[feature] Initial Prometheus metrics implementation (#2334)

* feat: Initial OTEL metrics

* docs: add metrics documentation

* fix: metrics endpoint conditional check

* feat: metrics endpoint basic auth

* fix: make metrics-auth-enabled default false

* fix: go fmt helpers.gen.go

* fix: add metric-related env vars to envparsing.sh

* fix: metrics docs

* fix: metrics related stuff in envparsing.sh

* fix: metrics docs

* chore: metrics docs wording

* fix: metrics stuff in envparsing?

* bump otel versions

---------

Co-authored-by: Tsuribori <user@acertaindebian>
Co-authored-by: Tsuribori <none@example.org>
Co-authored-by: tsmethurst <tobi.smethurst@protonmail.com>

1 files changed, 166 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/proc_smaps.go b/vendor/github.com/prometheus/procfs/proc_smaps.go
new file mode 100644
index 000000000..ad8785a40
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/proc_smaps.go
@@ -0,0 +1,166 @@
+// Copyright 2020 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
+// +build !windows
+
+package procfs
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+var (
+	// match the header line before each mapped zone in `/proc/pid/smaps`.
+	procSMapsHeaderLine = regexp.MustCompile(`^[a-f0-9].*$`)
+)
+
+type ProcSMapsRollup struct {
+	// Amount of the mapping that is currently resident in RAM.
+	Rss uint64
+	// Process's proportional share of this mapping.
+	Pss uint64
+	// Size in bytes of clean shared pages.
+	SharedClean uint64
+	// Size in bytes of dirty shared pages.
+	SharedDirty uint64
+	// Size in bytes of clean private pages.
+	PrivateClean uint64
+	// Size in bytes of dirty private pages.
+	PrivateDirty uint64
+	// Amount of memory currently marked as referenced or accessed.
+	Referenced uint64
+	// Amount of memory that does not belong to any file.
+	Anonymous uint64
+	// Amount would-be-anonymous memory currently on swap.
+	Swap uint64
+	// Process's proportional memory on swap.
+	SwapPss uint64
+}
+
+// ProcSMapsRollup reads from /proc/[pid]/smaps_rollup to get summed memory information of the
+// process.
+//
+// If smaps_rollup does not exists (require kernel >= 4.15), the content of /proc/pid/smaps will
+// we read and summed.
+func (p Proc) ProcSMapsRollup() (ProcSMapsRollup, error) {
+	data, err := util.ReadFileNoStat(p.path("smaps_rollup"))
+	if err != nil && os.IsNotExist(err) {
+		return p.procSMapsRollupManual()
+	}
+	if err != nil {
+		return ProcSMapsRollup{}, err
+	}
+
+	lines := strings.Split(string(data), "\n")
+	smaps := ProcSMapsRollup{}
+
+	// skip first line which don't contains information we need
+	lines = lines[1:]
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+
+		if err := smaps.parseLine(line); err != nil {
+			return ProcSMapsRollup{}, err
+		}
+	}
+
+	return smaps, nil
+}
+
+// Read /proc/pid/smaps and do the roll-up in Go code.
+func (p Proc) procSMapsRollupManual() (ProcSMapsRollup, error) {
+	file, err := os.Open(p.path("smaps"))
+	if err != nil {
+		return ProcSMapsRollup{}, err
+	}
+	defer file.Close()
+
+	smaps := ProcSMapsRollup{}
+	scan := bufio.NewScanner(file)
+
+	for scan.Scan() {
+		line := scan.Text()
+
+		if procSMapsHeaderLine.MatchString(line) {
+			continue
+		}
+
+		if err := smaps.parseLine(line); err != nil {
+			return ProcSMapsRollup{}, err
+		}
+	}
+
+	return smaps, nil
+}
+
+func (s *ProcSMapsRollup) parseLine(line string) error {
+	kv := strings.SplitN(line, ":", 2)
+	if len(kv) != 2 {
+		fmt.Println(line)
+		return errors.New("invalid net/dev line, missing colon")
+	}
+
+	k := kv[0]
+	if k == "VmFlags" {
+		return nil
+	}
+
+	v := strings.TrimSpace(kv[1])
+	v = strings.TrimRight(v, " kB")
+
+	vKBytes, err := strconv.ParseUint(v, 10, 64)
+	if err != nil {
+		return err
+	}
+	vBytes := vKBytes * 1024
+
+	s.addValue(k, vBytes)
+
+	return nil
+}
+
+func (s *ProcSMapsRollup) addValue(k string, vUintBytes uint64) {
+	switch k {
+	case "Rss":
+		s.Rss += vUintBytes
+	case "Pss":
+		s.Pss += vUintBytes
+	case "Shared_Clean":
+		s.SharedClean += vUintBytes
+	case "Shared_Dirty":
+		s.SharedDirty += vUintBytes
+	case "Private_Clean":
+		s.PrivateClean += vUintBytes
+	case "Private_Dirty":
+		s.PrivateDirty += vUintBytes
+	case "Referenced":
+		s.Referenced += vUintBytes
+	case "Anonymous":
+		s.Anonymous += vUintBytes
+	case "Swap":
+		s.Swap += vUintBytes
+	case "SwapPss":
+		s.SwapPss += vUintBytes
+	}
+}