1007,34 @@ curl -L -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
 }'
 ```
 
-### Disable Fallbacks per key
+### Disable Fallbacks (Per Request/Key)
+
+
+<Tabs>
+
+<TabItem value="request" label="Per Request">
+
+You can disable fallbacks per key by setting `disable_fallbacks: true` in your request body.
+
+```bash
+curl -L -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
+-H 'Content-Type: application/json' \
+-H 'Authorization: Bearer sk-1234' \
+-d '{
+    "messages": [
+        {
+            "role": "user",
+            "content": "List 5 important events in the XIX century"
+        }
+    ],
+    "model": "gpt-3.5-turbo",
+    "disable_fallbacks": true # 👈 DISABLE FALLBACKS
+}'
+```
+
+</TabItem>
+
+<TabItem value="key" label="Per Key">
 
 You can disable fallbacks per key by setting `disable_fallbacks: true` in your key metadata.
 
@@ -1020,4 +1047,7 @@ curl -L -X POST 'http://0.0.0.0:4000/key/generate' \
         "disable_fallbacks": true
     }
 }'
-```
+```
+
+</TabItem>
+</Tabs>

docs/my-website/docs/proxy/request_headers.md

@@ -0,0 +1,12 @@
+# Request Headers
+
+Special headers that are supported by LiteLLM.
+
+## LiteLLM Headers
+
+`x-litellm-timeout` Optional[float]: The timeout for the request in seconds.
+
+## Anthropic Headers
+
+`anthropic-version` Optional[str]: The version of the Anthropic API to use.  
+`anthropic-beta` Optional[str]: The beta version of the Anthropic API to use.

docs/my-website/sidebars.js

@@ -66,6 +66,7 @@ const sidebars = {
             "proxy/user_keys",
             "proxy/clientside_auth",
             "proxy/response_headers",
+            "proxy/request_headers",
           ],
         },
         {