add text completion format support

docs/my-website/docs/tutorials/text_completion.md

@@ -0,0 +1,38 @@
+# Using Text Completion Format - with Completion()
+
+If your prefer interfacing with the OpenAI Text Completion format this tutorial covers how to use LiteLLM in this format
+```python
+response = openai.Completion.create(
+    model="text-davinci-003",
+    prompt='Write a tagline for a traditional bavarian tavern',
+    temperature=0,
+    max_tokens=100)
+```
+
+## Using LiteLLM in the Text Completion format
+### With gpt-3.5-turbo
+```python
+response = openai.Completion.create(
+    model="gpt-3.5-turbo",
+    prompt='Write a tagline for a traditional bavarian tavern',
+    temperature=0,
+    max_tokens=100)
+```
+
+### With text-davinci-003
+```python
+response = openai.Completion.create(
+    model="text-davinci-003",
+    prompt='Write a tagline for a traditional bavarian tavern',
+    temperature=0,
+    max_tokens=100)
+```
+
+### With llama2
+```python
+response = openai.Completion.create(
+    model="togethercomputer/llama-2-70b-chat",
+    prompt='Write a tagline for a traditional bavarian tavern',
+    temperature=0,
+    max_tokens=100)
+```

litellm/main.py

@@ -64,8 +64,8 @@ async def acompletion(*args, **kwargs):
 )  ## set timeouts, in case calls hang (e.g. Azure) - default is 600s, override with `force_timeout`
 def completion(
     model,
-    messages,  # required params
     # Optional OpenAI params: see https://platform.openai.com/docs/api-reference/chat/create
+    messages=[],
     functions=[],
     function_call="",  # optional params
     temperature=1,
@@ -91,6 +91,7 @@ def completion(
     custom_llm_provider=None,
     custom_api_base=None,
     litellm_call_id=None,
+    prompt="", # allow completion to be used as textCompletion or as ChatCompletion
     # model specific optional params
     # used by text-bison only
     top_k=40,
@@ -101,6 +102,8 @@ def completion(
     try:
         if fallbacks != []:
             return completion_with_fallbacks(**args)
+        if messages == [] and prompt!="":
+            messages = [{"role": "user", "content": prompt}]
         if litellm.model_alias_map and model in litellm.model_alias_map:
             args["model_alias_map"] = litellm.model_alias_map
             model = litellm.model_alias_map[model] # update the model to the actual value if an alias has been passed in

litellm/tests/test_completion.py

@@ -142,6 +142,17 @@ def test_completion_openai():
     except Exception as e:
         pytest.fail(f"Error occurred: {e}")
 
+def test_completion_openai_prompt():
+    try:
+        response = completion(model="gpt-3.5-turbo", prompt="What's the weather in SF?")
+        response_str = response["choices"][0]["message"]["content"]
+        response_str_2 = response.choices[0].message.content
+        print(response)
+        assert response_str == response_str_2
+        assert type(response_str) == str
+        assert len(response_str) > 1
+    except Exception as e:
+        pytest.fail(f"Error occurred: {e}")
 
 def test_completion_text_openai():
     try: