golang/docs/configuration.md

Configuration and Logging

This application uses a flexible configuration system that supports YAML files and environment variable overrides. It also features a structured logging setup.

Configuration

The configuration is loaded from a YAML file. By default, the application looks for config/config.yaml. You can specify a different configuration file using the -config CLI flag.

./app -config /path/to/my-config.yaml

Configuration Structure

The configuration file supports the following structure:

# Logging configuration
logging:
  # Log Level: debug, info, warn, error
  level: "info"

# Server configuration
server:
  host: "localhost"
  port: 8080

Environment Variables

All configuration values can be overridden using environment variables. The application uses the APP_ prefix for all environment variables. The variable name is constructed by capitalizing the path to the configuration value and replacing dots/nesting with underscores.

YAML Path	Environment Variable	Description
logging.level	APP_LOGGING_LEVEL	Sets the logging level (debug, info, warn, error)
server.host	APP_SERVER_HOST	Sets the server host address
server.port	APP_SERVER_PORT	Sets the server listening port

Example:

To start the application with debug logging and listening on port 9090:

APP_LOGGING_LEVEL=debug APP_SERVER_PORT=9090 ./app

Logging

The application uses structured logging (JSON format) via the standard library's log/slog package.

Log Levels

The supported log levels are:

• debug: Detailed information for debugging purposes.
• info: General operational events (startup, shutdown, etc.).
• warn: Non-critical errors or potential issues.
• error: Critical errors that require attention.

The log level is configured via the logging.level setting in the configuration file or the APP_LOGGING_LEVEL environment variable.

Log Output

Logs are output to stdout in JSON format to facilitate parsing by log management systems.

Example Log Entry:

{"time":"2023-10-27T10:00:00.123Z","level":"INFO","msg":"Starting application..."}