[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, 266 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/mdstat.go b/vendor/github.com/prometheus/procfs/mdstat.go
new file mode 100644
index 000000000..fdd4b9544
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/mdstat.go
@@ -0,0 +1,266 @@
+// Copyright 2018 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 (
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	statusLineRE         = regexp.MustCompile(`(\d+) blocks .*\[(\d+)/(\d+)\] \[([U_]+)\]`)
+	recoveryLineBlocksRE = regexp.MustCompile(`\((\d+)/\d+\)`)
+	recoveryLinePctRE    = regexp.MustCompile(`= (.+)%`)
+	recoveryLineFinishRE = regexp.MustCompile(`finish=(.+)min`)
+	recoveryLineSpeedRE  = regexp.MustCompile(`speed=(.+)[A-Z]`)
+	componentDeviceRE    = regexp.MustCompile(`(.*)\[\d+\]`)
+)
+
+// MDStat holds info parsed from /proc/mdstat.
+type MDStat struct {
+	// Name of the device.
+	Name string
+	// activity-state of the device.
+	ActivityState string
+	// Number of active disks.
+	DisksActive int64
+	// Total number of disks the device requires.
+	DisksTotal int64
+	// Number of failed disks.
+	DisksFailed int64
+	// Number of "down" disks. (the _ indicator in the status line)
+	DisksDown int64
+	// Spare disks in the device.
+	DisksSpare int64
+	// Number of blocks the device holds.
+	BlocksTotal int64
+	// Number of blocks on the device that are in sync.
+	BlocksSynced int64
+	// progress percentage of current sync
+	BlocksSyncedPct float64
+	// estimated finishing time for current sync (in minutes)
+	BlocksSyncedFinishTime float64
+	// current sync speed (in Kilobytes/sec)
+	BlocksSyncedSpeed float64
+	// Name of md component devices
+	Devices []string
+}
+
+// MDStat parses an mdstat-file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.  More information available here:
+// https://raid.wiki.kernel.org/index.php/Mdstat
+func (fs FS) MDStat() ([]MDStat, error) {
+	data, err := os.ReadFile(fs.proc.Path("mdstat"))
+	if err != nil {
+		return nil, err
+	}
+	mdstat, err := parseMDStat(data)
+	if err != nil {
+		return nil, fmt.Errorf("%s: Cannot parse %v: %w", ErrFileParse, fs.proc.Path("mdstat"), err)
+	}
+	return mdstat, nil
+}
+
+// parseMDStat parses data from mdstat file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.
+func parseMDStat(mdStatData []byte) ([]MDStat, error) {
+	mdStats := []MDStat{}
+	lines := strings.Split(string(mdStatData), "\n")
+
+	for i, line := range lines {
+		if strings.TrimSpace(line) == "" || line[0] == ' ' ||
+			strings.HasPrefix(line, "Personalities") ||
+			strings.HasPrefix(line, "unused") {
+			continue
+		}
+
+		deviceFields := strings.Fields(line)
+		if len(deviceFields) < 3 {
+			return nil, fmt.Errorf("%s: Expected 3+ lines, got %q", ErrFileParse, line)
+		}
+		mdName := deviceFields[0] // mdx
+		state := deviceFields[2]  // active or inactive
+
+		if len(lines) <= i+3 {
+			return nil, fmt.Errorf("%w: Too few lines for md device: %q", ErrFileParse, mdName)
+		}
+
+		// Failed disks have the suffix (F) & Spare disks have the suffix (S).
+		fail := int64(strings.Count(line, "(F)"))
+		spare := int64(strings.Count(line, "(S)"))
+		active, total, down, size, err := evalStatusLine(lines[i], lines[i+1])
+
+		if err != nil {
+			return nil, fmt.Errorf("%s: Cannot parse md device lines: %v: %w", ErrFileParse, active, err)
+		}
+
+		syncLineIdx := i + 2
+		if strings.Contains(lines[i+2], "bitmap") { // skip bitmap line
+			syncLineIdx++
+		}
+
+		// If device is syncing at the moment, get the number of currently
+		// synced bytes, otherwise that number equals the size of the device.
+		syncedBlocks := size
+		speed := float64(0)
+		finish := float64(0)
+		pct := float64(0)
+		recovering := strings.Contains(lines[syncLineIdx], "recovery")
+		resyncing := strings.Contains(lines[syncLineIdx], "resync")
+		checking := strings.Contains(lines[syncLineIdx], "check")
+
+		// Append recovery and resyncing state info.
+		if recovering || resyncing || checking {
+			if recovering {
+				state = "recovering"
+			} else if checking {
+				state = "checking"
+			} else {
+				state = "resyncing"
+			}
+
+			// Handle case when resync=PENDING or resync=DELAYED.
+			if strings.Contains(lines[syncLineIdx], "PENDING") ||
+				strings.Contains(lines[syncLineIdx], "DELAYED") {
+				syncedBlocks = 0
+			} else {
+				syncedBlocks, pct, finish, speed, err = evalRecoveryLine(lines[syncLineIdx])
+				if err != nil {
+					return nil, fmt.Errorf("%s: Cannot parse sync line in md device: %q: %w", ErrFileParse, mdName, err)
+				}
+			}
+		}
+
+		mdStats = append(mdStats, MDStat{
+			Name:                   mdName,
+			ActivityState:          state,
+			DisksActive:            active,
+			DisksFailed:            fail,
+			DisksDown:              down,
+			DisksSpare:             spare,
+			DisksTotal:             total,
+			BlocksTotal:            size,
+			BlocksSynced:           syncedBlocks,
+			BlocksSyncedPct:        pct,
+			BlocksSyncedFinishTime: finish,
+			BlocksSyncedSpeed:      speed,
+			Devices:                evalComponentDevices(deviceFields),
+		})
+	}
+
+	return mdStats, nil
+}
+
+func evalStatusLine(deviceLine, statusLine string) (active, total, down, size int64, err error) {
+	statusFields := strings.Fields(statusLine)
+	if len(statusFields) < 1 {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected statusline %q: %w", ErrFileParse, statusLine, err)
+	}
+
+	sizeStr := statusFields[0]
+	size, err = strconv.ParseInt(sizeStr, 10, 64)
+	if err != nil {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected statusline %q: %w", ErrFileParse, statusLine, err)
+	}
+
+	if strings.Contains(deviceLine, "raid0") || strings.Contains(deviceLine, "linear") {
+		// In the device deviceLine, only disks have a number associated with them in [].
+		total = int64(strings.Count(deviceLine, "["))
+		return total, total, 0, size, nil
+	}
+
+	if strings.Contains(deviceLine, "inactive") {
+		return 0, 0, 0, size, nil
+	}
+
+	matches := statusLineRE.FindStringSubmatch(statusLine)
+	if len(matches) != 5 {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Could not fild all substring matches %s: %w", ErrFileParse, statusLine, err)
+	}
+
+	total, err = strconv.ParseInt(matches[2], 10, 64)
+	if err != nil {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected statusline %q: %w", ErrFileParse, statusLine, err)
+	}
+
+	active, err = strconv.ParseInt(matches[3], 10, 64)
+	if err != nil {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected active %d: %w", ErrFileParse, active, err)
+	}
+	down = int64(strings.Count(matches[4], "_"))
+
+	return active, total, down, size, nil
+}
+
+func evalRecoveryLine(recoveryLine string) (syncedBlocks int64, pct float64, finish float64, speed float64, err error) {
+	matches := recoveryLineBlocksRE.FindStringSubmatch(recoveryLine)
+	if len(matches) != 2 {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected recoveryLine %s: %w", ErrFileParse, recoveryLine, err)
+	}
+
+	syncedBlocks, err = strconv.ParseInt(matches[1], 10, 64)
+	if err != nil {
+		return 0, 0, 0, 0, fmt.Errorf("%s: Unexpected parsing of recoveryLine %q: %w", ErrFileParse, recoveryLine, err)
+	}
+
+	// Get percentage complete
+	matches = recoveryLinePctRE.FindStringSubmatch(recoveryLine)
+	if len(matches) != 2 {
+		return syncedBlocks, 0, 0, 0, fmt.Errorf("%w: Unexpected recoveryLine matching percentage %s", ErrFileParse, recoveryLine)
+	}
+	pct, err = strconv.ParseFloat(strings.TrimSpace(matches[1]), 64)
+	if err != nil {
+		return syncedBlocks, 0, 0, 0, fmt.Errorf("%w: Error parsing float from recoveryLine %q", ErrFileParse, recoveryLine)
+	}
+
+	// Get time expected left to complete
+	matches = recoveryLineFinishRE.FindStringSubmatch(recoveryLine)
+	if len(matches) != 2 {
+		return syncedBlocks, pct, 0, 0, fmt.Errorf("%w: Unexpected recoveryLine matching est. finish time: %s", ErrFileParse, recoveryLine)
+	}
+	finish, err = strconv.ParseFloat(matches[1], 64)
+	if err != nil {
+		return syncedBlocks, pct, 0, 0, fmt.Errorf("%w: Unable to parse float from recoveryLine: %q", ErrFileParse, recoveryLine)
+	}
+
+	// Get recovery speed
+	matches = recoveryLineSpeedRE.FindStringSubmatch(recoveryLine)
+	if len(matches) != 2 {
+		return syncedBlocks, pct, finish, 0, fmt.Errorf("%w: Unexpected recoveryLine value: %s", ErrFileParse, recoveryLine)
+	}
+	speed, err = strconv.ParseFloat(matches[1], 64)
+	if err != nil {
+		return syncedBlocks, pct, finish, 0, fmt.Errorf("%s: Error parsing float from recoveryLine: %q: %w", ErrFileParse, recoveryLine, err)
+	}
+
+	return syncedBlocks, pct, finish, speed, nil
+}
+
+func evalComponentDevices(deviceFields []string) []string {
+	mdComponentDevices := make([]string, 0)
+	if len(deviceFields) > 3 {
+		for _, field := range deviceFields[4:] {
+			match := componentDeviceRE.FindStringSubmatch(field)
+			if match == nil {
+				continue
+			}
+			mdComponentDevices = append(mdComponentDevices, match[1])
+		}
+	}
+
+	return mdComponentDevices
+}