Enforce dependencies check at runtime

Currently the binaries version are only checked when called
with flag "version". Now enforce it so that it fails with explicit
error message in case of missing binary or incorrect version installed.

Also update the dataplaneapi dependency version, as it requires
v2.1 since commit 8b553af

haproxy/haproxy_cmd/run.go

@@ -128,17 +128,20 @@ func CheckEnvironment(dataplaneapiBin, haproxyBin string) error {
 		currVer, e := getVersion(path)
 		if e != nil {
 			err = e
+			return
 		}
 		res, e := compareVersion(currVer, minVer)
 		if e != nil {
 			err = e
+			return
 		}
 		if res < 0 {
 			err = fmt.Errorf("%s version must be > %s, but is: %s", path, minVer, currVer)
+			return
 		}
 	}
 	go ensureVersion(haproxyBin, "2.0")
-	go ensureVersion(dataplaneapiBin, "1.2")
+	go ensureVersion(dataplaneapiBin, "2.1")
 
 	wg.Wait()
 	if err != nil {

main.go

@@ -78,12 +78,11 @@ func main() {
 	flag.Parse()
 	if versionFlag != nil && *versionFlag {
 		fmt.Printf("Version: %s ; BuildTime: %s ; GitHash: %s\n", Version, BuildTime, GitHash)
-		status := 0
-		if err := validateRequirements(*dataplaneBin, *haproxyBin); err != nil {
-			fmt.Printf("ERROR: dataplane API / HAProxy dependencies are not satisfied: %s\n", err)
-			status = 4
-		}
-		os.Exit(status)
+		os.Exit(0)
+	}
+	if err := validateRequirements(*dataplaneBin, *haproxyBin); err != nil {
+		fmt.Printf("ERROR: dataplane API / HAProxy dependencies are not satisfied: %s\n", err)
+		os.Exit(4)
 	}
 
 	ll, err := log.ParseLevel(*logLevel)