initial commit after one day coding agent session

src/mcp_forge/builder/uv_installer.py

@@ -0,0 +1,158 @@
+"""UV-based package installer for custom environments."""
+
+import tempfile
+import shutil
+from typing import List
+from pathlib import Path
+
+
+class UVInstaller:
+    """Manages UV-based package installation in containers."""
+    
+    def __init__(self, cache_path: Path):
+        """
+        Initialize UV installer.
+        
+        Args:
+            cache_path: Path to UV cache directory
+        """
+        self.cache_path = Path(cache_path)
+        self._ensure_cache_dir()
+    
+    def generate_requirements(self, packages: List[str]) -> str:
+        """
+        Generate requirements.txt content.
+        
+        One package per line with version specifiers preserved.
+        
+        Args:
+            packages: List of package specifications
+        
+        Returns:
+            requirements.txt content
+        """
+        if not packages:
+            return ""
+        
+        return '\n'.join(packages)
+    
+    def generate_containerfile(
+        self,
+        base_image: str,
+        packages: List[str],
+        python_version: str = "3.11"
+    ) -> str:
+        """
+        Generate Containerfile for building custom environment.
+        
+        Containerfile structure optimizes layer caching:
+        1. Base image
+        2. Install UV (cached layer)
+        3. Create non-root user
+        4. Copy requirements.txt (cache-friendly)
+        5. Install packages with UV
+        6. Set working directory
+        
+        Args:
+            base_image: Base container image
+            packages: List of package specifications
+            python_version: Python version (for reference)
+        
+        Returns:
+            Containerfile content
+        """
+        has_packages = bool(packages)
+        
+        containerfile = f"""FROM {base_image}
+
+# Install UV for fast package installation
+RUN pip install --no-cache-dir uv
+
+# Create non-root user for security
+RUN useradd -m -u 1000 -s /bin/bash forge && \\
+    mkdir -p /home/forge/.cache/uv && \\
+    chown -R forge:forge /home/forge
+
+# Switch to non-root user
+USER forge
+WORKDIR /home/forge
+
+# Copy requirements for layer caching
+COPY --chown=forge:forge requirements.txt /home/forge/requirements.txt
+
+"""
+        
+        if has_packages:
+            containerfile += """# Install packages with UV
+RUN uv pip install --system -r requirements.txt
+
+"""
+        
+        containerfile += """# Set working directory
+WORKDIR /home/forge/workspace
+
+# Default command
+CMD ["/bin/bash"]
+"""
+        
+        return containerfile
+    
+    def create_build_context(
+        self,
+        base_image: str,
+        packages: List[str],
+        python_version: str = "3.11"
+    ) -> Path:
+        """
+        Create temporary build context directory.
+        
+        Contains:
+        - Containerfile
+        - requirements.txt
+        
+        Args:
+            base_image: Base container image
+            packages: List of package specifications
+            python_version: Python version
+        
+        Returns:
+            Path to build context directory (caller must cleanup)
+        """
+        # Create temporary directory
+        context_dir = Path(tempfile.mkdtemp(prefix="mcp-forge-build-"))
+        
+        try:
+            # Generate Containerfile
+            containerfile_content = self.generate_containerfile(
+                base_image, packages, python_version
+            )
+            containerfile_path = context_dir / "Containerfile"
+            containerfile_path.write_text(containerfile_content)
+            
+            # Generate requirements.txt
+            requirements_content = self.generate_requirements(packages)
+            requirements_path = context_dir / "requirements.txt"
+            requirements_path.write_text(requirements_content)
+            
+            return context_dir
+            
+        except Exception:
+            # Cleanup on error
+            shutil.rmtree(context_dir, ignore_errors=True)
+            raise
+    
+    def get_cache_volume_mount(self) -> dict:
+        """
+        Get volume mount configuration for UV cache.
+        
+        Returns:
+            Volume mount dict for Podman
+        """
+        return {
+            "bind": "/home/forge/.cache/uv",
+            "mode": "rw"
+        }
+    
+    def _ensure_cache_dir(self) -> None:
+        """Ensure UV cache directory exists."""
+        self.cache_path.mkdir(parents=True, exist_ok=True)