feat(server): Use system packages for execution (#1252)

# What does this PR do?

Users prefer to rely on the main CLI rather than invoking the server
through a Python module. Users interact with a high-level CLI rather
than needing to know internal module structures.

Now, when running llama stack run <path-to-config>, the server will
attempt to use the system package or a virtual environment if one is
active.

This also eliminates the current process dependency chain when running
from a virtual environment:

-> llama stack run
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -> start_env.sh

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
-> python -m server...

Signed-off-by: Sébastien Han <seb@redhat.com>

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan

Run:

```
ollama run llama3.2:3b-instruct-fp16 --keepalive=2m &
llama stack run ./llama_stack/templates/ollama/run.yaml --disable-ipv6
```

Notice that the server starts and shutdowns normally.

[//]: # (## Documentation)

---------

Signed-off-by: Sébastien Han <seb@redhat.com>
Co-authored-by: Ashwin Bharambe <ashwin.bharambe@gmail.com>

llama_stack/cli/stack/run.py

@@ -56,7 +56,6 @@ class StackRun(Subcommand):
             "--env",
             action="append",
             help="Environment variables to pass to the server in KEY=VALUE format. Can be specified multiple times.",
-            default=[],
             metavar="KEY=VALUE",
         )
         self.parser.add_argument(
@@ -74,7 +73,6 @@ class StackRun(Subcommand):
             type=str,
             help="Image Type used during the build. This can be either conda or container or venv.",
             choices=["conda", "container", "venv"],
-            default="conda",
         )
 
     def _run_stack_run_cmd(self, args: argparse.Namespace) -> None:
@@ -120,20 +118,42 @@ class StackRun(Subcommand):
         except AttributeError as e:
             self.parser.error(f"failed to parse config file '{config_file}':\n {e}")
 
-        run_args = formulate_run_args(args.image_type, args.image_name, config, template_name)
+        # If neither image type nor image name is provided, assume the server should be run directly
+        # using the current environment packages.
+        if not args.image_type and not args.image_name:
+            logger.info("No image type or image name provided. Assuming environment packages.")
+            from llama_stack.distribution.server.server import main as server_main
 
-        run_args.extend([str(config_file), str(args.port)])
+            # Build the server args from the current args passed to the CLI
-        if args.disable_ipv6:
+            server_args = argparse.Namespace()
-            run_args.append("--disable-ipv6")
+            for arg in vars(args):
+                # If this is a function, avoid passing it
+                # "args" contains:
+                # func=<bound method StackRun._run_stack_run_cmd of <llama_stack.cli.stack.run.StackRun object at 0x10484b010>>
+                if callable(getattr(args, arg)):
+                    continue
+                setattr(server_args, arg, getattr(args, arg))
 
-        for env_var in args.env:
+            # Run the server
-            if "=" not in env_var:
+            server_main(server_args)
-                self.parser.error(f"Environment variable '{env_var}' must be in KEY=VALUE format")
+        else:
-            key, value = env_var.split("=", 1)  # split on first = only
+            run_args = formulate_run_args(args.image_type, args.image_name, config, template_name)
-            if not key:
-                self.parser.error(f"Environment variable '{env_var}' has empty key")
-            run_args.extend(["--env", f"{key}={value}"])
 
-        if args.tls_keyfile and args.tls_certfile:
+            run_args.extend([str(config_file), str(args.port)])
-            run_args.extend(["--tls-keyfile", args.tls_keyfile, "--tls-certfile", args.tls_certfile])
+            if args.disable_ipv6:
-        run_with_pty(run_args)
+                run_args.append("--disable-ipv6")
+
+            if args.env:
+                for env_var in args.env:
+                    if "=" not in env_var:
+                        self.parser.error(f"Environment variable '{env_var}' must be in KEY=VALUE format")
+                        return
+                    key, value = env_var.split("=", 1)  # split on first = only
+                    if not key:
+                        self.parser.error(f"Environment variable '{env_var}' has empty key")
+                        return
+                    run_args.extend(["--env", f"{key}={value}"])
+
+            if args.tls_keyfile and args.tls_certfile:
+                run_args.extend(["--tls-keyfile", args.tls_keyfile, "--tls-certfile", args.tls_certfile])
+            run_with_pty(run_args)

llama_stack/distribution/server/server.py

@@ -17,7 +17,7 @@ import warnings
 from contextlib import asynccontextmanager
 from importlib.metadata import version as parse_version
 from pathlib import Path
-from typing import Any, List, Union
+from typing import Any, List, Optional, Union
 
 import yaml
 from fastapi import Body, FastAPI, HTTPException, Request
@@ -314,11 +314,17 @@ class ClientVersionMiddleware:
         return await self.app(scope, receive, send)
 
 
-def main():
+def main(args: Optional[argparse.Namespace] = None):
     """Start the LlamaStack server."""
     parser = argparse.ArgumentParser(description="Start the LlamaStack server.")
     parser.add_argument(
         "--yaml-config",
+        dest="config",
+        help="(Deprecated) Path to YAML configuration file - use --config instead",
+    )
+    parser.add_argument(
+        "--config",
+        dest="config",
         help="Path to YAML configuration file",
     )
     parser.add_argument(
@@ -348,7 +354,19 @@ def main():
         required="--tls-keyfile" in sys.argv,
     )
 
-    args = parser.parse_args()
+    # Determine whether the server args are being passed by the "run" command, if this is the case
+    # the args will be passed as a Namespace object to the main function, otherwise they will be
+    # parsed from the command line
+    if args is None:
+        args = parser.parse_args()
+
+    # Check for deprecated argument usage
+    if "--yaml-config" in sys.argv:
+        warnings.warn(
+            "The '--yaml-config' argument is deprecated and will be removed in a future version. Use '--config' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
 
     if args.env:
         for env_pair in args.env:
@@ -360,9 +378,9 @@ def main():
                 logger.error(f"Error: {str(e)}")
                 sys.exit(1)
 
-    if args.yaml_config:
+    if args.config:
         # if the user provided a config file, use it, even if template was specified
-        config_file = Path(args.yaml_config)
+        config_file = Path(args.config)
         if not config_file.exists():
             raise ValueError(f"Config file {config_file} does not exist")
         logger.info(f"Using config file: {config_file}")