Add support for deployment ID (#6144)

deployment ID helps in identifying a minio deployment in the case of remote
logging targets.

cmd/format-xl_test.go

@@ -472,6 +472,61 @@ func TestGetFormatXLInQuorumCheck(t *testing.T) {
 	}
 }
 
+// Tests formatXLGetDeploymentID()
+func TestGetXLID(t *testing.T) {
+	setCount := 2
+	disksPerSet := 8
+
+	format := newFormatXLV3(setCount, disksPerSet)
+	formats := make([]*formatXLV3, 16)
+
+	for i := 0; i < setCount; i++ {
+		for j := 0; j < disksPerSet; j++ {
+			newFormat := *format
+			newFormat.XL.This = format.XL.Sets[i][j]
+			formats[i*disksPerSet+j] = &newFormat
+		}
+	}
+
+	// Return a format from list of formats in quorum.
+	quorumFormat, err := getFormatXLInQuorum(formats)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Check if the reference format and input formats are same.
+	var id string
+	if id, err = formatXLGetDeploymentID(quorumFormat, formats); err != nil {
+		t.Fatal(err)
+	}
+
+	if id == "" {
+		t.Fatal("ID cannot be empty.")
+	}
+
+	formats[0] = nil
+	if id, err = formatXLGetDeploymentID(quorumFormat, formats); err != nil {
+		t.Fatal(err)
+	}
+	if id == "" {
+		t.Fatal("ID cannot be empty.")
+	}
+
+	formats[1].XL.Sets[0][0] = "bad-uuid"
+	if id, err = formatXLGetDeploymentID(quorumFormat, formats); err != nil {
+		t.Fatal(err)
+	}
+
+	if id == "" {
+		t.Fatal("ID cannot be empty.")
+	}
+
+	formats[2].ID = "bad-id"
+	if id, err = formatXLGetDeploymentID(quorumFormat, formats); err != errCorruptedFormat {
+		t.Fatal("Unexpected Success")
+	}
+}
+
 // Initialize new format sets.
 func TestNewFormatSets(t *testing.T) {
 	setCount := 2