feat: add CommonServiceConfig and general config handling based on viper

config/config.go

@@ -2,8 +2,14 @@ package config
 
 import (
 	"context"
+	"fmt"
+	"reflect"
+	"strings"
+	"time"
 
 	"github.com/openmfp/golang-commons/context/keys"
+	"github.com/spf13/pflag"
+	"github.com/spf13/viper"
 )
 
 func SetConfigInContext(ctx context.Context, config any) context.Context {
@@ -13,3 +19,119 @@ func SetConfigInContext(ctx context.Context, config any) context.Context {
 func LoadConfigFromContext(ctx context.Context) any {
 	return ctx.Value(keys.ConfigCtxKey)
 }
+
+type CommonServiceConfig struct {
+	DebugLabelValue         string `mapstructure:"debug-label-value"`
+	MaxConcurrentReconciles int    `mapstructure:"max-concurrent-reconciles"`
+	Environment             string `mapstructure:"environment"`
+	Region                  string `mapstructure:"region"`
+	Kubeconfig              string `mapstructure:"kubeconfig"`
+	Image                   struct {
+		Name string `mapstructure:"image-name"`
+		Tag  string `mapstructure:"image-tag"`
+	} `mapstructure:",squash"`
+	Log struct {
+		Level string `mapstructure:"log-level"`
+
+		NoJson bool `mapstructure:"no-json"`
+	} `mapstructure:",squash"`
+	ShutdownTimeout time.Duration `mapstructure:"shutdown-timeout"`
+	Probes          struct {
+		BindAddress string `mapstructure:"probes-bind-address"`
+	} `mapstructure:",squash"`
+	LeaderElection struct {
+		Enabled bool `mapstructure:"leader-election-enabled"`
+	} `mapstructure:",squash"`
+	Sentry struct {
+		Dsn string `mapstructure:"sentry-dsn"`
+	} `mapstructure:",squash"`
+}
+
+func CommonFlags() *pflag.FlagSet {
+	flagSet := pflag.NewFlagSet("common", pflag.ContinueOnError)
+
+	flagSet.String("debug-label-value", "", "Debug label value")
+	flagSet.Int("max-concurrent-reconciles", 1, "Max concurrent reconciles")
+	flagSet.String("environment", "local", "Environment")
+	flagSet.String("region", "local", "Region")
+	flagSet.String("image-name", "", "Image name")
+	flagSet.String("image-tag", "latest", "Image tag")
+	flagSet.String("log-level", "info", "Log level")
+	flagSet.Bool("log-no-json", false, "Log in JSON format")
+	flagSet.Duration("shutdown-timeout", 1, "Shutdown timeout")
+	flagSet.String("probes-bind-address", ":8090", "Probes bind address")
+	flagSet.Bool("leader-election-enabled", false, "Enable leader election")
+	flagSet.String("sentry-dsn", "", "Sentry DSN")
+
+	return flagSet
+}
+
+// generateFlagSet generates a pflag.FlagSet from a struct based on its `mapstructure` tags.
+func generateFlagSet(config any) *pflag.FlagSet {
+	flagSet := pflag.NewFlagSet("generated", pflag.ContinueOnError)
+	traverseStruct(reflect.ValueOf(config), flagSet, "")
+	return flagSet
+}
+
+// traverseStruct recursively traverses a struct and adds flags to the FlagSet.
+func traverseStruct(value reflect.Value, flagSet *pflag.FlagSet, prefix string) {
+	if value.Kind() == reflect.Ptr {
+		value = value.Elem()
+	}
+
+	if value.Kind() != reflect.Struct {
+		return
+	}
+
+	typ := value.Type()
+	for i := 0; i < value.NumField(); i++ {
+		field := typ.Field(i)
+		fieldValue := value.Field(i)
+
+		// Get the `mapstructure` tag
+		tag := field.Tag.Get("mapstructure")
+		if tag == "" || tag == "-" {
+			continue
+		}
+
+		// Handle nested structs
+		if fieldValue.Kind() == reflect.Struct {
+			if tag == ",squash" {
+				traverseStruct(fieldValue, flagSet, "")
+			} else {
+				traverseStruct(fieldValue, flagSet, prefix+tag+".")
+			}
+			continue
+		}
+
+		// Add flags based on the field type
+		switch fieldValue.Kind() {
+		case reflect.String:
+			flagSet.String(prefix+tag, "", fmt.Sprintf("Set the %s", tag))
+		case reflect.Int, reflect.Int64:
+			if fieldValue.Type() == reflect.TypeOf(time.Duration(0)) {
+				flagSet.Duration(prefix+tag, 0, fmt.Sprintf("Set the %s", tag))
+			} else {
+				flagSet.Int(prefix+tag, 0, fmt.Sprintf("Set the %s", tag))
+			}
+		case reflect.Bool:
+			flagSet.Bool(prefix+tag, false, fmt.Sprintf("Set the %s", tag))
+		}
+	}
+}
+
+func NewConfigFor(serviceConfig any) (*viper.Viper, error) {
+	v := viper.NewWithOptions(
+		viper.EnvKeyReplacer(strings.NewReplacer("-", "_")),
+	)
+
+	v.AutomaticEnv()
+
+	err := v.BindPFlags(CommonFlags())
+	if err != nil {
+		return nil, err
+	}
+	err = v.BindPFlags(generateFlagSet(serviceConfig))
+
+	return v, err
+}

config/config_test.go

@@ -1,17 +1,44 @@
-package config
+package config_test
 
 import (
 	"context"
 	"testing"
+	"time"
 
+	"github.com/openmfp/golang-commons/config"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestSetConfigInContext(t *testing.T) {
 	ctx := context.Background()
-	config := "test"
-	ctx = SetConfigInContext(ctx, config)
+	configStr := "test"
+	ctx = config.SetConfigInContext(ctx, configStr)
+
+	retrievedConfig := config.LoadConfigFromContext(ctx)
+	assert.Equal(t, configStr, retrievedConfig)
+}
+
+func TestNewConfigFor(t *testing.T) {
+
+	type test struct {
+		config.CommonServiceConfig
+		CustomFlag       string `mapstructure:"custom-flag"`
+		CustomFlagInt    int    `mapstructure:"custom-flag-int"`
+		CustomFlagBool   bool   `mapstructure:"custom-flag-bool"`
+		CustomFlagStruct struct {
+			CustomFlagDuration time.Duration `mapstructure:"custom-flag-duration"`
+		} `mapstructure:",squash"`
+		CustomFlagStruct2 struct {
+			CustomFlagDuration time.Duration `mapstructure:"custom-flag-duration-2"`
+		} `mapstructure:"le-flag"`
+	}
+
+	testStruct := test{}
+
+	v, err := config.NewConfigFor(&testStruct)
+	assert.NoError(t, err)
+
+	err = v.Unmarshal(&testStruct)
+	assert.NoError(t, err)
 
-	retrievedConfig := LoadConfigFromContext(ctx)
-	assert.Equal(t, config, retrievedConfig)
 }

go.mod

@@ -19,6 +19,8 @@ require (
 	github.com/openfga/openfga v1.7.0
 	github.com/pkg/errors v0.9.1
 	github.com/rs/zerolog v1.34.0
+	github.com/spf13/pflag v1.0.5
+	github.com/spf13/viper v1.19.0
 	github.com/stretchr/testify v1.10.0
 	github.com/vektah/gqlparser/v2 v2.5.23
 	go.opentelemetry.io/otel v1.35.0
@@ -89,8 +91,6 @@ require (
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/spf13/cast v1.6.0 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/spf13/viper v1.19.0 // indirect
 	github.com/stoewer/go-strcase v1.3.0 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect