add support for config file and multiple clusters config (#1)

pkg/cfg/config.go

@@ -19,56 +19,147 @@ package cfg
 import (
 	"crypto/tls"
 	"errors"
+	"fmt"
 	"net/http"
 	"os"
 
+	"github.com/alecthomas/repr"
 	"github.com/elastic/elastic-transport-go/v8/elastictransport"
 	"github.com/elastic/go-elasticsearch/v9"
+	"gopkg.in/yaml.v3"
 )
 
 const (
-	Version string = `v0.0.1`
+	Version string = `v0.0.2`
 )
 
+type Cluster struct {
+	Uri, User, Pass string
+	ES              *elasticsearch.TypedClient
+}
+
 type Config struct {
-	Uri, User, Pass    string
-	ES                 *elasticsearch.TypedClient
-	Debug              bool
+	ConfigFile         string // -c
+	CurrentCluster     string // -C
+	Debug              bool   // -d
+	Clusters           map[string]*Cluster
+	DefaultCluster     *Cluster
 	From, To, MaxItems int
 	Index              string
 	Filter             []string
 	Failed, Partials   bool
 }
 
-func Init() (*Config, error) {
-	cfg := Config{
+func NewConfig() *Config {
+	return &Config{Clusters: map[string]*Cluster{}}
+}
+
+func (conf *Config) Init() error {
+	if conf.ConfigFile != "" {
+		if err := conf.LoadConfig(); err != nil {
+			return err
+		}
+	} else {
+		if err := conf.LoadEnv(); err != nil {
+			return err
+		}
+	}
+
+	if conf.CurrentCluster != "" {
+		current, exists := conf.Clusters[conf.CurrentCluster]
+		if !exists {
+			return fmt.Errorf("no cluster with alias %s configured", conf.CurrentCluster)
+		} else {
+			conf.DefaultCluster = current
+		}
+	}
+
+	if conf.Debug {
+		repr.Println(conf)
+	}
+
+	conf.SetupES()
+
+	return nil
+}
+
+func (conf *Config) LoadEnv() error {
+	cluster := Cluster{
 		Uri:  os.Getenv("ES_URI"),
 		User: os.Getenv("ES_USER"),
 		Pass: os.Getenv("ES_PASS"),
 	}
 
 	switch {
-	case cfg.Uri == "":
-		return nil, errors.New("ES_URI unset")
-	case cfg.User == "":
-		return nil, errors.New("ES_USER unset")
-	case cfg.Pass == "":
-		return nil, errors.New("ES_PASS unset")
+	case cluster.Uri == "":
+		return errors.New("ES_URI unset")
+	case cluster.User == "":
+		return errors.New("ES_USER unset")
+	case cluster.Pass == "":
+		return errors.New("ES_PASS unset")
 	}
 
-	es, _ := elasticsearch.NewTyped(
-		elasticsearch.WithAddresses(cfg.Uri),
-		elasticsearch.WithBasicAuth(cfg.User, cfg.Pass),
-		elasticsearch.WithTransportOptions(
-			elastictransport.WithTransport(
-				&http.Transport{
-					TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
-				},
-			),
-		),
-	)
+	conf.Clusters["default"] = &cluster
+	conf.DefaultCluster = &cluster
 
-	cfg.ES = es
-
-	return &cfg, nil
+	return nil
+}
+
+func (conf *Config) LoadConfig() error {
+	if conf.ConfigFile == "" {
+		return nil
+	}
+
+	data, err := os.ReadFile(conf.ConfigFile)
+	if err != nil {
+		return fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	newconf := &Config{}
+
+	err = yaml.Unmarshal(data, newconf)
+	if err != nil {
+		return fmt.Errorf("failed to unmarshal config file: %w", err)
+	}
+
+	if len(newconf.Clusters) > 0 {
+		conf.Clusters = newconf.Clusters
+
+		_, exists := conf.Clusters["default"]
+		if !exists {
+			// no "default", just use the first we stumble upon
+			for _, cluster := range conf.Clusters {
+				conf.DefaultCluster = cluster
+				break
+			}
+		} else {
+			conf.DefaultCluster = newconf.Clusters["default"]
+		}
+	}
+
+	return nil
+}
+
+func (conf *Config) SetupES() error {
+	for _, cluster := range conf.Clusters {
+		es, err := elasticsearch.NewTyped(
+			elasticsearch.WithAddresses(cluster.Uri),
+			elasticsearch.WithBasicAuth(cluster.User, cluster.Pass),
+			elasticsearch.WithTransportOptions(
+				elastictransport.WithTransport(
+					&http.Transport{
+						TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+					},
+				),
+			),
+		)
+
+		if err != nil {
+			return fmt.Errorf("failed to setup elasticsearch connection: %w", err)
+		}
+
+		cluster.ES = es
+	}
+
+	return nil
 }