config: forbid nil regexp matchers (#2083)

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

config/config.go

@@ -579,7 +579,7 @@ type Route struct {
 	GroupByAll bool              `yaml:"-" json:"-"`
 
 	Match    map[string]string `yaml:"match,omitempty" json:"match,omitempty"`
-	MatchRE  map[string]Regexp `yaml:"match_re,omitempty" json:"match_re,omitempty"`
+	MatchRE  MatchRegexps      `yaml:"match_re,omitempty" json:"match_re,omitempty"`
 	Continue bool              `yaml:"continue,omitempty" json:"continue,omitempty"`
 	Routes   []*Route          `yaml:"routes,omitempty" json:"routes,omitempty"`
 
@@ -601,11 +601,6 @@ func (r *Route) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		}
 	}
 
-	for k := range r.MatchRE {
-		if !model.LabelNameRE.MatchString(k) {
-			return fmt.Errorf("invalid label name %q", k)
-		}
-	}
 	for _, l := range r.GroupByStr {
 		if l == "..." {
 			r.GroupByAll = true
@@ -650,13 +645,13 @@ type InhibitRule struct {
 	SourceMatch map[string]string `yaml:"source_match,omitempty" json:"source_match,omitempty"`
 	// SourceMatchRE defines pairs like SourceMatch but does regular expression
 	// matching.
-	SourceMatchRE map[string]Regexp `yaml:"source_match_re,omitempty" json:"source_match_re,omitempty"`
+	SourceMatchRE MatchRegexps `yaml:"source_match_re,omitempty" json:"source_match_re,omitempty"`
 	// TargetMatch defines a set of labels that have to equal the given
 	// value for target alerts.
 	TargetMatch map[string]string `yaml:"target_match,omitempty" json:"target_match,omitempty"`
 	// TargetMatchRE defines pairs like TargetMatch but does regular expression
 	// matching.
-	TargetMatchRE map[string]Regexp `yaml:"target_match_re,omitempty" json:"target_match_re,omitempty"`
+	TargetMatchRE MatchRegexps `yaml:"target_match_re,omitempty" json:"target_match_re,omitempty"`
 	// A set of labels that must be equal between the source and target alert
 	// for them to be a match.
 	Equal model.LabelNames `yaml:"equal,omitempty" json:"equal,omitempty"`
@@ -675,24 +670,12 @@ func (r *InhibitRule) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		}
 	}
 
-	for k := range r.SourceMatchRE {
-		if !model.LabelNameRE.MatchString(k) {
-			return fmt.Errorf("invalid label name %q", k)
-		}
-	}
-
 	for k := range r.TargetMatch {
 		if !model.LabelNameRE.MatchString(k) {
 			return fmt.Errorf("invalid label name %q", k)
 		}
 	}
 
-	for k := range r.TargetMatchRE {
-		if !model.LabelNameRE.MatchString(k) {
-			return fmt.Errorf("invalid label name %q", k)
-		}
-	}
-
 	return nil
 }
 
@@ -724,6 +707,26 @@ func (c *Receiver) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return nil
 }
 
+// MatchRegexps represents a map of Regexp.
+type MatchRegexps map[string]Regexp
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface for MatchRegexps.
+func (m *MatchRegexps) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type plain MatchRegexps
+	if err := unmarshal((*plain)(m)); err != nil {
+		return err
+	}
+	for k, v := range *m {
+		if !model.LabelNameRE.MatchString(k) {
+			return fmt.Errorf("invalid label name %q", k)
+		}
+		if v.Regexp == nil {
+			return fmt.Errorf("invalid regexp value for %q", k)
+		}
+	}
+	return nil
+}
+
 // Regexp encapsulates a regexp.Regexp and makes it YAML marshalable.
 type Regexp struct {
 	*regexp.Regexp

config/config_test.go

@@ -16,6 +16,7 @@ package config
 import (
 	"encoding/json"
 	"net/url"
+	"os"
 	"reflect"
 	"regexp"
 	"strings"
@@ -776,3 +777,32 @@ func TestUnmarshalHostPort(t *testing.T) {
 		})
 	}
 }
+
+func TestNilRegexp(t *testing.T) {
+	for _, tc := range []struct {
+		file   string
+		errMsg string
+	}{
+		{
+			file:   "testdata/conf.nil-match_re-route.yml",
+			errMsg: "invalid_label",
+		},
+		{
+			file:   "testdata/conf.nil-source_match_re-inhibitiion.yml",
+			errMsg: "invalid_source_label",
+		},
+		{
+			file:   "testdata/conf.nil-target_match_re-inhibitiion.yml",
+			errMsg: "invalid_target_label",
+		},
+	} {
+		t.Run(tc.file, func(t *testing.T) {
+			_, err := os.Stat(tc.file)
+			require.NoError(t, err)
+
+			_, err = LoadFile(tc.file)
+			require.Error(t, err)
+			require.Contains(t, err.Error(), tc.errMsg)
+		})
+	}
+}

config/testdata/conf.nil-match_re-route.yml

@@ -0,0 +1,10 @@
+route:
+  receiver: empty
+
+  routes:
+  - match_re:
+      invalid_label:
+    receiver: empty
+
+receivers:
+- name: empty

config/testdata/conf.nil-source_match_re-inhibitiion.yml

@@ -0,0 +1,11 @@
+route:
+  receiver: empty
+
+receivers:
+- name: empty
+
+inhibit_rules:
+- source_match_re:
+    invalid_source_label:
+  target_match_re:
+    severity: critical

config/testdata/conf.nil-target_match_re-inhibitiion.yml

@@ -0,0 +1,11 @@
+route:
+  receiver: empty
+
+receivers:
+- name: empty
+
+inhibit_rules:
+- source_match:
+    severity: critical
+  target_match_re:
+    invalid_target_label: