fix: Update watsonx.ai provider to use LiteLLM mixin and list all models (#3674)

# What does this PR do?

- The watsonx.ai provider now uses the LiteLLM mixin instead of using
IBM's library, which does not seem to be working (see #3165 for
context).
- The watsonx.ai provider now lists all the models available by calling
the watsonx.ai server instead of having a hard coded list of known
models. (That list gets out of date quickly)
- An edge case in
[llama_stack/core/routers/inference.py](https://github.com/llamastack/llama-stack/pull/3674/files#diff-a34bc966ed9befd9f13d4883c23705dff49be0ad6211c850438cdda6113f3455)
is addressed that was causing my manual tests to fail.
- Fixes `b64_encode_openai_embeddings_response` which was trying to
enumerate over a dictionary and then reference elements of the
dictionary using .field instead of ["field"]. That method is called by
the LiteLLM mixin for embedding models, so it is needed to get the
watsonx.ai embedding models to work.
- A unit test along the lines of the one in #3348 is added. A more
comprehensive plan for automatically testing the end-to-end
functionality for inference providers would be a good idea, but is out
of scope for this PR.
- Updates to the watsonx distribution. Some were in response to the
switch to LiteLLM (e.g., updating the Python packages needed). Others
seem to be things that were already broken that I found along the way
(e.g., a reference to a watsonx specific doc template that doesn't seem
to exist).

Closes #3165

Also it is related to a line-item in #3387 but doesn't really address
that goal (because it uses the LiteLLM mixin, not the OpenAI one). I
tried the OpenAI one and it doesn't work with watsonx.ai, presumably
because the watsonx.ai service is not OpenAI compatible. It works with
LiteLLM because LiteLLM has a provider implementation for watsonx.ai.

## Test Plan

The test script below goes back and forth between the OpenAI and watsonx
providers. The idea is that the OpenAI provider shows how it should work
and then the watsonx provider output shows that it is also working with
watsonx. Note that the result from the MCP test is not as good (the
Llama 3.3 70b model does not choose tools as wisely as gpt-4o), but it
is still working and providing a valid response. For more details on
setup and the MCP server being used for testing, see [the AI Alliance
sample
notebook](https://github.com/The-AI-Alliance/llama-stack-examples/blob/main/notebooks/01-responses/)
that these examples are drawn from.

```python
#!/usr/bin/env python3

import json
from llama_stack_client import LlamaStackClient
from litellm import completion
import http.client


def print_response(response):
    """Print response in a nicely formatted way"""
    print(f"ID: {response.id}")
    print(f"Status: {response.status}")
    print(f"Model: {response.model}")
    print(f"Created at: {response.created_at}")
    print(f"Output items: {len(response.output)}")
    
    for i, output_item in enumerate(response.output):
        if len(response.output) > 1:
            print(f"\n--- Output Item {i+1} ---")
        print(f"Output type: {output_item.type}")
        
        if output_item.type in ("text", "message"):
            print(f"Response content: {output_item.content[0].text}")
        elif output_item.type == "file_search_call":
            print(f"  Tool Call ID: {output_item.id}")
            print(f"  Tool Status: {output_item.status}")
            # 'queries' is a list, so we join it for clean printing
            print(f"  Queries: {', '.join(output_item.queries)}")
            # Display results if they exist, otherwise note they are empty
            print(f"  Results: {output_item.results if output_item.results else 'None'}")
        elif output_item.type == "mcp_list_tools":
            print_mcp_list_tools(output_item)
        elif output_item.type == "mcp_call":
            print_mcp_call(output_item)
        else:
            print(f"Response content: {output_item.content}")


def print_mcp_call(mcp_call):
    """Print MCP call in a nicely formatted way"""
    print(f"\n🛠️  MCP Tool Call: {mcp_call.name}")
    print(f"   Server: {mcp_call.server_label}")
    print(f"   ID: {mcp_call.id}")
    print(f"   Arguments: {mcp_call.arguments}")
    
    if mcp_call.error:
        print("Error: {mcp_call.error}")
    elif mcp_call.output:
        print("Output:")
        # Try to format JSON output nicely
        try:
            parsed_output = json.loads(mcp_call.output)
            print(json.dumps(parsed_output, indent=4))
        except:
            # If not valid JSON, print as-is
            print(f"   {mcp_call.output}")
    else:
        print("   ⏳ No output yet")


def print_mcp_list_tools(mcp_list_tools):
    """Print MCP list tools in a nicely formatted way"""
    print(f"\n🔧 MCP Server: {mcp_list_tools.server_label}")
    print(f"   ID: {mcp_list_tools.id}")
    print(f"   Available Tools: {len(mcp_list_tools.tools)}")
    print("=" * 80)
    
    for i, tool in enumerate(mcp_list_tools.tools, 1):
        print(f"\n{i}. {tool.name}")
        print(f"   Description: {tool.description}")
        
        # Parse and display input schema
        schema = tool.input_schema
        if schema and 'properties' in schema:
            properties = schema['properties']
            required = schema.get('required', [])
            
            print("   Parameters:")
            for param_name, param_info in properties.items():
                param_type = param_info.get('type', 'unknown')
                param_desc = param_info.get('description', 'No description')
                required_marker = " (required)" if param_name in required else " (optional)"
                print(f"     • {param_name} ({param_type}){required_marker}")
                if param_desc:
                    print(f"       {param_desc}")
        
        if i < len(mcp_list_tools.tools):
            print("-" * 40)


def main():
    """Main function to run all the tests"""
    
    # Configuration
    LLAMA_STACK_URL = "http://localhost:8321/"
    LLAMA_STACK_MODEL_IDS = [
        "openai/gpt-3.5-turbo",
        "openai/gpt-4o",
        "llama-openai-compat/Llama-3.3-70B-Instruct",
        "watsonx/meta-llama/llama-3-3-70b-instruct"
    ]
    
    # Using gpt-4o for this demo, but feel free to try one of the others or add more to run.yaml.
    OPENAI_MODEL_ID = LLAMA_STACK_MODEL_IDS[1]
    WATSONX_MODEL_ID = LLAMA_STACK_MODEL_IDS[-1]
    NPS_MCP_URL = "http://localhost:3005/sse/"
    
    print("=== Llama Stack Testing Script ===")
    print(f"Using OpenAI model: {OPENAI_MODEL_ID}")
    print(f"Using WatsonX model: {WATSONX_MODEL_ID}")
    print(f"MCP URL: {NPS_MCP_URL}")
    print()
    
    # Initialize client
    print("Initializing LlamaStackClient...")
    client = LlamaStackClient(base_url="http://localhost:8321")
    
    # Test 1: List models
    print("\n=== Test 1: List Models ===")
    try:
        models = client.models.list()
        print(f"Found {len(models)} models")
    except Exception as e:
        print(f"Error listing models: {e}")
        raise e
    
    # Test 2: Basic chat completion with OpenAI
    print("\n=== Test 2: Basic Chat Completion (OpenAI) ===")
    try:
        chat_completion_response = client.chat.completions.create(
            model=OPENAI_MODEL_ID,
            messages=[{"role": "user", "content": "What is the capital of France?"}]
        )
        
        print("OpenAI Response:")
        for chunk in chat_completion_response.choices[0].message.content:
            print(chunk, end="", flush=True)
        print()
    except Exception as e:
        print(f"Error with OpenAI chat completion: {e}")
        raise e
    
    # Test 3: Basic chat completion with WatsonX
    print("\n=== Test 3: Basic Chat Completion (WatsonX) ===")
    try:
        chat_completion_response_wxai = client.chat.completions.create(
            model=WATSONX_MODEL_ID,
            messages=[{"role": "user", "content": "What is the capital of France?"}],
        )
        
        print("WatsonX Response:")
        for chunk in chat_completion_response_wxai.choices[0].message.content:
            print(chunk, end="", flush=True)
        print()
    except Exception as e:
        print(f"Error with WatsonX chat completion: {e}")
        raise e
    
    # Test 4: Tool calling with OpenAI
    print("\n=== Test 4: Tool Calling (OpenAI) ===")
    tools = [
        {
            "type": "function",
            "function": {
                "name": "get_current_weather",
                "description": "Get the current weather for a specific location",
                "parameters": {
                    "type": "object",
                    "properties": {
                        "location": {
                            "type": "string",
                            "description": "The city and state, e.g., San Francisco, CA",
                        },
                        "unit": {
                            "type": "string",
                            "enum": ["celsius", "fahrenheit"]
                        },
                    },
                    "required": ["location"],
                },
            },
        }
    ]
    
    messages = [
        {"role": "user", "content": "What's the weather like in Boston, MA?"}
    ]
    
    try:
        print("--- Initial API Call ---")
        response = client.chat.completions.create(
            model=OPENAI_MODEL_ID,
            messages=messages,
            tools=tools,
            tool_choice="auto",  # "auto" is the default
        )
        print("OpenAI tool calling response received")
    except Exception as e:
        print(f"Error with OpenAI tool calling: {e}")
        raise e
    
    # Test 5: Tool calling with WatsonX
    print("\n=== Test 5: Tool Calling (WatsonX) ===")
    try:
        wxai_response = client.chat.completions.create(
            model=WATSONX_MODEL_ID,
            messages=messages,
            tools=tools,
            tool_choice="auto",  # "auto" is the default
        )
        print("WatsonX tool calling response received")
    except Exception as e:
        print(f"Error with WatsonX tool calling: {e}")
        raise e
    
    # Test 6: Streaming with WatsonX
    print("\n=== Test 6: Streaming Response (WatsonX) ===")
    try:
        chat_completion_response_wxai_stream = client.chat.completions.create(
            model=WATSONX_MODEL_ID,
            messages=[{"role": "user", "content": "What is the capital of France?"}],
            stream=True
        )
        print("Model response: ", end="")
        for chunk in chat_completion_response_wxai_stream:
            # Each 'chunk' is a ChatCompletionChunk object.
            # We want the content from the 'delta' attribute.
            if hasattr(chunk, 'choices') and chunk.choices is not None:
                content = chunk.choices[0].delta.content
                # The first few chunks might have None content, so we check for it.
                if content is not None:
                    print(content, end="", flush=True)
        print()
    except Exception as e:
        print(f"Error with streaming: {e}")
        raise e
    
    # Test 7: MCP with OpenAI
    print("\n=== Test 7: MCP Integration (OpenAI) ===")
    try:
        mcp_llama_stack_client_response = client.responses.create(
            model=OPENAI_MODEL_ID,
            input="Tell me about some parks in Rhode Island, and let me know if there are any upcoming events at them.",
            tools=[
                {
                    "type": "mcp",
                    "server_url": NPS_MCP_URL,
                    "server_label": "National Parks Service tools",
                    "allowed_tools": ["search_parks", "get_park_events"],
                }
            ]
        )
        print_response(mcp_llama_stack_client_response)
    except Exception as e:
        print(f"Error with MCP (OpenAI): {e}")
        raise e
    
    # Test 8: MCP with WatsonX
    print("\n=== Test 8: MCP Integration (WatsonX) ===")
    try:
        mcp_llama_stack_client_response = client.responses.create(
            model=WATSONX_MODEL_ID,
            input="What is the capital of France?"
        )
        print_response(mcp_llama_stack_client_response)
    except Exception as e:
        print(f"Error with MCP (WatsonX): {e}")
        raise e
    
    # Test 9: MCP with Llama 3.3
    print("\n=== Test 9: MCP Integration (Llama 3.3) ===")
    try:
        mcp_llama_stack_client_response = client.responses.create(
            model=WATSONX_MODEL_ID,
            input="Tell me about some parks in Rhode Island, and let me know if there are any upcoming events at them.",
            tools=[
                {
                    "type": "mcp",
                    "server_url": NPS_MCP_URL,
                    "server_label": "National Parks Service tools",
                    "allowed_tools": ["search_parks", "get_park_events"],
                }
            ]
        )
        print_response(mcp_llama_stack_client_response)
    except Exception as e:
        print(f"Error with MCP (Llama 3.3): {e}")
        raise e
    
    # Test 10: Embeddings
    print("\n=== Test 10: Embeddings ===")
    try:
        conn = http.client.HTTPConnection("localhost:8321")
        payload = json.dumps({
            "model": "watsonx/ibm/granite-embedding-278m-multilingual",
            "input": "Hello, world!",
        })
        headers = {
            'Content-Type': 'application/json',
            'Accept': 'application/json'
        }
        conn.request("POST", "/v1/openai/v1/embeddings", payload, headers)
        res = conn.getresponse()
        data = res.read()
        print(data.decode("utf-8"))
    except Exception as e:
        print(f"Error with Embeddings: {e}")
        raise e

    print("\n=== Testing Complete ===")


if __name__ == "__main__":
    main()
```

---------

Signed-off-by: Bill Murdock <bmurdock@redhat.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

llama_stack/distributions/watsonx/__init__.py

@@ -3,3 +3,5 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
+
+from .watsonx import get_distribution_template  # noqa: F401