From 3ab5fe9d7c3b53ff3556f2795e1d5a69cbc19592 Mon Sep 17 00:00:00 2001
From: servak <fservak@gmail.com>
Date: Wed, 30 Jun 2021 20:04:53 +0900
Subject: [PATCH] fixed disappeared target groups in http_sd #9019

Signed-off-by: servak <fservak@gmail.com>
---
 discovery/http/http.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/discovery/http/http.go b/discovery/http/http.go
index df093b6578..deacc77f07 100644
--- a/discovery/http/http.go
+++ b/discovery/http/http.go
@@ -104,6 +104,7 @@ type Discovery struct {
 	url             string
 	client          *http.Client
 	refreshInterval time.Duration
+	tgLastLength    int
 }
 
 // NewDiscovery returns a new HTTP discovery for the given config.
@@ -183,6 +184,15 @@ func (d *Discovery) refresh(ctx context.Context) ([]*targetgroup.Group, error) {
 		tg.Labels[httpSDURLLabel] = model.LabelValue(d.url)
 	}
 
+	// Generate empty updates for sources that disappeared.
+	l := len(targetGroups)
+	if d.tgLastLength > l {
+		for i := l; i < d.tgLastLength; i++ {
+			targetGroups = append(targetGroups, &targetgroup.Group{Source: urlSource(d.url, i)})
+		}
+	}
+	d.tgLastLength = l
+
 	return targetGroups, nil
 }