initial prototype

README.md

@@ -1,2 +1,26 @@
-caddy-dogstatsd
+caddy dogstatsd
 ===============
+
+A [Caddy](https://caddyserver.com/) plugin for reporting metrics to [Datadog](https://datadoghq.com).
+
+## Installation
+
+## Configuration
+
+```
+dogstatsd [{host:port} [samplerate]]
+```
+
+```
+dogstatsd {
+  host {host:port}
+  samplerate {samplerate}
+  namespace {namespace}
+  tags {name:value} [{name:value}...]
+}
+```
+
+## Metrics
+
+caddy.response.count - counter - number of requests handled
+caddy.response.time - histogram - milliseconds spent handling request

handler.go

@@ -0,0 +1,50 @@
+package caddydogstatsd
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/datadog/datadog-go/statsd"
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+)
+
+// DogstatsdHandler is a middleware handler for reporting dogstatsd metrics on requests
+type DogstatsdHandler struct {
+	Client     *statsd.Client
+	SampleRate float64
+	Next       httpserver.Handler
+}
+
+// ServeHTTP is the middleware handler which will emit dogstatsd metrics after handling a request
+func (h DogstatsdHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
+	// If we do not have a statsd.Client configured, then skip any processing
+	if h.Client == nil {
+		return h.Next.ServeHTTP(w, r)
+	}
+
+	// Grab the request start time
+	var start time.Time
+	start = time.Now()
+
+	// Handle the request
+	var code int
+	var err error
+	code, err = h.Next.ServeHTTP(w, r)
+
+	// Grab the request durection in Milliseconds
+	var elapsed time.Duration
+	var elapsedMS float64
+	elapsed = time.Since(start)
+	elapsedMS = float64(elapsed.Nanoseconds()) / float64(time.Millisecond)
+
+	// Report our request metrics to dogstatsd
+	var client statsd.Client
+	client = *h.Client
+	var extraTags = []string{
+		fmt.Sprintf("status_code:%d", code),
+	}
+	client.Count("caddy.response.count", 1, extraTags, h.SampleRate)
+	client.TimeInMilliseconds("caddy.response.time", elapsedMS, extraTags, h.SampleRate)
+	return code, err
+}

setup.go

@@ -0,0 +1,111 @@
+package caddydogstatsd
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/datadog/datadog-go/statsd"
+	"github.com/mholt/caddy"
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+)
+
+func init() {
+  // register our plugin with Caddy
+	caddy.RegisterPlugin("dogstatsd", caddy.Plugin{
+		ServerType: "http",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	for c.Next() {
+    // only parse if the initial directive is "dogstatsd"
+		if c.Val() != "dogstatsd" {
+			continue
+		}
+
+    // default config values
+		var namespace = ""
+		var host = "127.0.0.1:8125"
+		var globalTags = []string{}
+		var sampleRate = 1.0
+
+    // if we have a block, then parse that
+    // e.g.
+    //   dogstatsd {
+    //     host 127.0.0.1:8125
+    //   }
+		for c.NextBlock() {
+      // each line if of the format `{key} {arg} [{arg}...]`
+			var key string
+			key = c.Val()
+
+			var args []string
+			args = c.RemainingArgs()
+      // we expect every directive to have at least 1 argument
+			if len(args) == 0 {
+				return c.ArgErr()
+			}
+
+      // parse directives
+			switch key {
+			case "host":
+				host = args[0]
+			case "samplerate":
+				var err error
+				sampleRate, err = strconv.ParseFloat(args[0], 64)
+				if err != nil {
+					return c.SyntaxErr(fmt.Sprintf("expected float for \"samplerate\", instead found \"%s\"", args[0]))
+				}
+			case "namespace":
+				namespace = args[0]
+				if !strings.HasSuffix(namespace, ".") {
+					namespace += "."
+				}
+			case "tags":
+				globalTags = args
+			default:
+				return c.SyntaxErr(fmt.Sprintf("expected one of \"host\", \"samplerate\", \"namespace\", \"tags\", instead found \"%s\"", key))
+			}
+		}
+
+    // handle non-block configuration
+    // e.g.
+    //   dogstatsd [{host:port} [{samplerate}]]
+		if c.NextArg() {
+			var args []string
+			args = c.RemainingArgs()
+			if len(args) > 0 {
+				host = args[0]
+			}
+			if len(args) > 1 {
+				var err error
+				sampleRate, err = strconv.ParseFloat(args[1], 64)
+				if err != nil {
+					return c.SyntaxErr(fmt.Sprintf("expected float for \"samplerate\", instead found \"%s\"", args[1]))
+				}
+			}
+		}
+
+    // add our middleware
+		var cfg *httpserver.SiteConfig
+		cfg = httpserver.GetConfig(c)
+		cfg.AddMiddleware(func(next httpserver.Handler) httpserver.Handler {
+			var client *statsd.Client
+			var err error
+			client, err = statsd.New(host)
+			if err == nil {
+				client.Namespace = namespace
+				client.Tags = globalTags
+			}
+
+			return DogstatsdHandler{
+				Client:     client,
+				SampleRate: sampleRate,
+				Next:       next,
+			}
+		})
+	}
+	return nil
+}