SprigConfig

Spring Boot-style configuration for Python applications

View the Project on GitHub derikgw/sprig-config

Getting Started

This guide walks you through installing SprigConfig and loading your first configuration.

Installation

Install SprigConfig from PyPI:

pip install sprig-config

Or with Poetry:

poetry add sprig-config

Requirements: Python 3.11 or later (and earlier than Python 4).

Project Setup

Create a config/ directory in your project root:

my-project/
├── config/
│   ├── application.yml
│   ├── application-dev.yml
│   ├── application-test.yml
│   └── application-prod.yml
├── src/
│   └── ...
└── pyproject.toml

Your First Configuration

Base configuration

Create config/application.yml with shared defaults:

# config/application.yml
server:
  host: localhost
  port: 8080

database:
  pool_size: 5
  timeout: 30

logging:
  level: INFO
  format: "%(levelname)s - %(message)s"

Development overlay

Create config/application-dev.yml for development overrides:

# config/application-dev.yml
server:
  port: 9090

logging:
  level: DEBUG

Production overlay

Create config/application-prod.yml for production:

# config/application-prod.yml
server:
  host: 0.0.0.0

database:
  pool_size: 20

logging:
  level: INFO

Loading Configuration

Basic usage

from sprigconfig import load_config

# Load with explicit profile
cfg = load_config(profile="dev", config_dir="config")

# Access values
print(cfg["server"]["port"])      # 9090
print(cfg["server"]["host"])      # localhost
print(cfg["database"]["pool_size"])  # 5

Dotted-key access

SprigConfig supports convenient dotted-key notation:

# These are equivalent
port = cfg["server"]["port"]
port = cfg["server.port"]
port = cfg.get("server.port")

# With default value
port = cfg.get("server.port", 8080)

Check if key exists

if "server.port" in cfg:
    print("Port is configured")

Profile Selection

Profiles are explicit runtime inputs. Pass the selected profile to load_config(), ConfigLoader, or ConfigSingleton.initialize():

profile = os.environ.get("APP_PROFILE", "dev")
cfg = load_config(profile=profile)

SprigConfig does not select a profile from the environment automatically. Your application owns that policy, which keeps profile selection visible and testable.

The active profile is always available in the config:

print(cfg["app.profile"])  # dev, test, or prod

app.profile is injected from the explicit runtime profile. A value from a configuration file is overwritten.

Configuration Directory

Pass the configuration directory explicitly, or set APP_CONFIG_DIR before loading configuration:

Via parameter

from pathlib import Path
cfg = load_config(profile="dev", config_dir=Path("/opt/myapp/config"))

Via environment variable

export APP_CONFIG_DIR=/opt/myapp/config

SprigConfig does not load .env files itself. If your application uses python-dotenv or another environment loader, invoke it before SprigConfig.

Using ConfigLoader (Modern API)

For more control, use the ConfigLoader class directly:

from pathlib import Path
from sprigconfig import ConfigLoader

loader = ConfigLoader(
    config_dir=Path("config"),
    profile="dev"
)
cfg = loader.load()

Using ConfigSingleton (Application Pattern)

For applications that need global access to configuration:

from sprigconfig import ConfigSingleton

# Initialize once at startup
ConfigSingleton.initialize(profile="prod", config_dir="config")

# Access from anywhere in your application
cfg = ConfigSingleton.get()
print(cfg["database.pool_size"])

Note: initialize() can only be called once. Subsequent calls raise an error.

Environment Variable Expansion

Configuration values can reference environment variables:

# config/application.yml
database:
  host: ${DB_HOST}
  port: ${DB_PORT:5432}    # Default to 5432 if not set
  password: ${DB_PASSWORD}

export DB_HOST=db.example.com
export DB_PASSWORD=secret

cfg = load_config(profile="prod", config_dir="config")
print(cfg["database.host"])  # db.example.com
print(cfg["database.port"])  # 5432 (default)

What’s Next?

Now that you have basic configuration working:

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