From 4b3bab890d3316d1471d4a4390a53572a220855b Mon Sep 17 00:00:00 2001
From: Julien Pivotto <roidelapluie@inuits.eu>
Date: Fri, 20 Dec 2019 15:33:33 +0100
Subject: [PATCH] Fix absent output where two label matchers are identical
 (#6493)

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
---
 promql/functions.go         | 17 ++++++++++++++---
 promql/testdata/legacy.test | 11 ++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/promql/functions.go b/promql/functions.go
index f88fd58d4..ec65bdc88 100644
--- a/promql/functions.go
+++ b/promql/functions.go
@@ -480,15 +480,26 @@ func funcAbsent(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
 	if len(vals[0].(Vector)) > 0 {
 		return enh.out
 	}
-	m := []labels.Label{}
+	m := labels.Labels{}
+	empty := []string{}
 
 	if vs, ok := args[0].(*VectorSelector); ok {
 		for _, ma := range vs.LabelMatchers {
-			if ma.Type == labels.MatchEqual && ma.Name != labels.MetricName {
-				m = append(m, labels.Label{Name: ma.Name, Value: ma.Value})
+			if ma.Name == labels.MetricName {
+				continue
+			}
+			if ma.Type == labels.MatchEqual && !m.Has(ma.Name) {
+				m = labels.NewBuilder(m).Set(ma.Name, ma.Value).Labels()
+			} else {
+				empty = append(empty, ma.Name)
 			}
 		}
 	}
+
+	for _, v := range empty {
+		m = labels.NewBuilder(m).Set(v, "").Labels()
+	}
+
 	return append(enh.out,
 		Sample{
 			Metric: labels.New(m...),
diff --git a/promql/testdata/legacy.test b/promql/testdata/legacy.test
index 5ed442133..43faf431c 100644
--- a/promql/testdata/legacy.test
+++ b/promql/testdata/legacy.test
@@ -264,6 +264,15 @@ eval instant at 50m absent(nonexistent)
 eval instant at 50m absent(nonexistent{job="testjob", instance="testinstance", method=~".x"})
 	{instance="testinstance", job="testjob"} 1
 
+eval instant at 50m absent(nonexistent{job="testjob",job="testjob2",foo="bar"})
+	{foo="bar"} 1
+
+eval instant at 50m absent(nonexistent{job="testjob",job="testjob2",job="three",foo="bar"})
+	{foo="bar"} 1
+
+eval instant at 50m absent(nonexistent{job="testjob",job=~"testjob2",foo="bar"})
+	{foo="bar"} 1
+
 eval instant at 50m absent(http_requests)
 
 eval instant at 50m absent(sum(http_requests))
@@ -365,4 +374,4 @@ load 5m
   testmetric1{src="a",dst="b"} 0
   testmetric2{src="a",dst="b"} 1
 
-eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
\ No newline at end of file
+eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})