p2.7: prometheus /metrics

Default GET /metrics is Prometheus text; JSON stays at /metrics.json
and ?format=json. :8443 needs the metrics caller bearer; loopback
stays open. Restricted callers have no per-caller series and no
tavily:restricted gauge.

vendor/github.com/prometheus/procfs/kernel_hung.go

@@ -0,0 +1,44 @@
+// Copyright The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !windows
+
+package procfs
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+// KernelHung contains information about to the kernel's hung_task_detect_count number.
+type KernelHung struct {
+	// Indicates the total number of tasks that have been detected as hung since the system boot.
+	// This file shows up if `CONFIG_DETECT_HUNG_TASK` is enabled.
+	HungTaskDetectCount *uint64
+}
+
+// KernelHung returns values from /proc/sys/kernel/hung_task_detect_count.
+func (fs FS) KernelHung() (KernelHung, error) {
+	data, err := os.ReadFile(fs.proc.Path("sys", "kernel", "hung_task_detect_count"))
+	if err != nil {
+		return KernelHung{}, err
+	}
+	val, err := strconv.ParseUint(strings.TrimSpace(string(data)), 10, 64)
+	if err != nil {
+		return KernelHung{}, err
+	}
+	return KernelHung{
+		HungTaskDetectCount: &val,
+	}, nil
+}