middleware/proxy: absorb httpproxy (#481)

* middleware/proxy: absorb httpproxy

Move the httproxy into proxy. This adds and Exchanger interface which
is used to exchange the messages with the upstream.

The https_google upstream will re-resolve itself and update the upstream
hosts used every 300s.

* Remove and add TODO

1 files changed, 0 insertions, 32 deletions

diff --git a/middleware/httpproxy/metrics.go b/middleware/httpproxy/metrics.go
deleted file mode 100644
index c3822e523..000000000
--- a/middleware/httpproxy/metrics.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package httpproxy
-
-import (
-	"sync"
-
-	"github.com/miekg/coredns/middleware"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-// Metrics the httpproxy middleware exports.
-var (
-	RequestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_duration_milliseconds",
-		Buckets:   append(prometheus.DefBuckets, []float64{50, 100, 200, 500, 1000, 2000, 3000, 4000, 5000, 10000}...),
-		Help:      "Histogram of the time (in milliseconds) each request took.",
-	}, []string{"zone"})
-)
-
-// OnStartupMetrics sets up the metrics on startup.
-func OnStartupMetrics() error {
-	metricsOnce.Do(func() {
-		prometheus.MustRegister(RequestDuration)
-	})
-	return nil
-}
-
-var metricsOnce sync.Once
-
-const subsystem = "httpproxy"