metrics: move `metrics` up, outside `servers` (#6606)

* metrics: move `metrics`  up, outside `servers`

This change moves the metrics configuration from per-server level to a single config knob within the `http` app. Enabling `metrics` in any of the configured servers inside `http` enables metrics for all servers.

Fix #6604

Signed-off-by: Mohammed Al Sahaf <[email protected]>

* normalize domain name

---------

Signed-off-by: Mohammed Al Sahaf <[email protected]>

8 files changed, 102 insertions, 13 deletions

diff --git a/caddyconfig/httpcaddyfile/httptype.go b/caddyconfig/httpcaddyfile/httptype.go
index 4dacd9058..a238a33b4 100644
--- a/caddyconfig/httpcaddyfile/httptype.go
+++ b/caddyconfig/httpcaddyfile/httptype.go
@@ -15,6 +15,7 @@
 package httpcaddyfile
 
 import (
+	"cmp"
 	"encoding/json"
 	"fmt"
 	"net"
@@ -186,12 +187,25 @@ func (st ServerType) Setup(
 		return nil, warnings, err
 	}
 
+	// hoist the metrics config from per-server to global
+	metrics, _ := options["metrics"].(*caddyhttp.Metrics)
+	for _, s := range servers {
+		if s.Metrics != nil {
+			metrics = cmp.Or[*caddyhttp.Metrics](metrics, &caddyhttp.Metrics{})
+			metrics = &caddyhttp.Metrics{
+				PerHost: metrics.PerHost || s.Metrics.PerHost,
+			}
+			s.Metrics = nil // we don't need it anymore
+		}
+	}
+
 	// now that each server is configured, make the HTTP app
 	httpApp := caddyhttp.App{
 		HTTPPort:      tryInt(options["http_port"], &warnings),
 		HTTPSPort:     tryInt(options["https_port"], &warnings),
 		GracePeriod:   tryDuration(options["grace_period"], &warnings),
 		ShutdownDelay: tryDuration(options["shutdown_delay"], &warnings),
+		Metrics:       metrics,
 		Servers:       servers,
 	}
 
diff --git a/caddyconfig/httpcaddyfile/options.go b/caddyconfig/httpcaddyfile/options.go
index 9bae760c0..03b9ba230 100644
--- a/caddyconfig/httpcaddyfile/options.go
+++ b/caddyconfig/httpcaddyfile/options.go
@@ -24,6 +24,7 @@ import (
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig"
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
 	"github.com/caddyserver/caddy/v2/modules/caddytls"
 )
 
@@ -53,6 +54,7 @@ func init() {
 	RegisterGlobalOption("local_certs", parseOptTrue)
 	RegisterGlobalOption("key_type", parseOptSingleString)
 	RegisterGlobalOption("auto_https", parseOptAutoHTTPS)
+	RegisterGlobalOption("metrics", parseMetricsOptions)
 	RegisterGlobalOption("servers", parseServerOptions)
 	RegisterGlobalOption("ocsp_stapling", parseOCSPStaplingOptions)
 	RegisterGlobalOption("cert_lifetime", parseOptDuration)
@@ -446,6 +448,24 @@ func parseOptAutoHTTPS(d *caddyfile.Dispenser, _ any) (any, error) {
 	return val, nil
 }
 
+func unmarshalCaddyfileMetricsOptions(d *caddyfile.Dispenser) (any, error) {
+	d.Next() // consume option name
+	metrics := new(caddyhttp.Metrics)
+	for d.NextBlock(0) {
+		switch d.Val() {
+		case "per_host":
+			metrics.PerHost = true
+		default:
+			return nil, d.Errf("unrecognized servers option '%s'", d.Val())
+		}
+	}
+	return metrics, nil
+}
+
+func parseMetricsOptions(d *caddyfile.Dispenser, _ any) (any, error) {
+	return unmarshalCaddyfileMetricsOptions(d)
+}
+
 func parseServerOptions(d *caddyfile.Dispenser, _ any) (any, error) {
 	return unmarshalCaddyfileServerOptions(d)
 }
diff --git a/caddyconfig/httpcaddyfile/serveroptions.go b/caddyconfig/httpcaddyfile/serveroptions.go
index b05af47f5..40a8af209 100644
--- a/caddyconfig/httpcaddyfile/serveroptions.go
+++ b/caddyconfig/httpcaddyfile/serveroptions.go
@@ -240,6 +240,7 @@ func unmarshalCaddyfileServerOptions(d *caddyfile.Dispenser) (any, error) {
 			}
 
 		case "metrics":
+			caddy.Log().Warn("The nested 'metrics' option inside `servers` is deprecated and will be removed in the next major version. Use the global 'metrics' option instead.")
 			serverOpts.Metrics = new(caddyhttp.Metrics)
 			for nesting := d.Nesting(); d.NextBlock(nesting); {
 				switch d.Val() {
diff --git a/caddytest/integration/caddyfile_adapt/metrics_merge_options.caddyfiletest b/caddytest/integration/caddyfile_adapt/metrics_merge_options.caddyfiletest
new file mode 100644
index 000000000..946b3d0c8
--- /dev/null
+++ b/caddytest/integration/caddyfile_adapt/metrics_merge_options.caddyfiletest
@@ -0,0 +1,39 @@
+{
+	metrics
+	servers :80 {
+		metrics {
+			per_host
+		}
+	}
+}
+:80 {
+	respond "Hello"
+}
+
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":80"
+					],
+					"routes": [
+						{
+							"handle": [
+								{
+									"body": "Hello",
+									"handler": "static_response"
+								}
+							]
+						}
+					]
+				}
+			},
+			"metrics": {
+				"per_host": true
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/caddytest/integration/caddyfile_adapt/metrics_perhost.caddyfiletest b/caddytest/integration/caddyfile_adapt/metrics_perhost.caddyfiletest
index 499215515..e362cecc9 100644
--- a/caddytest/integration/caddyfile_adapt/metrics_perhost.caddyfiletest
+++ b/caddytest/integration/caddyfile_adapt/metrics_perhost.caddyfiletest
@@ -26,11 +26,11 @@
 								}
 							]
 						}
-					],
-					"metrics": {
-						"per_host": true
-					}
+					]
 				}
+			},
+			"metrics": {
+				"per_host": true
 			}
 		}
 	}
diff --git a/modules/caddyhttp/app.go b/modules/caddyhttp/app.go
index cd32e72d7..2d221265f 100644
--- a/modules/caddyhttp/app.go
+++ b/modules/caddyhttp/app.go
@@ -15,6 +15,7 @@
 package caddyhttp
 
 import (
+	"cmp"
 	"context"
 	"crypto/tls"
 	"fmt"
@@ -142,6 +143,10 @@ type App struct {
 	// affect functionality.
 	Servers map[string]*Server `json:"servers,omitempty"`
 
+	// If set, metrics observations will be enabled.
+	// This setting is EXPERIMENTAL and subject to change.
+	Metrics *Metrics `json:"metrics,omitempty"`
+
 	ctx    caddy.Context
 	logger *zap.Logger
 	tlsApp *caddytls.TLS
@@ -184,6 +189,10 @@ func (app *App) Provision(ctx caddy.Context) error {
 		return err
 	}
 
+	if app.Metrics != nil {
+		app.Metrics.init = sync.Once{}
+		app.Metrics.httpMetrics = &httpMetrics{}
+	}
 	// prepare each server
 	oldContext := ctx.Context
 	for srvName, srv := range app.Servers {
@@ -196,6 +205,15 @@ func (app *App) Provision(ctx caddy.Context) error {
 		srv.errorLogger = app.logger.Named("log.error")
 		srv.shutdownAtMu = new(sync.RWMutex)
 
+		if srv.Metrics != nil {
+			srv.logger.Warn("per-server 'metrics' is deprecated; use 'metrics' in the root 'http' app instead")
+			app.Metrics = cmp.Or[*Metrics](app.Metrics, &Metrics{
+				init:        sync.Once{},
+				httpMetrics: &httpMetrics{},
+			})
+			app.Metrics.PerHost = app.Metrics.PerHost || srv.Metrics.PerHost
+		}
+
 		// only enable access logs if configured
 		if srv.Logs != nil {
 			srv.accessLogger = app.logger.Named("log.access")
@@ -342,16 +360,11 @@ func (app *App) Provision(ctx caddy.Context) error {
 				srv.listenerWrappers = append([]caddy.ListenerWrapper{new(tlsPlaceholderWrapper)}, srv.listenerWrappers...)
 			}
 		}
-
 		// pre-compile the primary handler chain, and be sure to wrap it in our
 		// route handler so that important security checks are done, etc.
 		primaryRoute := emptyHandler
 		if srv.Routes != nil {
-			if srv.Metrics != nil {
-				srv.Metrics.init = sync.Once{}
-				srv.Metrics.httpMetrics = &httpMetrics{}
-			}
-			err := srv.Routes.ProvisionHandlers(ctx, srv.Metrics)
+			err := srv.Routes.ProvisionHandlers(ctx, app.Metrics)
 			if err != nil {
 				return fmt.Errorf("server %s: setting up route handlers: %v", srvName, err)
 			}
@@ -370,7 +383,7 @@ func (app *App) Provision(ctx caddy.Context) error {
 
 		// provision the named routes (they get compiled at runtime)
 		for name, route := range srv.NamedRoutes {
-			err := route.Provision(ctx, srv.Metrics)
+			err := route.Provision(ctx, app.Metrics)
 			if err != nil {
 				return fmt.Errorf("server %s: setting up named route '%s' handlers: %v", name, srvName, err)
 			}
diff --git a/modules/caddyhttp/metrics.go b/modules/caddyhttp/metrics.go
index 947721429..9bb97e0b4 100644
--- a/modules/caddyhttp/metrics.go
+++ b/modules/caddyhttp/metrics.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"net/http"
+	"strings"
 	"sync"
 	"time"
 
@@ -133,8 +134,8 @@ func (h *metricsInstrumentedHandler) ServeHTTP(w http.ResponseWriter, r *http.Re
 	statusLabels := prometheus.Labels{"server": server, "handler": h.handler, "method": method, "code": ""}
 
 	if h.metrics.PerHost {
-		labels["host"] = r.Host
-		statusLabels["host"] = r.Host
+		labels["host"] = strings.ToLower(r.Host)
+		statusLabels["host"] = strings.ToLower(r.Host)
 	}
 
 	inFlight := h.metrics.httpMetrics.requestInFlight.With(labels)
diff --git a/modules/caddyhttp/server.go b/modules/caddyhttp/server.go
index 96001c6f9..24fecfd88 100644
--- a/modules/caddyhttp/server.go
+++ b/modules/caddyhttp/server.go
@@ -226,6 +226,7 @@ type Server struct {
 
 	// If set, metrics observations will be enabled.
 	// This setting is EXPERIMENTAL and subject to change.
+	// DEPRECATED: Use the app-level `metrics` field.
 	Metrics *Metrics `json:"metrics,omitempty"`
 
 	name string