caddyhttp: Remove server name from metrics

For some reason this breaks automatic HTTP->HTTPS redirects. I am not
sure why yet, but as a hotfix remove this until we understand it better.

modules/caddyhttp/app.go

@@ -226,8 +226,6 @@ func (app *App) Provision(ctx caddy.Context) error {
 		// route handler so that important security checks are done, etc.
 		primaryRoute := emptyHandler
 		if srv.Routes != nil {
-			// inject the server name for observability purposes
-			ctx.Context = contextWithServerName(ctx.Context, srvName)
 			err := srv.Routes.ProvisionHandlers(ctx)
 			if err != nil {
 				return fmt.Errorf("server %s: setting up route handlers: %v", srvName, err)

modules/caddyhttp/metrics.go

@@ -94,10 +94,6 @@ func serverNameFromContext(ctx context.Context) string {
 	return srvName
 }
 
-func contextWithServerName(ctx context.Context, serverName string) context.Context {
-	return context.WithValue(ctx, ctxKeyServerName{}, serverName)
-}
-
 type metricsInstrumentedHandler struct {
 	labels       prometheus.Labels
 	statusLabels prometheus.Labels

modules/caddyhttp/metrics_test.go

@@ -1,7 +1,6 @@
 package caddyhttp
 
 import (
-	"context"
 	"errors"
 	"net/http"
 	"net/http/httptest"
@@ -10,20 +9,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus/testutil"
 )
 
-func TestServerNameFromContext(t *testing.T) {
-	ctx := context.Background()
-	expected := "UNKNOWN"
-	if actual := serverNameFromContext(ctx); actual != expected {
-		t.Errorf("Not equal: expected %q, but got %q", expected, actual)
-	}
-
-	in := "foo"
-	ctx = contextWithServerName(ctx, in)
-	if actual := serverNameFromContext(ctx); actual != in {
-		t.Errorf("Not equal: expected %q, but got %q", in, actual)
-	}
-}
-
 func TestMetricsInstrumentedHandler(t *testing.T) {
 	handlerErr := errors.New("oh noes")
 	response := []byte("hello world!")