[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, 155 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/net_softnet.go b/vendor/github.com/prometheus/procfs/net_softnet.go
new file mode 100644
index 000000000..c77085291
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/net_softnet.go
@@ -0,0 +1,155 @@
+// Copyright 2019 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"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+// For the proc file format details,
+// See:
+// * Linux 2.6.23 https://elixir.bootlin.com/linux/v2.6.23/source/net/core/dev.c#L2343
+// * Linux 2.6.39 https://elixir.bootlin.com/linux/v2.6.39/source/net/core/dev.c#L4086
+// * Linux 4.18 https://elixir.bootlin.com/linux/v4.18/source/net/core/net-procfs.c#L162
+// * Linux 5.14 https://elixir.bootlin.com/linux/v5.14/source/net/core/net-procfs.c#L169
+
+// SoftnetStat contains a single row of data from /proc/net/softnet_stat.
+type SoftnetStat struct {
+	// Number of processed packets.
+	Processed uint32
+	// Number of dropped packets.
+	Dropped uint32
+	// Number of times processing packets ran out of quota.
+	TimeSqueezed uint32
+	// Number of collision occur while obtaining device lock while transmitting.
+	CPUCollision uint32
+	// Number of times cpu woken up received_rps.
+	ReceivedRps uint32
+	// number of times flow limit has been reached.
+	FlowLimitCount uint32
+	// Softnet backlog status.
+	SoftnetBacklogLen uint32
+	// CPU id owning this softnet_data.
+	Index uint32
+	// softnet_data's Width.
+	Width int
+}
+
+var softNetProcFile = "net/softnet_stat"
+
+// NetSoftnetStat reads data from /proc/net/softnet_stat.
+func (fs FS) NetSoftnetStat() ([]SoftnetStat, error) {
+	b, err := util.ReadFileNoStat(fs.proc.Path(softNetProcFile))
+	if err != nil {
+		return nil, err
+	}
+
+	entries, err := parseSoftnet(bytes.NewReader(b))
+	if err != nil {
+		return nil, fmt.Errorf("%s: /proc/net/softnet_stat: %w", ErrFileParse, err)
+	}
+
+	return entries, nil
+}
+
+func parseSoftnet(r io.Reader) ([]SoftnetStat, error) {
+	const minColumns = 9
+
+	s := bufio.NewScanner(r)
+
+	var stats []SoftnetStat
+	cpuIndex := 0
+	for s.Scan() {
+		columns := strings.Fields(s.Text())
+		width := len(columns)
+		softnetStat := SoftnetStat{}
+
+		if width < minColumns {
+			return nil, fmt.Errorf("%w: detected %d columns, but expected at least %d", ErrFileParse, width, minColumns)
+		}
+
+		// Linux 2.6.23 https://elixir.bootlin.com/linux/v2.6.23/source/net/core/dev.c#L2347
+		if width >= minColumns {
+			us, err := parseHexUint32s(columns[0:9])
+			if err != nil {
+				return nil, err
+			}
+
+			softnetStat.Processed = us[0]
+			softnetStat.Dropped = us[1]
+			softnetStat.TimeSqueezed = us[2]
+			softnetStat.CPUCollision = us[8]
+		}
+
+		// Linux 2.6.39 https://elixir.bootlin.com/linux/v2.6.39/source/net/core/dev.c#L4086
+		if width >= 10 {
+			us, err := parseHexUint32s(columns[9:10])
+			if err != nil {
+				return nil, err
+			}
+
+			softnetStat.ReceivedRps = us[0]
+		}
+
+		// Linux 4.18 https://elixir.bootlin.com/linux/v4.18/source/net/core/net-procfs.c#L162
+		if width >= 11 {
+			us, err := parseHexUint32s(columns[10:11])
+			if err != nil {
+				return nil, err
+			}
+
+			softnetStat.FlowLimitCount = us[0]
+		}
+
+		// Linux 5.14 https://elixir.bootlin.com/linux/v5.14/source/net/core/net-procfs.c#L169
+		if width >= 13 {
+			us, err := parseHexUint32s(columns[11:13])
+			if err != nil {
+				return nil, err
+			}
+
+			softnetStat.SoftnetBacklogLen = us[0]
+			softnetStat.Index = us[1]
+		} else {
+			// For older kernels, create the Index based on the scan line number.
+			softnetStat.Index = uint32(cpuIndex)
+		}
+		softnetStat.Width = width
+		stats = append(stats, softnetStat)
+		cpuIndex++
+	}
+
+	return stats, nil
+}
+
+func parseHexUint32s(ss []string) ([]uint32, error) {
+	us := make([]uint32, 0, len(ss))
+	for _, s := range ss {
+		u, err := strconv.ParseUint(s, 16, 32)
+		if err != nil {
+			return nil, err
+		}
+
+		us = append(us, uint32(u))
+	}
+
+	return us, nil
+}