feat: add --run to llama stack build (#1156)

# What does this PR do?

--run runs the stack that was just build using the same arguments during
the build process (image-name, type, etc)

This simplifies the workflow a lot and makes the UX better for most
local users trying to get started rather than having to match the flags
of the two commands (build and then run)

Also, moved `ImageType` to distribution.utils since there were circular
import errors with its old location

## Test Plan

tested locally using the following command: 

`llama stack build --run --template ollama --image-type venv`

Signed-off-by: Charlie Doern <cdoern@redhat.com>

llama_stack/distribution/build.py

@@ -7,7 +7,6 @@
 import importlib.resources
 import logging
 import sys
-from enum import Enum
 from pathlib import Path
 from typing import Dict, List
 
@@ -18,6 +17,7 @@ from llama_stack.distribution.datatypes import BuildConfig, Provider
 from llama_stack.distribution.distribution import get_provider_registry
 from llama_stack.distribution.utils.config_dirs import BUILDS_BASE_DIR
 from llama_stack.distribution.utils.exec import run_command, run_with_pty
+from llama_stack.distribution.utils.image_types import ImageType
 from llama_stack.providers.datatypes import Api
 
 log = logging.getLogger(__name__)
@@ -33,12 +33,6 @@ SERVER_DEPENDENCIES = [
 ]
 
 
-class ImageType(Enum):
-    container = "container"
-    conda = "conda"
-    venv = "venv"
-
-
 class ApiInput(BaseModel):
     api: Api
     provider: str

llama_stack/distribution/utils/exec.py

@@ -12,8 +12,78 @@ import signal
 import subprocess
 import sys
 
+from termcolor import cprint
+
 log = logging.getLogger(__name__)
 
+import importlib
+import json
+from pathlib import Path
+
+from llama_stack.distribution.utils.image_types import ImageType
+
+
+def formulate_run_args(image_type, image_name, config, template_name) -> list:
+    if image_type == ImageType.container.value or config.container_image:
+        script = importlib.resources.files("llama_stack") / "distribution/start_container.sh"
+        image_name = f"distribution-{template_name}" if template_name else config.container_image
+        run_args = [script, image_name]
+    elif image_type == ImageType.conda.value:
+        current_conda_env = os.environ.get("CONDA_DEFAULT_ENV")
+        image_name = image_name or current_conda_env
+        if not image_name:
+            cprint(
+                "No current conda environment detected, please specify a conda environment name with --image-name",
+                color="red",
+            )
+            return
+
+        def get_conda_prefix(env_name):
+            # Conda "base" environment does not end with "base" in the
+            # prefix, so should be handled separately.
+            if env_name == "base":
+                return os.environ.get("CONDA_PREFIX")
+            # Get conda environments info
+            conda_env_info = json.loads(subprocess.check_output(["conda", "info", "--envs", "--json"]).decode())
+            envs = conda_env_info["envs"]
+            for envpath in envs:
+                if envpath.endswith(env_name):
+                    return envpath
+            return None
+
+        print(f"Using conda environment: {image_name}")
+        conda_prefix = get_conda_prefix(image_name)
+        if not conda_prefix:
+            cprint(
+                f"Conda environment {image_name} does not exist.",
+                color="red",
+            )
+            return
+
+        build_file = Path(conda_prefix) / "llamastack-build.yaml"
+        if not build_file.exists():
+            cprint(
+                f"Build file {build_file} does not exist.\n\nPlease run `llama stack build` or specify the correct conda environment name with --image-name",
+                color="red",
+            )
+            return
+
+        script = importlib.resources.files("llama_stack") / "distribution/start_conda_env.sh"
+        run_args = [
+            script,
+            image_name,
+        ]
+    else:
+        # else must be venv since that is the only valid option left.
+        current_venv = os.environ.get("VIRTUAL_ENV")
+        venv = image_name or current_venv
+        script = importlib.resources.files("llama_stack") / "distribution/start_venv.sh"
+        run_args = [
+            script,
+            venv,
+        ]
+    return run_args
+
 
 def run_with_pty(command):
     if sys.platform.startswith("win"):

llama_stack/distribution/utils/image_types.py

@@ -0,0 +1,13 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from enum import Enum
+
+
+class ImageType(Enum):
+    container = "container"
+    conda = "conda"
+    venv = "venv"