TUN-5749: Refactor cloudflared to pave way for reconfigurable ingress

- Split origin into supervisor and proxy packages
- Create configManager to handle dynamic config

proxy/metrics.go

@@ -0,0 +1,64 @@
+package proxy
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/cloudflare/cloudflared/connection"
+)
+
+// Metrics uses connection.MetricsNamespace(aka cloudflared) as namespace and connection.TunnelSubsystem
+// (tunnel) as subsystem to keep them consistent with the previous qualifier.
+
+var (
+	totalRequests = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: connection.MetricsNamespace,
+			Subsystem: connection.TunnelSubsystem,
+			Name:      "total_requests",
+			Help:      "Amount of requests proxied through all the tunnels",
+		},
+	)
+	concurrentRequests = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: connection.MetricsNamespace,
+			Subsystem: connection.TunnelSubsystem,
+			Name:      "concurrent_requests_per_tunnel",
+			Help:      "Concurrent requests proxied through each tunnel",
+		},
+	)
+	responseByCode = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: connection.MetricsNamespace,
+			Subsystem: connection.TunnelSubsystem,
+			Name:      "response_by_code",
+			Help:      "Count of responses by HTTP status code",
+		},
+		[]string{"status_code"},
+	)
+	requestErrors = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: connection.MetricsNamespace,
+			Subsystem: connection.TunnelSubsystem,
+			Name:      "request_errors",
+			Help:      "Count of error proxying to origin",
+		},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(
+		totalRequests,
+		concurrentRequests,
+		responseByCode,
+		requestErrors,
+	)
+}
+
+func incrementRequests() {
+	totalRequests.Inc()
+	concurrentRequests.Inc()
+}
+
+func decrementConcurrentRequests() {
+	concurrentRequests.Dec()
+}