[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, 98 insertions, 0 deletions

diff --git a/vendor/github.com/prometheus/procfs/proc_cgroups.go b/vendor/github.com/prometheus/procfs/proc_cgroups.go
new file mode 100644
index 000000000..5dd493899
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/proc_cgroups.go
@@ -0,0 +1,98 @@
+// Copyright 2021 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"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+// CgroupSummary models one line from /proc/cgroups.
+// This file contains information about the controllers that are compiled into the kernel.
+//
+// Also see http://man7.org/linux/man-pages/man7/cgroups.7.html
+type CgroupSummary struct {
+	// The name of the controller. controller is also known as subsystem.
+	SubsysName string
+	// The unique ID of the cgroup hierarchy on which this controller is mounted.
+	Hierarchy int
+	// The number of control groups in this hierarchy using this controller.
+	Cgroups int
+	// This field contains the value 1 if this controller is enabled, or 0 if it has been disabled
+	Enabled int
+}
+
+// parseCgroupSummary parses each line of the /proc/cgroup file
+// Line format is `subsys_name	hierarchy	num_cgroups	enabled`.
+func parseCgroupSummaryString(CgroupSummaryStr string) (*CgroupSummary, error) {
+	var err error
+
+	fields := strings.Fields(CgroupSummaryStr)
+	// require at least 4 fields
+	if len(fields) < 4 {
+		return nil, fmt.Errorf("%w: 4+ fields required, found %d fields in cgroup info string: %s", ErrFileParse, len(fields), CgroupSummaryStr)
+	}
+
+	CgroupSummary := &CgroupSummary{
+		SubsysName: fields[0],
+	}
+	CgroupSummary.Hierarchy, err = strconv.Atoi(fields[1])
+	if err != nil {
+		return nil, fmt.Errorf("%w: Unable to parse hierarchy ID from %q", ErrFileParse, fields[1])
+	}
+	CgroupSummary.Cgroups, err = strconv.Atoi(fields[2])
+	if err != nil {
+		return nil, fmt.Errorf("%w: Unable to parse Cgroup Num from %q", ErrFileParse, fields[2])
+	}
+	CgroupSummary.Enabled, err = strconv.Atoi(fields[3])
+	if err != nil {
+		return nil, fmt.Errorf("%w: Unable to parse Enabled from %q", ErrFileParse, fields[3])
+	}
+	return CgroupSummary, nil
+}
+
+// parseCgroupSummary reads each line of the /proc/cgroup file.
+func parseCgroupSummary(data []byte) ([]CgroupSummary, error) {
+	var CgroupSummarys []CgroupSummary
+	scanner := bufio.NewScanner(bytes.NewReader(data))
+	for scanner.Scan() {
+		CgroupSummaryString := scanner.Text()
+		// ignore comment lines
+		if strings.HasPrefix(CgroupSummaryString, "#") {
+			continue
+		}
+		CgroupSummary, err := parseCgroupSummaryString(CgroupSummaryString)
+		if err != nil {
+			return nil, err
+		}
+		CgroupSummarys = append(CgroupSummarys, *CgroupSummary)
+	}
+
+	err := scanner.Err()
+	return CgroupSummarys, err
+}
+
+// CgroupSummarys returns information about current /proc/cgroups.
+func (fs FS) CgroupSummarys() ([]CgroupSummary, error) {
+	data, err := util.ReadFileNoStat(fs.proc.Path("cgroups"))
+	if err != nil {
+		return nil, err
+	}
+	return parseCgroupSummary(data)
+}