[Backport 7.63.x] discovery: module: sort container tags before parsi…

…ng them (#33727)

Co-authored-by: Guillaume Pagnoux <[email protected]>

pkg/collector/corechecks/servicediscovery/module/impl_linux.go

@@ -621,6 +621,9 @@ func getServiceNameFromContainerTags(tags []string) (string, string) {
 		{"kube_service", nil},
 	}
 
+	// Sort the tags to make the function deterministic
+	slices.Sort(tags)
+
 	for _, tag := range tags {
 		// Get index of separator between name and value
 		sepIndex := strings.IndexRune(tag, ':')
@@ -630,6 +633,11 @@ func getServiceNameFromContainerTags(tags []string) (string, string) {
 		}
 
 		for i := range tagsPriority {
+			if tagsPriority[i].tagValue != nil {
+				// We have seen this tag before, we don't need another value.
+				continue
+			}
+
 			if tag[:sepIndex] != tagsPriority[i].tagName {
 				// Not a tag we care about; we skip it
 				continue

pkg/collector/corechecks/servicediscovery/module/impl_linux_test.go

@@ -1042,6 +1042,16 @@ func TestTagsPriority(t *testing.T) {
 			"service",
 			"my_service",
 		},
+		{
+			"multiple tags",
+			[]string{
+				"service:foo",
+				"service:bar",
+				"other:tag",
+			},
+			"service",
+			"bar",
+		},
 	}
 
 	for _, c := range cases {