[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, 118 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/net_conntrackstat.go b/vendor/github.com/prometheus/procfs/net_conntrackstat.go
new file mode 100644
index 000000000..fdfa45611
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/net_conntrackstat.go
@@ -0,0 +1,118 @@
+// 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.
+
+package procfs
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+// A ConntrackStatEntry represents one line from net/stat/nf_conntrack
+// and contains netfilter conntrack statistics at one CPU core.
+type ConntrackStatEntry struct {
+	Entries       uint64
+	Searched      uint64
+	Found         uint64
+	New           uint64
+	Invalid       uint64
+	Ignore        uint64
+	Delete        uint64
+	DeleteList    uint64
+	Insert        uint64
+	InsertFailed  uint64
+	Drop          uint64
+	EarlyDrop     uint64
+	SearchRestart uint64
+}
+
+// ConntrackStat retrieves netfilter's conntrack statistics, split by CPU cores.
+func (fs FS) ConntrackStat() ([]ConntrackStatEntry, error) {
+	return readConntrackStat(fs.proc.Path("net", "stat", "nf_conntrack"))
+}
+
+// Parses a slice of ConntrackStatEntries from the given filepath.
+func readConntrackStat(path string) ([]ConntrackStatEntry, error) {
+	// This file is small and can be read with one syscall.
+	b, err := util.ReadFileNoStat(path)
+	if err != nil {
+		// Do not wrap this error so the caller can detect os.IsNotExist and
+		// similar conditions.
+		return nil, err
+	}
+
+	stat, err := parseConntrackStat(bytes.NewReader(b))
+	if err != nil {
+		return nil, fmt.Errorf("%s: Cannot read file: %v: %w", ErrFileRead, path, err)
+	}
+
+	return stat, nil
+}
+
+// Reads the contents of a conntrack statistics file and parses a slice of ConntrackStatEntries.
+func parseConntrackStat(r io.Reader) ([]ConntrackStatEntry, error) {
+	var entries []ConntrackStatEntry
+
+	scanner := bufio.NewScanner(r)
+	scanner.Scan()
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+		conntrackEntry, err := parseConntrackStatEntry(fields)
+		if err != nil {
+			return nil, err
+		}
+		entries = append(entries, *conntrackEntry)
+	}
+
+	return entries, nil
+}
+
+// Parses a ConntrackStatEntry from given array of fields.
+func parseConntrackStatEntry(fields []string) (*ConntrackStatEntry, error) {
+	entries, err := util.ParseHexUint64s(fields)
+	if err != nil {
+		return nil, fmt.Errorf("%s: Cannot parse entry: %d: %w", ErrFileParse, entries, err)
+	}
+	numEntries := len(entries)
+	if numEntries < 16 || numEntries > 17 {
+		return nil,
+			fmt.Errorf("%w: invalid conntrackstat entry, invalid number of fields: %d", ErrFileParse, numEntries)
+	}
+
+	stats := &ConntrackStatEntry{
+		Entries:      *entries[0],
+		Searched:     *entries[1],
+		Found:        *entries[2],
+		New:          *entries[3],
+		Invalid:      *entries[4],
+		Ignore:       *entries[5],
+		Delete:       *entries[6],
+		DeleteList:   *entries[7],
+		Insert:       *entries[8],
+		InsertFailed: *entries[9],
+		Drop:         *entries[10],
+		EarlyDrop:    *entries[11],
+	}
+
+	// Ignore missing search_restart on Linux < 2.6.35.
+	if numEntries == 17 {
+		stats.SearchRestart = *entries[16]
+	}
+
+	return stats, nil
+}