breaking change: #233 return error struct to avoid panic at runtime

examples/complex-etcd/main.go

@@ -70,7 +70,10 @@ func main() {
 		Prefix:      false,
 		Key:         "single_key",
 	}
-	provider := etcd.Provider(providerCfg)
+	provider, err := etcd.Provider(providerCfg)
+	if err != nil {
+		log.Fatalf("Failed to instantiate etcd provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -109,7 +112,10 @@ func main() {
 		Prefix:      true,
 		Key:         "parent",
 	}
-	provider = etcd.Provider(providerCfg)
+	provider, err = etcd.Provider(providerCfg)
+	if err != nil {
+		log.Fatalf("Failed to instantiate etcd provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -154,7 +160,10 @@ func main() {
 		Key:         "child",
 	}
 
-	provider = etcd.Provider(providerCfg)
+	provider, err = etcd.Provider(providerCfg)
+	if err != nil {
+		log.Fatalf("Failed to instantiate etcd provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -201,7 +210,10 @@ func main() {
 		Key:         "child",
 	}
 
-	provider = etcd.Provider(providerCfg)
+	provider, err = etcd.Provider(providerCfg)
+	if err != nil {
+		log.Fatalf("Failed to instantiate etcd provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -241,7 +253,10 @@ func main() {
 		Key:         "child",
 	}
 
-	provider = etcd.Provider(providerCfg)
+	provider, err = etcd.Provider(providerCfg)
+	if err != nil {
+		log.Fatalf("Failed to instantiate etcd provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)

examples/read-appconfig/main.go

@@ -13,12 +13,16 @@ import (
 var k = koanf.New(".")
 
 func main() {
-	provider := appconfig.Provider(appconfig.Config{
+	provider, err := appconfig.Provider(appconfig.Config{
 		Application:   os.Getenv("AWS_APPCONFIG_APPLICATION"),
 		ClientID:      os.Getenv("AWS_APPCONFIG_CLIENT_ID"),
 		Configuration: os.Getenv("AWS_APPCONFIG_CONFIG_NAME"),
 		Environment:   os.Getenv("AWS_APPCONFIG_ENVIRONMENT"),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate appconfig provider: %v", err)
+	}
+
 	// Load the provider and parse configuration as JSON.
 	if err := k.Load(provider, json.Parser()); err != nil {
 		log.Fatalf("error loading config: %v", err)

examples/read-consul/main.go

@@ -54,12 +54,15 @@ func main() {
 		log.Printf("Couldn't put key.")
 	}
 
-	provider := consul.Provider(consul.Config{
+	provider, err := consul.Provider(consul.Config{
 		Key:      sKey,
 		Recurse:  false,
 		Detailed: false,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -91,12 +94,15 @@ func main() {
 		log.Fatalf("error loading config: %v", err)
 	}
 
-	provider = consul.Provider(consul.Config{
+	provider, err = consul.Provider(consul.Config{
 		Key:      "parent",
 		Recurse:  true,
 		Detailed: false,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -134,12 +140,15 @@ func main() {
 		log.Fatalf("error loading config: %v", err)
 	}
 
-	provider = consul.Provider(consul.Config{
+	provider, err = consul.Provider(consul.Config{
 		Key:      "child",
 		Recurse:  true,
 		Detailed: false,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)
@@ -181,12 +190,15 @@ func main() {
 	sFlags := uint64(42)
 	sVal = "father"
 
-	provider = consul.Provider(consul.Config{
+	provider, err = consul.Provider(consul.Config{
 		Key:      sKey,
 		Recurse:  false,
 		Detailed: true,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		fmt.Printf("error loading config: %v", err)
@@ -213,12 +225,15 @@ func main() {
 
 	sKey = "parent"
 
-	provider = consul.Provider(consul.Config{
+	provider, err = consul.Provider(consul.Config{
 		Key:      sKey,
 		Recurse:  true,
 		Detailed: true,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	if err := kCheck.Load(provider, nil); err != nil {
 		fmt.Printf("error loading config: %v", err)
@@ -255,12 +270,15 @@ func main() {
 	// Watch test
 
 	sKey = "parent"
-	provider = consul.Provider(consul.Config{
+	provider, err = consul.Provider(consul.Config{
 		Key:      sKey,
 		Recurse:  true,
 		Detailed: false,
 		Cfg:      api.DefaultConfig(),
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate consul provider: %v", err)
+	}
 
 	// Getting the old value
 	kCheck.Load(provider, nil)

examples/read-vault/main.go

@@ -14,7 +14,7 @@ import (
 var k = koanf.New(".")
 
 func main() {
-	provider := vault.Provider(vault.Config{
+	provider, err := vault.Provider(vault.Config{
 		Address: os.Getenv("VAULT_ADDRESS"),
 		Token:   os.Getenv("VAULT_TOKEN"),
 		Path:    "secret/data/my-app",
@@ -25,6 +25,9 @@ func main() {
 		// k.String("data.YOUR_KEY") etc. instead of k.String("YOUR_KEY").
 		ExcludeMeta: true,
 	})
+	if err != nil {
+		log.Fatalf("Failed to instantiate vault provider: %v", err)
+	}
 	// Load mapped config from Vault storage.
 	if err := k.Load(provider, nil); err != nil {
 		log.Fatalf("error loading config: %v", err)

providers/appconfig/appconfig.go

@@ -66,10 +66,10 @@ type AppConfig struct {
 }
 
 // Provider returns an AWS AppConfig provider.
-func Provider(cfg Config) *AppConfig {
+func Provider(cfg Config) (*AppConfig, error) {
 	c, err := config.LoadDefaultConfig(context.TODO())
 	if err != nil {
-		return nil
+		return nil, err
 	}
 
 	if cfg.AWSRegion != "" {
@@ -89,7 +89,7 @@ func Provider(cfg Config) *AppConfig {
 	}
 	client := appconfig.NewFromConfig(c)
 
-	return &AppConfig{client: client, config: cfg}
+	return &AppConfig{client: client, config: cfg}, nil
 }
 
 // ProviderWithClient returns an AWS AppConfig provider

providers/consul/consul.go

@@ -37,13 +37,13 @@ type Consul struct {
 }
 
 // Provider returns an instance of the Consul provider.
-func Provider(cfg Config) *Consul {
+func Provider(cfg Config) (*Consul, error) {
 	c, err := api.NewClient(cfg.Cfg)
 	if err != nil {
-		return nil
+		return nil, err
 	}
 
-	return &Consul{client: c, cfg: cfg}
+	return &Consul{client: c, cfg: cfg}, nil
 }
 
 // ReadBytes is not supported by the Consul provider.

providers/etcd/etcd.go

@@ -35,18 +35,18 @@ type Etcd struct {
 }
 
 // Provider returns a provider that takes etcd config.
-func Provider(cfg Config) *Etcd {
+func Provider(cfg Config) (*Etcd, error) {
 	eCfg := clientv3.Config{
 		Endpoints:   cfg.Endpoints,
 		DialTimeout: cfg.DialTimeout,
 	}
 
 	c, err := clientv3.New(eCfg)
 	if err != nil {
-		return nil
+		return nil, err
 	}
 
-	return &Etcd{client: c, cfg: cfg}
+	return &Etcd{client: c, cfg: cfg}, nil
 }
 
 // ReadBytes is not supported by etcd provider.

providers/parameterstore/parameterstore.go

@@ -48,12 +48,12 @@ type ParameterStore[T Input] struct {
 //   - AWS_ACCESS_KEY_ID
 //   - AWS_SECRET_ACCESS_KEY
 //   - AWS_SESSION_TOKEN
-func Provider[T Input](config Config[T]) *ParameterStore[T] {
+func Provider[T Input](config Config[T]) (*ParameterStore[T], error) {
 	c, err := awsconfig.LoadDefaultConfig(context.TODO())
 	if err != nil {
-		return nil
+		return nil, err
 	}
-	return ProviderWithClient[T](config, ssm.NewFromConfig(c))
+	return ProviderWithClient[T](config, ssm.NewFromConfig(c)), nil
 }
 
 // ProviderWithClient returns a ParameterStore provider

providers/vault/vault.go

@@ -56,21 +56,21 @@ type Vault struct {
 }
 
 // Provider returns a provider that takes a Vault config.
-func Provider(cfg Config) *Vault {
+func Provider(cfg Config) (*Vault, error) {
 	httpClient := &http.Client{Timeout: cfg.Timeout, Transport: cfg.Transport}
 	client, err := api.NewClient(&api.Config{Address: cfg.Address, HttpClient: httpClient})
 	if err != nil {
-		return nil
+		return nil, err
 	}
 	if cfg.AuthMethod != nil {
 		if _, err := client.Auth().Login(context.Background(), cfg.AuthMethod); err != nil {
-			return nil
+			return nil, err
 		}
 	} else {
 		client.SetToken(cfg.Token)
 	}
 
-	return &Vault{client: client, cfg: cfg}
+	return &Vault{client: client, cfg: cfg}, nil
 }
 
 // ReadBytes is not supported by the vault provider.