feat: load config file from url (#1207)

Signed-off-by: DiniFarb <andreas.vogt89@bluewin.ch>

config/config.go

@@ -15,6 +15,9 @@ package config
 
 import (
 	"fmt"
+	"io"
+	"net/http"
+	"net/url"
 	"os"
 
 	"github.com/alecthomas/kingpin/v2"
@@ -35,17 +38,35 @@ type Resolver struct {
 // NewResolver returns a Resolver structure.
 func NewResolver(file string, logger log.Logger) (*Resolver, error) {
 	flags := map[string]string{}
-	_ = level.Info(logger).Log("msg", fmt.Sprintf("Loading configuration file: %v", file))
-	if _, err := os.Stat(file); err != nil {
-		return nil, err
-	}
-	b, err := os.ReadFile(file)
+	var fileBytes []byte
+	url, err := url.ParseRequestURI(file)
 	if err != nil {
 		return nil, err
 	}
+	if url.Scheme == "http" || url.Scheme == "https" {
+		_ = level.Info(logger).Log("msg", fmt.Sprintf("Loading configuration file from URL: %v", file))
+		resp, err := http.Get(file)
+		if err != nil {
+			return nil, err
+		}
+		defer resp.Body.Close()
+		fileBytes, err = io.ReadAll(resp.Body)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		_ = level.Info(logger).Log("msg", fmt.Sprintf("Loading configuration file: %v", file))
+		if _, err := os.Stat(file); err != nil {
+			return nil, err
+		}
+		fileBytes, err = os.ReadFile(file)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	var rawValues map[string]interface{}
-	err = yaml.Unmarshal(b, &rawValues)
+	err = yaml.Unmarshal(fileBytes, &rawValues)
 	if err != nil {
 		return nil, err
 	}