Implement basic queue, where is it impossible to run two identical job

in parallel

jobs.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"fmt"
+
 	"github.com/docker/docker/api/types/mount"
 
 	"github.com/nemunaire/minifaas/engine/docker"
@@ -42,6 +44,14 @@ func RunJob(jobtype string) (string, error) {
 		}
 	}
 
+	n, err := CountRunningContainers(jobtype)
+	if err != nil {
+		return "", err
+	}
+	if n > 0 {
+		return "", fmt.Errorf("Please wait, there is already a similar job running.")
+	}
+
 	return docker.Run(
 		jobtype,
 		jobs[jobtype].Image,