refactor: install external providers from module (#2637)

# What does this PR do?

Today, external providers are installed via the `external_providers_dir`
in the config. This necessitates users to understand the `ProviderSpec`
and set up their directories accordingly. This process splits up the
config for the stack across multiple files, directories, and formats.

Most (if not all) external providers today have a
[get_provider_spec](559cb18fbb/src/ramalama_stack/provider.py (L9))
method that sits unused. Utilizing this method rather than the
providers.d route allows for a much easier installation process for
external providers and limits the amount of extra configuration a
regular user has to do to get their stack off the ground.

To accomplish this and wire it throughout the build process, Introduce
the concept of a `module` for users to specify for an external provider
upon build time. In order to facilitate this, align the build and run
spec to use `Provider` class rather than the stringified provider_type
that build currently uses.

For example, say this is in your build config:

```
- provider_id: ramalama
  provider_type: remote::ramalama
  module: ramalama_stack
```

during build (in the various `build_...` scripts), additionally to
installing any pip dependencies we will also install this module and use
the `get_provider_spec` method to retrieve the ProviderSpec that is
currently specified using `providers.d`.

In production so far, providing instructions for installing external
providers for users has been difficult: they need to install the module
as a pre-req, create the providers.d directory, copy in the provider
spec, and also copy in the necessary build/run yaml files. Accessing an
external provider should be as easy as possible, and pointing to its
installable module aligns more with the rest of our build and dependency
management process.

For now, `external_providers_dir` still exists as an alternate more
declarative method of using external providers.

## Test Plan

added an integration test installing an external provider from module
and more unit test coverage for `get_provider_registry`


( the warning in yellow is expected, the module is installed inside of
the build env, not where we are running the command)
<img width="1119" height="400" alt="Screenshot 2025-07-24 at 11 30
48 AM"
src="https://github.com/user-attachments/assets/1efbaf45-b9e8-451a-bd63-264ed664706d"
/>

<img width="1154" height="618" alt="Screenshot 2025-07-24 at 11 31
14 AM"
src="https://github.com/user-attachments/assets/feb2b3ea-c5dd-418e-9662-9a3bd5dd6bdc"
/>

---------

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

llama_stack/distribution/build_container.sh

@@ -27,52 +27,103 @@ RUN_CONFIG_PATH=/app/run.yaml
 
 BUILD_CONTEXT_DIR=$(pwd)
 
-if [ "$#" -lt 4 ]; then
-  # This only works for templates
-  echo "Usage: $0 <template_or_config> <image_name> <container_base> <pip_dependencies> [<run_config>] [<special_pip_deps>]" >&2
-  exit 1
-fi
 set -euo pipefail
 
-template_or_config="$1"
-shift
-image_name="$1"
-shift
-container_base="$1"
-shift
-pip_dependencies="$1"
-shift
-
-# Handle optional arguments
-run_config=""
-special_pip_deps=""
-
-# Check if there are more arguments
-# The logics is becoming cumbersom, we should refactor it if we can do better
-if [ $# -gt 0 ]; then
-  # Check if the argument ends with .yaml
-  if [[ "$1" == *.yaml ]]; then
-    run_config="$1"
-    shift
-    # If there's another argument after .yaml, it must be special_pip_deps
-    if [ $# -gt 0 ]; then
-      special_pip_deps="$1"
-    fi
-  else
-    # If it's not .yaml, it must be special_pip_deps
-    special_pip_deps="$1"
-  fi
-fi
-
 # Define color codes
 RED='\033[0;31m'
 NC='\033[0m' # No Color
 
+# Usage function
+usage() {
+  echo "Usage: $0 --image-name <image_name> --container-base <container_base> --normal-deps <pip_dependencies> [--run-config <run_config>] [--external-provider-deps <external_provider_deps>] [--optional-deps <special_pip_deps>]"
+  echo "Example: $0 --image-name llama-stack-img --container-base python:3.12-slim --normal-deps 'numpy pandas' --run-config ./run.yaml --external-provider-deps 'foo' --optional-deps 'bar'"
+  exit 1
+}
+
+# Parse arguments
+image_name=""
+container_base=""
+normal_deps=""
+external_provider_deps=""
+optional_deps=""
+run_config=""
+template_or_config=""
+
+while [[ $# -gt 0 ]]; do
+  key="$1"
+  case "$key" in
+    --image-name)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --image-name requires a string value" >&2
+        usage
+      fi
+      image_name="$2"
+      shift 2
+      ;;
+    --container-base)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --container-base requires a string value" >&2
+        usage
+      fi
+      container_base="$2"
+      shift 2
+      ;;
+    --normal-deps)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --normal-deps requires a string value" >&2
+        usage
+      fi
+      normal_deps="$2"
+      shift 2
+      ;;
+    --external-provider-deps)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --external-provider-deps requires a string value" >&2
+        usage
+      fi
+      external_provider_deps="$2"
+      shift 2
+      ;;
+    --optional-deps)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --optional-deps requires a string value" >&2
+        usage
+      fi
+      optional_deps="$2"
+      shift 2
+      ;;
+    --run-config)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --run-config requires a string value" >&2
+        usage
+      fi
+      run_config="$2"
+      shift 2
+      ;;
+    --template-or-config)
+      if [[ -z "$2" || "$2" == --* ]]; then
+        echo "Error: --template-or-config requires a string value" >&2
+        usage
+      fi
+      template_or_config="$2"
+      shift 2
+      ;;
+    *)
+      echo "Unknown option: $1" >&2
+      usage
+      ;;
+  esac
+done
+
+# Check required arguments
+if [[ -z "$image_name" || -z "$container_base" || -z "$normal_deps" ]]; then
+  echo "Error: --image-name, --container-base, and --normal-deps are required." >&2
+  usage
+fi
+
 CONTAINER_BINARY=${CONTAINER_BINARY:-docker}
 CONTAINER_OPTS=${CONTAINER_OPTS:---progress=plain}
-
 TEMP_DIR=$(mktemp -d)
-
 SCRIPT_DIR=$(dirname "$(readlink -f "$0")")
 source "$SCRIPT_DIR/common.sh"
 
@@ -81,18 +132,15 @@ add_to_container() {
   if [ -t 0 ]; then
     printf '%s\n' "$1" >>"$output_file"
   else
-    # If stdin is not a terminal, read from it (heredoc)
     cat >>"$output_file"
   fi
 }
 
-# Check if container command is available
 if ! is_command_available "$CONTAINER_BINARY"; then
   printf "${RED}Error: ${CONTAINER_BINARY} command not found. Is ${CONTAINER_BINARY} installed and in your PATH?${NC}" >&2
   exit 1
 fi
 
-# Update and install UBI9 components if UBI9 base image is used
 if [[ $container_base == *"registry.access.redhat.com/ubi9"* ]]; then
   add_to_container << EOF
 FROM $container_base
@@ -135,16 +183,16 @@ EOF
 
 # Add pip dependencies first since llama-stack is what will change most often
 # so we can reuse layers.
-if [ -n "$pip_dependencies" ]; then
-  read -ra pip_args <<< "$pip_dependencies"
+if [ -n "$normal_deps" ]; then
+  read -ra pip_args <<<  "$normal_deps"
   quoted_deps=$(printf " %q" "${pip_args[@]}")
   add_to_container << EOF
 RUN $MOUNT_CACHE uv pip install $quoted_deps
 EOF
 fi
 
-if [ -n "$special_pip_deps" ]; then
-  IFS='#' read -ra parts <<<"$special_pip_deps"
+if [ -n "$optional_deps" ]; then
+  IFS='#' read -ra parts <<<"$optional_deps"
   for part in "${parts[@]}"; do
     read -ra pip_args <<< "$part"
     quoted_deps=$(printf " %q" "${pip_args[@]}")
@@ -154,7 +202,33 @@ EOF
   done
 fi
 
-# Function to get Python command
+if [ -n "$external_provider_deps" ]; then
+  IFS='#' read -ra parts <<<"$external_provider_deps"
+  for part in "${parts[@]}"; do
+    read -ra pip_args <<< "$part"
+    quoted_deps=$(printf " %q" "${pip_args[@]}")
+    add_to_container <<EOF
+RUN $MOUNT_CACHE uv pip install $quoted_deps
+EOF
+    add_to_container <<EOF
+RUN python3 - <<PYTHON | $MOUNT_CACHE uv pip install -r -
+import importlib
+import sys
+
+try:
+    package_name = '$part'.split('==')[0].split('>=')[0].split('<=')[0].split('!=')[0].split('<')[0].split('>')[0]
+    module = importlib.import_module(f'{package_name}.provider')
+    spec = module.get_provider_spec()
+    if hasattr(spec, 'pip_packages') and spec.pip_packages:
+        if isinstance(spec.pip_packages, (list, tuple)):
+            print('\n'.join(spec.pip_packages))
+except Exception as e:
+    print(f'Error getting provider spec for {package_name}: {e}', file=sys.stderr)
+PYTHON
+EOF
+  done
+fi
+
 get_python_cmd() {
     if is_command_available python; then
         echo "python"