(relay proxy) migrate configuration management from viper to knadh/ko…

…anf (#706)

cmd/relayproxy/config/config.go

@@ -2,15 +2,25 @@ package config
 
 import (
 	"fmt"
+	"github.com/knadh/koanf/parsers/json"
+	"github.com/knadh/koanf/parsers/toml"
+	"github.com/knadh/koanf/parsers/yaml"
+	"github.com/knadh/koanf/providers/confmap"
+	"github.com/knadh/koanf/providers/env"
+	"github.com/knadh/koanf/providers/file"
+	"github.com/knadh/koanf/providers/posflag"
+	"github.com/knadh/koanf/v2"
 	"net/http"
+	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
 	"github.com/spf13/pflag"
-	"github.com/spf13/viper"
 	"go.uber.org/zap"
 )
 
+var k = koanf.New(".")
 var DefaultRetriever = struct {
 	Timeout      time.Duration
 	HTTPMethod   string
@@ -38,112 +48,121 @@ var DefaultExporter = struct {
 	MaxEventInMemory: 100000,
 }
 
-// ParseConfig is reading the configuration file
-func ParseConfig(log *zap.Logger, version string) (*Config, error) {
-	viper.Set("version", version)
-
-	errBindFlag := viper.BindPFlags(pflag.CommandLine)
-	if errBindFlag != nil {
+// New is reading the configuration file
+func New(flagSet *pflag.FlagSet, log *zap.Logger, version string) (*Config, error) {
+	k.Delete("")
+
+	// Default values
+	_ = k.Load(confmap.Provider(map[string]interface{}{
+		"listen":          "1031",
+		"host":            "localhost",
+		"fileFormat":      "yaml",
+		"restApiTimeout":  5000,
+		"pollingInterval": 60000,
+	}, "."), nil)
+
+	// mapping command line parameters to koanf
+	if errBindFlag := k.Load(posflag.Provider(flagSet, ".", k), nil); errBindFlag != nil {
 		log.Fatal("impossible to parse flag command line", zap.Error(errBindFlag))
 	}
 
 	// Read config file
-	configFile := viper.GetString("config")
-	if configFile != "" {
-		log.Info("reading config from file", zap.String("fileLocation", configFile))
-		viper.SetConfigFile(configFile)
+	configFileLocation, errFileLocation := locateConfigFile(k.String("config"))
+	if errFileLocation != nil {
+		log.Info("not using any configuration file", zap.Error(errFileLocation))
 	} else {
-		log.Info("reading config from default directories")
-		viper.SetConfigName("goff-proxy")
-		viper.AddConfigPath("./")
-		viper.AddConfigPath("/goff/")
-		viper.AddConfigPath("/etc/opt/goff/")
+		ext := filepath.Ext(configFileLocation)
+		var parser koanf.Parser
+		switch strings.ToLower(ext) {
+		case ".toml":
+			parser = toml.Parser()
+			break
+		case ".json":
+			parser = json.Parser()
+			break
+		default:
+			parser = yaml.Parser()
+		}
+
+		if errBindFile := k.Load(file.Provider(configFileLocation), parser); errBindFile != nil {
+			log.Error("error loading file", zap.Error(errBindFile))
+		}
 	}
 
-	viper.SetEnvKeyReplacer(strings.NewReplacer(`.`, `_`))
-	viper.AutomaticEnv()
-	setViperDefault()
+	// Map environment variables
+	_ = k.Load(env.Provider("", ".", func(s string) string {
+		return strings.ReplaceAll(strings.ToLower(s), "_", ".")
+	}), nil)
+
+	_ = k.Set("version", version)
 
-	err := viper.ReadInConfig()
-	if err != nil {
-		return nil, err
-	}
 	proxyConf := &Config{}
-	err = viper.Unmarshal(proxyConf)
-	if err != nil {
-		return nil, err
+	errUnmarshal := k.Unmarshal("", &proxyConf)
+	if errUnmarshal != nil {
+		return nil, errUnmarshal
 	}
 	return proxyConf, nil
 }
 
-// setViperDefault will set default values for the configuration
-func setViperDefault() {
-	viper.SetDefault("listen", "1031")
-	viper.SetDefault("host", "localhost")
-	viper.SetDefault("fileFormat", "yaml")
-	viper.SetDefault("pollingInterval", 60000)
-	viper.SetDefault("restApiTimeout", 5000)
-}
-
 type Config struct {
 	// ListenPort (optional) is the port we are using to start the proxy
-	ListenPort int `mapstructure:"listen"`
+	ListenPort int `mapstructure:"listen" koanf:"listen"`
 
 	// HideBanner (optional) if true, we don't display the go-feature-flag relay proxy banner
-	HideBanner bool `mapstructure:"hideBanner"`
+	HideBanner bool `mapstructure:"hideBanner" koanf:"hidebanner"`
 
 	// EnableSwagger (optional) to have access to the swagger
-	EnableSwagger bool `mapstructure:"enableSwagger"`
+	EnableSwagger bool `mapstructure:"enableSwagger" koanf:"enableswagger"`
 
 	// Host should be set if you are using swagger (default is localhost)
-	Host string `mapstructure:"host"`
+	Host string `mapstructure:"host" koanf:"host"`
 
 	// Debug (optional) if true, go-feature-flag relay proxy will run on debug mode, with more logs and custom responses
-	Debug bool `mapstructure:"debug"`
+	Debug bool `mapstructure:"debug" koanf:"debug"`
 
 	// PollingInterval (optional) Poll every X time
 	// The minimum possible is 1 second
 	// Default: 60 seconds
-	PollingInterval int `mapstructure:"pollingInterval"`
+	PollingInterval int `koanf:"pollinginterval" mapstructure:"pollingInterval"`
 
 	// FileFormat (optional) is the format of the file to retrieve (available YAML, TOML and JSON)
 	// Default: YAML
-	FileFormat string `mapstructure:"fileFormat"`
+	FileFormat string `mapstructure:"fileFormat" koanf:"fileformat"`
 
 	// StartWithRetrieverError (optional) If true, the relay proxy will start even if we did not get any flags from
 	// the retriever. It will serve only default values until the retriever returns the flags.
 	// The init method will not return any error if the flag file is unreachable.
 	// Default: false
-	StartWithRetrieverError bool `mapstructure:"startWithRetrieverError"`
+	StartWithRetrieverError bool `mapstructure:"startWithRetrieverError" koanf:"startwithretrievererror"`
 
 	// Retriever is the configuration on how to retrieve the file
-	Retriever *RetrieverConf `mapstructure:"retriever"`
+	Retriever *RetrieverConf `mapstructure:"retriever" koanf:"retriever"`
 
 	// Retrievers is the exact same things than Retriever but allows to give more than 1 retriever at the time.
 	// We are dealing with config files in order, if you have the same flag name in multiple files it will be override
 	// based of the order of the retrievers in the slice.
 	//
 	// Note: If both Retriever and Retrievers are set, we will start by calling the Retriever and,
 	// after we will use the order of Retrievers.
-	Retrievers *[]RetrieverConf `mapstructure:"retrievers"`
+	Retrievers *[]RetrieverConf `mapstructure:"retrievers" koanf:"retrievers"`
 
 	// Exporter is the configuration on how to export data
-	Exporter *ExporterConf `mapstructure:"exporter"`
+	Exporter *ExporterConf `mapstructure:"exporter" koanf:"exporter"`
 
 	// Notifiers is the configuration on where to notify a flag change
-	Notifiers []NotifierConf `mapstructure:"notifier"`
+	Notifiers []NotifierConf `mapstructure:"notifier" koanf:"notifier"`
 
 	// RestAPITimeout is the timeout on the API.
-	RestAPITimeout int `mapstructure:"restApiTimeout"`
+	RestAPITimeout int `mapstructure:"restApiTimeout" koanf:"restapitimeout"`
 
 	// Version is the version of the relay-proxy
-	Version string
+	Version string `mapstructure:"version" koanf:"version"`
 
 	// APIKeys list of API keys that authorized to use endpoints
-	APIKeys []string
+	APIKeys []string `mapstructure:"apiKeys" koanf:"apikeys"`
 
 	// StartAsAwsLambda (optional) if true the relay proxy will start ready to be launch as AWS Lambda
-	StartAsAwsLambda bool `mapstructure:"startAsAwsLambda"`
+	StartAsAwsLambda bool `mapstructure:"startAsAwsLambda" koanf:"startasawslambda"`
 
 	// ---- private fields
 
@@ -207,3 +226,35 @@ func (c *Config) IsValid() error {
 
 	return nil
 }
+
+// locateConfigFile is selecting the configuration file we will use.
+func locateConfigFile(inputFilePath string) (string, error) {
+	filename := "goff-proxy"
+	defaultLocations := []string{
+		"./",
+		"/goff/",
+		"/etc/opt/goff/",
+	}
+	supportedExtensions := []string{
+		"yaml",
+		"toml",
+		"json",
+	}
+
+	if inputFilePath != "" {
+		if _, err := os.Stat(inputFilePath); err != nil {
+			return "", fmt.Errorf("impossible to find config file %s", inputFilePath)
+		}
+		return inputFilePath, nil
+	}
+	for _, location := range defaultLocations {
+		for _, ext := range supportedExtensions {
+			configFile := fmt.Sprintf("%s%s.%s", location, filename, ext)
+			if _, err := os.Stat(configFile); err == nil {
+				return configFile, nil
+			}
+		}
+	}
+	return "", fmt.Errorf(
+		"impossible to find config file in the default locations [%s]", strings.Join(defaultLocations, ","))
+}