Resolves #84 adds support for regex mappers (#85)

* Added `regex` match_type as valid config callout in both individual mappers
    and mapper defaults
  * Added test coverage for changes
  * Updated documentation to reflect usage of `match_type` parameter and
    provide example of a raw regex match rule

README.md

@@ -161,6 +161,24 @@ mappings:
     job: "${1}_server"
 ```
 
+Another capability when using YAML configuration is the ability to define matches
+using raw regular expressions as opposed to the default globbing style of match.
+This may allow for pulling structured data from otherwise poorly named statsd
+metrics AND allow for more precise targetting of match rules. When no `match_type`
+paramter is specified the default value of `glob` will be assumed:
+
+```yaml
+mappings:
+- match: (.*)\.(.*)--(.*)\.status\.(.*)\.count
+  match_type: regex
+  labels:
+    name: "request_total"
+    hostname: "$1"
+    exec: "$2"
+    protocol: "$3"
+    code: "$4"
+```
+
 Note, that one may also set the histogram buckets.  If not set, then the default
 [Prometheus client values](https://godoc.org/github.com/prometheus/client_golang/prometheus#pkg-variables) are used: `[.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10]`. `+Inf` is added
 automatically.
@@ -169,13 +187,14 @@ automatically.
 only used when the statsd metric type is a timerand the `timer_type` is set to
 "histogram."
 
-One may also set defaults for the timer type and the buckets. These will be used
+One may also set defaults for the timer type, buckets and match_type. These will be used
 by all mappings that do not define these.
 
 ```yaml
 defaults:
   timer_type: histogram
   buckets: [.005, .01, .025, .05, .1, .25, .5, 1, 2.5 ]
+  match_type: glob
 mappings:
 # This will be a histogram using the buckets set in `defaults`.
 - match: test.timing.*.*.*

mapper.go

@@ -37,6 +37,7 @@ var (
 type mapperConfigDefaults struct {
 	TimerType timerType `yaml:"timer_type"`
 	Buckets   []float64 `yaml:"buckets"`
+	MatchType matchType `yaml:"match_type"`
 }
 
 type metricMapper struct {
@@ -51,6 +52,7 @@ type metricMapping struct {
 	Labels    prometheus.Labels `yaml:"labels"`
 	TimerType timerType         `yaml:"timer_type"`
 	Buckets   []float64         `yaml:"buckets"`
+	MatchType matchType         `yaml:"match_type"`
 }
 
 type configLoadStates int
@@ -136,14 +138,14 @@ func (m *metricMapper) initFromYAMLString(fileContents string) error {
 		n.Defaults.Buckets = prometheus.DefBuckets
 	}
 
+	if n.Defaults.MatchType == matchTypeDefault {
+		n.Defaults.MatchType = matchTypeGlob
+	}
+
 	for i := range n.Mappings {
 		currentMapping := &n.Mappings[i]
 
-		if !metricLineRE.MatchString(currentMapping.Match) {
-			return fmt.Errorf("invalid match: %s", currentMapping.Match)
-		}
-
-		// Check that label is correct.
+		// check that label is correct
 		for k, v := range currentMapping.Labels {
 			if !metricNameRE.MatchString(k) {
 				return fmt.Errorf("invalid label key: %s", k)
@@ -156,12 +158,22 @@ func (m *metricMapper) initFromYAMLString(fileContents string) error {
 		if _, ok := currentMapping.Labels["name"]; !ok {
 			return fmt.Errorf("line %d: metric mapping didn't set a metric name", i)
 		}
+		if currentMapping.MatchType == "" {
+			currentMapping.MatchType = n.Defaults.MatchType
+		}
 
-		// Translate the glob-style metric match line into a proper regex that we
-		// can use to match metrics later on.
-		metricRe := strings.Replace(currentMapping.Match, ".", "\\.", -1)
-		metricRe = strings.Replace(metricRe, "*", "([^.]+)", -1)
-		currentMapping.regex = regexp.MustCompile("^" + metricRe + "$")
+		if currentMapping.MatchType == matchTypeGlob {
+			if !metricLineRE.MatchString(currentMapping.Match) {
+				return fmt.Errorf("invalid match: %s", currentMapping.Match)
+			}
+			// Translate the glob-style metric match line into a proper regex that we
+			// can use to match metrics later on.
+			metricRe := strings.Replace(currentMapping.Match, ".", "\\.", -1)
+			metricRe = strings.Replace(metricRe, "*", "([^.]+)", -1)
+			currentMapping.regex = regexp.MustCompile("^" + metricRe + "$")
+		} else {
+			currentMapping.regex = regexp.MustCompile(currentMapping.Match)
+		}
 
 		if currentMapping.TimerType == "" {
 			currentMapping.TimerType = n.Defaults.TimerType

mapper_test.go

@@ -219,6 +219,15 @@ mappings:
     second: "$2"
     third: "$3"
     job: "$1-$2-$3"
+- match: (.*)\.(.*)-(.*)\.(.*)
+  match_type: regex
+  labels:
+    name: "proxy_requests_total"
+    job: "$1"
+    protocol: "$2"
+    endpoint: "$3"
+    result: "$4"
+
   `,
 			mappings: map[string]map[string]string{
 				"test.dispatcher.FooProcessor.send.succeeded": map[string]string{
@@ -243,6 +252,13 @@ mappings:
 					"job":    "foo-bar-",
 				},
 				"foo.bar.baz": map[string]string{},
+				"proxy-1.http-goober.success": map[string]string{
+					"name":     "proxy_requests_total",
+					"job":      "proxy-1",
+					"protocol": "http",
+					"endpoint": "goober",
+					"result":   "success",
+				},
 			},
 		},
 		// Config with bad regex reference.
@@ -333,6 +349,17 @@ mappings:
 mappings:
 - match: test.*.*
   timer_type: wrong
+  labels:
+    name: "foo"
+    `,
+			configBad: true,
+		},
+		//Config with uncompilable regex.
+		{
+			config: `---
+mappings:
+- match: *\.foo
+  match_type: regex
   labels:
     name: "foo"
     `,

match.go

@@ -0,0 +1,41 @@
+// Copyright 2013 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import "fmt"
+
+type matchType string
+
+const (
+	matchTypeGlob    matchType = "glob"
+	matchTypeRegex   matchType = "regex"
+	matchTypeDefault matchType = ""
+)
+
+func (t *matchType) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var v string
+	if err := unmarshal(&v); err != nil {
+		return err
+	}
+
+	switch matchType(v) {
+	case matchTypeRegex:
+		*t = matchTypeRegex
+	case matchTypeGlob, matchTypeDefault:
+		*t = matchTypeGlob
+	default:
+		return fmt.Errorf("invalid match type %q", v)
+	}
+	return nil
+}