Add configuration management with Viper

- Implement pkg/config package with Viper integration - Support environment variables with DLC_ prefix - Add configurable server host, port, and shutdown timeout - Update server to use configuration values - Add config.example.yaml template file - Update AGENTS.md with configuration documentation - Maintain backward compatibility with default values Configuration options: - DLC_SERVER_HOST (default: 0.0.0.0) - DLC_SERVER_PORT (default: 8080) - DLC_SHUTDOWN_TIMEOUT (default: 30s)
2026-04-03 13:53:57 +02:00
parent e52870480d
commit 8103f64db9
6 changed files with 199 additions and 6 deletions
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -38,6 +38,14 @@ This file documents the AI agents, tools, and development workflow for the Dance
 - Server management guide
 - API endpoint documentation

+### Phase 5: Configuration Management (Completed ✅)
+- Viper integration for configuration
+- Environment variable support with DLC_ prefix
+- Customizable server host/port
+- Configurable shutdown timeout
+- Configuration validation and logging
+- Example configuration file
+
 ## 🛠️ Tools & Technologies

 | Component | Technology | Version |
@@ -45,6 +53,7 @@ This file documents the AI agents, tools, and development workflow for the Dance
 | Language | Go | 1.26.1 |
 | Router | Chi | v5.2.5 |
 | Logging | Zerolog | v1.35.0 |
+| Configuration | Viper | v1.21.0 |
 | Testing | Standard Library | - |
 | Dependency Management | Go Modules | - |

@@ -58,6 +67,8 @@ DanceLessonsCoach/
 │   └── server/         # Web server
 │       └── main.go
 ├── pkg/
+│   ├── config/         # Configuration management
+│   │   └── config.go    # Viper-based config
 │   ├── greet/          # Core domain logic
 │   │   ├── api_v1.go    # API handlers
 │   │   ├── greet.go     # Service implementation
@@ -66,6 +77,7 @@ DanceLessonsCoach/
 │       └── server.go
 ├── go.mod              # Dependencies
 ├── go.sum              # Dependency checksums
+├── config.example.yaml # Configuration template
 ├── README.md           # User documentation
 ├── AGENTS.md           # This file
 └── .gitignore          # Ignore patterns
@@ -98,6 +110,64 @@ Server running on :8080
 - 30-second shutdown timeout
 - Proper resource cleanup

+### Configuration Management
+
+The server supports flexible configuration through environment variables with the `DLC_` prefix:
+
+**Available Configuration Options:**
+
+| Option | Environment Variable | Default Value | Description |
+|--------|---------------------|---------------|-------------|
+| Host | `DLC_SERVER_HOST` | `0.0.0.0` | Server bind address |
+| Port | `DLC_SERVER_PORT` | `8080` | Server listening port |
+| Shutdown Timeout | `DLC_SHUTDOWN_TIMEOUT` | `30s` | Graceful shutdown timeout |
+
+**Usage Examples:**
+
+```bash
+# Custom port
+export DLC_SERVER_PORT=9090
+go run cmd/server/main.go &
+
+# Custom host and port
+export DLC_SERVER_HOST="127.0.0.1"
+export DLC_SERVER_PORT=8081
+go run cmd/server/main.go &
+
+# Custom shutdown timeout
+export DLC_SHUTDOWN_TIMEOUT=45s
+go run cmd/server/main.go &
+```
+
+**Configuration File Support:**
+
+A `config.example.yaml` file is provided as a template:
+
+```yaml
+server:
+  host: "0.0.0.0"
+  port: 8080
+
+shutdown:
+  timeout: 30s
+```
+
+**Configuration Loading:**
+- Environment variables take precedence over defaults
+- All configuration is validated on startup
+- Invalid configurations cause server startup failure
+- Configuration values are logged at startup
+
+**Verification:**
+```bash
+# Test with custom configuration
+DLC_SERVER_PORT=9090 DLC_SERVER_HOST="127.0.0.1" go run cmd/server/main.go
+
+# Verify it's running on the custom port
+curl http://127.0.0.1:9090/api/health
+# Expected: {"status":"healthy"}
+```
+
 ### Checking Server Status

 ```bash
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -7,13 +7,19 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
-	"time"

+	"DanceLessonsCoach/pkg/config"
 	"DanceLessonsCoach/pkg/server"
 	"github.com/rs/zerolog/log"
 )

 func main() {
+	// Load configuration
+	cfg, err := config.LoadConfig()
+	if err != nil {
+		log.Fatal().Err(err).Msg("Failed to load configuration")
+	}
+
 	// Create root context with cancellation
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -27,11 +33,11 @@ func main() {
 	serverCtx, serverStop := context.WithCancel(ctx)
 	
 	go func() {
-		fmt.Println("Server running on :8080")
-		log.Info().Msg("Starting HTTP server on :8080")
+		fmt.Printf("Server running on %s\n", cfg.GetServerAddress())
+		log.Info().Str("address", cfg.GetServerAddress()).Msg("Starting HTTP server")
 		
 		srv := &http.Server{
-			Addr:    ":8080",
+			Addr:    cfg.GetServerAddress(),
 			Handler: server.Router(),
 		}
 		
@@ -40,8 +46,8 @@ func main() {
 			<-sigChan
 			log.Info().Msg("Shutdown signal received")
 			
-			// Create shutdown context with timeout
-			shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 30*time.Second)
+			// Create shutdown context with timeout from config
+			shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), cfg.Shutdown.Timeout)
 			defer shutdownCancel()
 			
 			if err := srv.Shutdown(shutdownCtx); err != nil {
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -0,0 +1,23 @@
+# DanceLessonsCoach Configuration Example
+# This file shows the available configuration options
+# You can use this as a template for your own configuration
+
+# Server configuration
+server:
+  # Host address to bind to (default: "0.0.0.0")
+  host: "0.0.0.0"
+  
+  # Port to listen on (default: 8080)
+  port: 8080
+
+# Shutdown configuration
+shutdown:
+  # Timeout duration for graceful shutdown (default: 30s)
+  # Format: number + unit (s, m, h)
+  timeout: 30s
+
+# Environment Variables
+# You can also configure via environment variables with DLC_ prefix:
+# DLC_SERVER_HOST=0.0.0.0
+# DLC_SERVER_PORT=8080
+# DLC_SHUTDOWN_TIMEOUT=30s
--- a/go.mod
+++ b/go.mod
@@ -3,9 +3,21 @@ module DanceLessonsCoach
 go 1.26.1

 require (
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/go-chi/chi/v5 v5.2.5 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/rs/zerolog v1.35.0 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/spf13/viper v1.21.0 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/sys v0.42.0 // indirect
+	golang.org/x/text v0.28.0 // indirect
 )
--- a/go.sum
+++ b/go.sum
@@ -1,11 +1,36 @@
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/go-chi/chi/v5 v5.2.5 h1:Eg4myHZBjyvJmAFjFvWgrqDTXFyOzjj7YIm3L3mu6Ug=
 github.com/go-chi/chi/v5 v5.2.5/go.mod h1:X7Gx4mteadT3eDOMTsXzmI4/rwUpOwBHLpAfupzFJP0=
+github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
+github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/mattn/go-colorable v0.1.14 h1:9A9LHSqF/7dyVVX6g0U9cwm9pG3kP9gSzcuIPHPsaIE=
 github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
+github.com/pelletier/go-toml/v2 v2.2.4/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
 github.com/rs/zerolog v1.35.0 h1:VD0ykx7HMiMJytqINBsKcbLS+BJ4WYjz+05us+LRTdI=
 github.com/rs/zerolog v1.35.0/go.mod h1:EjML9kdfa/RMA7h/6z6pYmq1ykOuA8/mjWaEvGI+jcw=
+github.com/sagikazarmark/locafero v0.11.0 h1:1iurJgmM9G3PA/I+wWYIOw/5SyBtxapeHDcg+AAIFXc=
+github.com/sagikazarmark/locafero v0.11.0/go.mod h1:nVIGvgyzw595SUSUE6tvCp3YYTeHs15MvlmU87WwIik=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 h1:+jumHNA0Wrelhe64i8F6HNlS8pkoyMv5sreGx2Ry5Rw=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8/go.mod h1:3n1Cwaq1E1/1lhQhtRK2ts/ZwZEhjcQeJQ1RuC6Q/8U=
+github.com/spf13/afero v1.15.0 h1:b/YBCLWAJdFWJTN9cLhiXXcD7mzKn9Dm86dNnfyQw1I=
+github.com/spf13/afero v1.15.0/go.mod h1:NC2ByUVxtQs4b3sIUphxK0NioZnmxgyCrfzeuq8lxMg=
+github.com/spf13/cast v1.10.0 h1:h2x0u2shc1QuLHfxi+cTJvs30+ZAHOGRic8uyGTDWxY=
+github.com/spf13/cast v1.10.0/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
+github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
+github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/spf13/viper v1.21.0 h1:x5S+0EU27Lbphp4UKm1C+1oQO+rKx36vfCoaVebLFSU=
+github.com/spf13/viper v1.21.0/go.mod h1:P0lhsswPGWD/1lZJ9ny3fYnVqxiegrlNrEmgLjbTCAY=
+github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=
+github.com/subosito/gotenv v1.6.0/go.mod h1:Dk4QP5c2W3ibzajGcXpNraDfq2IrhjMIvMSWPKKo0FU=
+go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
+go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
 golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
+golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -0,0 +1,57 @@
+package config
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/rs/zerolog/log"
+	"github.com/spf13/viper"
+)
+
+// Config represents the application configuration
+type Config struct {
+	Server struct {
+		Host string `mapstructure:"host"`
+		Port int    `mapstructure:"port"`
+	}
+	Shutdown struct {
+		Timeout time.Duration `mapstructure:"timeout"`
+	}
+}
+
+// LoadConfig loads configuration from environment variables and defaults
+func LoadConfig() (*Config, error) {
+	v := viper.New()
+	
+	// Set default values
+	v.SetDefault("server.host", "0.0.0.0")
+	v.SetDefault("server.port", 8080)
+	v.SetDefault("shutdown.timeout", 30*time.Second)
+	
+	// Bind environment variables
+	v.AutomaticEnv()
+	v.SetEnvPrefix("DLC") // DanceLessonsCoach prefix
+	v.BindEnv("server.host", "DLC_SERVER_HOST")
+	v.BindEnv("server.port", "DLC_SERVER_PORT")
+	v.BindEnv("shutdown.timeout", "DLC_SHUTDOWN_TIMEOUT")
+	
+	// Unmarshal into Config struct
+	var config Config
+	if err := v.Unmarshal(&config); err != nil {
+		log.Error().Err(err).Msg("Failed to unmarshal config")
+		return nil, fmt.Errorf("config unmarshal error: %w", err)
+	}
+	
+	log.Info().
+		Str("host", config.Server.Host).
+		Int("port", config.Server.Port).
+		Dur("shutdown_timeout", config.Shutdown.Timeout).
+		Msg("Configuration loaded")
+	
+	return &config, nil
+}
+
+// GetServerAddress returns the formatted server address (host:port)
+func (c *Config) GetServerAddress() string {
+	return fmt.Sprintf("%s:%d", c.Server.Host, c.Server.Port)
+}