From d1ece12c706334899834f290a4d2aa348512c3ee Mon Sep 17 00:00:00 2001
From: Brian Brazil <brian-brazil@users.noreply.github.com>
Date: Thu, 3 Nov 2016 13:34:15 +0000
Subject: [PATCH] Handle null Regex in the config as the empty regex. (#2150)

---
 config/config.go              | 3 +++
 config/config_test.go         | 6 ++++++
 config/testdata/conf.good.yml | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/config/config.go b/config/config.go
index c83b73109..0aadd6d22 100644
--- a/config/config.go
+++ b/config/config.go
@@ -1017,6 +1017,9 @@ func (c *RelabelConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if err := checkOverflow(c.XXX, "relabel_config"); err != nil {
 		return err
 	}
+	if c.Regex.Regexp == nil {
+		c.Regex = MustNewRegexp("")
+	}
 	if c.Modulus == 0 && c.Action == RelabelHashMod {
 		return fmt.Errorf("relabel configuration for hashmod requires non-zero modulus")
 	}
diff --git a/config/config_test.go b/config/config_test.go
index 17642f76c..3c5cf550b 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -115,6 +115,12 @@ var expectedConf = &Config{
 					Regex:       DefaultRelabelConfig.Regex,
 					Replacement: "static",
 					Action:      RelabelReplace,
+				}, {
+					TargetLabel: "abc",
+					Separator:   ";",
+					Regex:       MustNewRegexp(""),
+					Replacement: "static",
+					Action:      RelabelReplace,
 				},
 			},
 		},
diff --git a/config/testdata/conf.good.yml b/config/testdata/conf.good.yml
index 14a8436f8..36177cc98 100644
--- a/config/testdata/conf.good.yml
+++ b/config/testdata/conf.good.yml
@@ -54,6 +54,9 @@ scrape_configs:
     target_label:  cde
   - replacement:   static
     target_label:  abc
+  - regex:
+    replacement:   static
+    target_label:  abc
 
   bearer_token_file: valid_token_file