config

Configuration Management

This package provides configuration management for the GraphQL service using Viper. It supports loading configuration from YAML files and environment variables with proper validation.

Features

• YAML Configuration Files: Load configuration from config.yaml files
• Environment Variable Overrides: Override any configuration value using environment variables
• Validation: Comprehensive validation of all configuration values
• Defaults: Sensible defaults for all configuration options
• Type Safety: Strongly typed configuration structs

Configuration Structure

The configuration is organized into three main sections:

Server Configuration

• port: HTTP server port (default: "8080")
• read_timeout: HTTP read timeout (default: "30s")
• write_timeout: HTTP write timeout (default: "30s")
• idle_timeout: HTTP idle timeout (default: "120s")

Database Configuration

• url: Database connection URL (default: postgres://user:password@localhost:5432/graphql_service?sslmode=disable)
• max_open_conns: Maximum number of open connections (default: 25)
• max_idle_conns: Maximum number of idle connections (default: 5)
• conn_max_lifetime: Maximum connection lifetime (default: "5m")
• conn_max_idle_time: Maximum connection idle time (default: "5m")

Logging Configuration

• level: Log level - debug, info, warn, error (default: "info")
• format: Log format - json, text (default: "json")

Usage

Basic Usage

package main

import (
    "log"
    "github.com/captain-corgi/go-graphql-example/internal/infrastructure/config"
)

func main() {
    // Load configuration
    cfg, err := config.Load()
    if err != nil {
        log.Fatalf("Failed to load configuration: %v", err)
    }

    // Use configuration
    fmt.Printf("Server port: %s\n", cfg.Server.Port)
    fmt.Printf("Database URL: %s\n", cfg.Database.URL)
}

Using MustLoad (panics on error)

func main() {
    // Load configuration and panic if it fails
    cfg := config.MustLoad()
    
    // Use configuration
    startServer(cfg)
}

Configuration Files

File Locations

The configuration loader searches for config.yaml in the following locations:

1. ./configs/config.yaml
2. ./config/config.yaml
3. ./config.yaml

Example Configuration File

server:
  port: "8080"
  read_timeout: "30s"
  write_timeout: "30s"
  idle_timeout: "120s"

database:
  url: "postgres://user:password@localhost:5432/graphql_service?sslmode=disable"
  max_open_conns: 25
  max_idle_conns: 5
  conn_max_lifetime: "5m"
  conn_max_idle_time: "5m"

logging:
  level: "info"
  format: "json"

Environment Variables

All configuration values can be overridden using environment variables with the prefix GRAPHQL_SERVICE_. Nested configuration keys use underscores.

Examples

# Override server port
export GRAPHQL_SERVICE_SERVER_PORT="9090"

# Override database URL
export GRAPHQL_SERVICE_DATABASE_URL="postgres://localhost/mydb"

# Override log level
export GRAPHQL_SERVICE_LOGGING_LEVEL="debug"

# Override log format
export GRAPHQL_SERVICE_LOGGING_FORMAT="text"

# Override database connection settings
export GRAPHQL_SERVICE_DATABASE_MAX_OPEN_CONNS="50"
export GRAPHQL_SERVICE_DATABASE_MAX_IDLE_CONNS="10"

Validation

The configuration system includes comprehensive validation:

• Required Fields: Ensures required fields are not empty
• Positive Values: Validates that numeric values are positive where required
• Enum Values: Validates that string values are from allowed sets
• Logical Constraints: Ensures logical relationships (e.g., max_idle_conns ≤ max_open_conns)

Validation Errors

If validation fails, the loader returns detailed error messages:

config validation failed: server config validation failed: server port is required
config validation failed: logging config validation failed: invalid log level: invalid (must be one of: debug, info, warn, error)

Testing

The package includes comprehensive tests covering:

• Configuration validation
• Environment variable overrides
• Default value handling
• Error conditions

Run tests with:

go test ./internal/infrastructure/config/...

Environment-Specific Configuration

You can create environment-specific configuration files:

• config.development.yaml
• config.production.yaml
• config.test.yaml

Load specific configurations by setting the config name:

// This would be done in the loader if needed
viper.SetConfigName("config.development")