[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, 82 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/netstat.go b/vendor/github.com/prometheus/procfs/netstat.go
new file mode 100644
index 000000000..742dff453
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/netstat.go
@@ -0,0 +1,82 @@
+// 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"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// NetStat contains statistics for all the counters from one file.
+type NetStat struct {
+	Stats    map[string][]uint64
+	Filename string
+}
+
+// NetStat retrieves stats from `/proc/net/stat/`.
+func (fs FS) NetStat() ([]NetStat, error) {
+	statFiles, err := filepath.Glob(fs.proc.Path("net/stat/*"))
+	if err != nil {
+		return nil, err
+	}
+
+	var netStatsTotal []NetStat
+
+	for _, filePath := range statFiles {
+		procNetstat, err := parseNetstat(filePath)
+		if err != nil {
+			return nil, err
+		}
+		procNetstat.Filename = filepath.Base(filePath)
+
+		netStatsTotal = append(netStatsTotal, procNetstat)
+	}
+	return netStatsTotal, nil
+}
+
+// parseNetstat parses the metrics from `/proc/net/stat/` file
+// and returns a NetStat structure.
+func parseNetstat(filePath string) (NetStat, error) {
+	netStat := NetStat{
+		Stats: make(map[string][]uint64),
+	}
+	file, err := os.Open(filePath)
+	if err != nil {
+		return netStat, err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	scanner.Scan()
+
+	// First string is always a header for stats
+	var headers []string
+	headers = append(headers, strings.Fields(scanner.Text())...)
+
+	// Other strings represent per-CPU counters
+	for scanner.Scan() {
+		for num, counter := range strings.Fields(scanner.Text()) {
+			value, err := strconv.ParseUint(counter, 16, 64)
+			if err != nil {
+				return NetStat{}, err
+			}
+			netStat.Stats[headers[num]] = append(netStat.Stats[headers[num]], value)
+		}
+	}
+
+	return netStat, nil
+}