Renamed collector, aggregator to api server, api folder to agent (#133)

* Renamed aggregator -> apiServer.

* Format errors with container names.

* Renamed collector -> apiServer.

* Rephrased help messages.

* Moved api -> agent.

* Continue renameing api -> agent in Makefile and Dockerfiles.

agent/pkg/utils/utils.go

@@ -0,0 +1,61 @@
+package utils
+
+import (
+	"github.com/gofiber/fiber/v2"
+	"github.com/romana/rlog"
+	"log"
+	"net/url"
+	"os"
+	"os/signal"
+	"reflect"
+	"syscall"
+)
+
+// StartServer starts the server with a graceful shutdown
+func StartServer(app *fiber.App) {
+	signals := make(chan os.Signal, 2)
+	signal.Notify(signals,
+		os.Interrupt,  	  // this catch ctrl + c
+		syscall.SIGTSTP,  // this catch ctrl + z
+	)
+
+	go func() {
+		_ = <-signals
+		rlog.Infof("Shutting down...")
+		_ = app.Shutdown()
+	}()
+
+	// Run server.
+	if err := app.Listen(":8899"); err != nil {
+		log.Printf("Oops... Server is not running! Reason: %v", err)
+	}
+}
+
+func ReverseSlice(data interface{}) {
+	value := reflect.ValueOf(data)
+	valueLen := value.Len()
+	for i := 0; i <= int((valueLen-1)/2); i++ {
+		reverseIndex := valueLen - 1 - i
+		tmp := value.Index(reverseIndex).Interface()
+		value.Index(reverseIndex).Set(value.Index(i))
+		value.Index(i).Set(reflect.ValueOf(tmp))
+	}
+}
+
+func CheckErr(e error) {
+	if e != nil {
+		log.Printf("%v", e)
+		//panic(e)
+	}
+}
+
+func SetHostname(address, newHostname string) string {
+	replacedUrl, err := url.Parse(address)
+	if err != nil{
+		log.Printf("error replacing hostname to %s in address %s, returning original %v",newHostname, address, err)
+		return address
+	}
+	replacedUrl.Host = newHostname
+	return replacedUrl.String()
+
+}