Config Skills for LlamaFarm

Specialized patterns and best practices for the LlamaFarm configuration module (config/).

Module Overview

The config module provides YAML/TOML/JSON configuration loading with JSONSchema validation:

File	Purpose
datamodel.py	Generated Pydantic v2 models from JSONSchema
schema.yaml	Source JSONSchema with $ref references
compile_schema.py	Dereferences $ref to create schema.deref.yaml
generate_types.py	Generates Python types via datamodel-codegen
validators.py	Custom validators beyond JSONSchema capabilities
helpers/loader.py	Config loading, saving, and format detection
helpers/generator.py	Template-based config generation

Links to Shared Skills

This module follows Python conventions from the shared skills:

Topic	Link	Key Relevance
Patterns	python-skills/patterns.md	Pydantic v2, dataclasses
Typing	python-skills/typing.md	Type hints, constrained types
Testing	python-skills/testing.md	Pytest fixtures, temp files
Errors	python-skills/error-handling.md	Custom exceptions
Security	python-skills/security.md	Path traversal prevention

Framework-Specific Checklists

Checklist	Description
pydantic.md	Pydantic v2 configuration patterns, nested models, constraints
jsonschema.md	JSONSchema generation, dereferencing, validation

Tech Stack

• Python: 3.11+
• Pydantic: v2 with ConfigDict, Field, constrained types
• JSONSchema: Draft-07 with $ref dereferencing via jsonref
• YAML: ruamel.yaml for comment-preserving read/write
• Code Generation: datamodel-codegen for schema-to-Pydantic

Key Patterns

Generated Pydantic Models

The datamodel.py file is auto-generated from JSONSchema:

# Generated by datamodel-codegen from schema.deref.yaml
from pydantic import BaseModel, ConfigDict, Field, conint, constr

class Database(BaseModel):
    model_config = ConfigDict(extra="forbid")
    name: constr(pattern=r"^[a-z][a-z0-9_]*$", min_length=1, max_length=50)
    type: Type
    config: dict[str, Any] | None = Field(None, description="Database-specific configuration")

Custom Validators for Cross-Field Constraints

JSONSchema draft-07 cannot express all constraints. Custom validators extend validation:

def validate_llamafarm_config(config_dict: dict[str, Any]) -> None:
    """Validate constraints beyond JSONSchema (uniqueness, references)."""
    # Check for duplicate prompt names
    prompt_names = [p.get("name") for p in config_dict.get("prompts", [])]
    duplicates = [name for name in prompt_names if prompt_names.count(name) > 1]
    if duplicates:
        raise ValueError(f"Duplicate prompt set names: {', '.join(set(duplicates))}")

Comment-Preserving YAML with ruamel.yaml

Configuration files preserve user comments when modified:

from ruamel.yaml import YAML
from ruamel.yaml.comments import CommentedMap

def _get_ruamel_yaml() -> YAML:
    yaml_instance = YAML()
    yaml_instance.preserve_quotes = True
    yaml_instance.indent(mapping=2, sequence=4, offset=2)
    return yaml_instance

Directory Structure

config/
├── pyproject.toml       # UV-managed dependencies
├── schema.yaml          # Source JSONSchema with $ref
├── schema.deref.yaml    # Dereferenced schema (generated)
├── datamodel.py         # Pydantic models (generated)
├── compile_schema.py    # Schema compilation script
├── generate_types.py    # Type generation script
├── validators.py        # Custom validation beyond JSONSchema
├── validate_config.py   # CLI validation wrapper
├── __init__.py          # Public API exports
├── helpers/
│   ├── loader.py        # Config loading/saving
│   └── generator.py     # Template-based generation
├── templates/
│   └── default.yaml     # Default config template
└── tests/
    ├── conftest.py      # Shared fixtures
    └── test_*.py        # Test modules

Workflow: Schema Changes

When modifying the configuration schema:

1. Edit schema.yaml (or referenced schemas like ../rag/schema.yaml)
2. Run nx run generate-types to compile and generate types
3. Update validators.py if new cross-field constraints are needed
4. Test with uv run pytest config/tests/

Common Commands

# Generate types from schema
nx run generate-types

# Validate a config file
uv run python config/validate_config.py path/to/llamafarm.yaml --verbose

# Run tests
uv run pytest config/tests/ -v

# Lint and format
ruff check config/ --fix
ruff format config/