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platform-config

Package: cloud_dog_config
Standard: PS-80 (Configuration Management)
Version: 0.2.0
Status: Implemented

Purpose

Drop-in Python library implementing the PS-80 configuration management standard. Provides deterministic config loading, Vault secret resolution, safe expression evaluation, and an immutable GlobalConfig runtime object.

Key Features

• Canonical precedence chain: os.environ → env-file(s) → config.yaml → defaults.yaml
• Config compile phase: ${vault.*} lookups, ${ENV_VAR} references, || fallbacks, ?: ternaries, + string concatenation, ==/!= equality, ! negation
• Escaped-placeholder compatibility for env/shell/docker: $${...} and \${...} are treated as ${...}
• Vault object/bundle assignment (deep-merge entire secret groups)
• Immutable GlobalConfig snapshot with version tracking
• Safe expression evaluator (no arbitrary code execution)
• Secret redaction utilities
• Hot reload pipeline with audit events
• Post-compile transform hook chain (transforms=[...])
• Environment metadata accessor (get_env_metadata())
• Legacy migration adapter (LegacyConfigAdapter)
• Multi-profile resolver (resolve_profile)
• Typed model binding (bind_model)
• Structured config diff + redacted export utilities
• Reload timeout protection (reload_config(timeout_s=...))
• Pytest plugin with --env enforcement
• Zero framework dependency (works with FastAPI, Flask, CLI, etc.)

Dependencies

• Required: pyyaml
• Optional: hvac (Vault client), pydantic (schema validation)

Expression Language

Config values support ${...} expressions with operators for URL composition and conditional logic:

# URL from parts with fallback defaults
api_url: ${SCHEME || 'https'}://${API_HOST}:${API_PORT || '8080'}/api/v1

# Conditional SSL
verify_ssl: ${ENV == 'production' ? true : false}

# Vault secret with env override
db_password: ${MY_DB_PASS || vault.dev.db.password || 'changeme'}

# String concatenation inside ternary
url: ${SSL ? 'https://' + HOST : 'http://' + HOST}

See Expression Language Reference for full documentation.

Documents

• EXPRESSION-LANGUAGE.md — Expression syntax, operators, URL patterns
• REQUIREMENTS.md — Functional and non-functional requirements
• ARCHITECTURE.md — Module layout, component design, integration pattern
• TESTS.md — Test plan, directory structure, coverage map

Quick Start

from cloud_dog_config import load_config, get_config

config = load_config(env_files=["private/env-test"])
model = get_config("llm.model")

Installation

pip install cloud-dog-config

API Overview

• load_config(...) loads and compiles layered configuration input.
• get_config(...) reads values from the active config snapshot.
• bind_model(...) validates config into typed consumer models.

Examples

• Load layered config from tests/env-UT, config.yaml, and defaults.yaml.
• Resolve Vault-backed values through ${vault.*} expressions at runtime.
• Bind compiled config into a typed model for service startup.

Validation Status (2026-02-18)

• Package implemented and built: cloud_dog_config-0.2.0
• Quality gates run in this uplift:
  • pytest tests --env tests/env-IT -q -> 103 passed, 3 skipped
  • pytest tests --env tests/env-UT -q -> 103 passed, 3 skipped
  • ruff check cloud_dog_config tests -> pass
  • ruff format --check cloud_dog_config tests -> pass
  • python -m build --no-isolation -> pass (sdist + wheel)

Licence

Apache-2.0 — Copyright (c) 2026 Cloud-Dog, Viewdeck Engineering Limited