Prometheus endpoint (#5256)

* Add prometheus collector and route

* dep ensure -add github.com/prometheus/client_golang/prometheus

* dep ensure -update github.com/golang/protobuf

* add metrics to reserved usernames

* add comment head in metrics package

* fix style imports

* add metrics settings

* add bearer token check

* mapping metrics configs

* fix lint

* update config cheat sheet

* update conf sample, typo fix

vendor/github.com/prometheus/procfs/proc.go

@@ -0,0 +1,258 @@
+// 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 (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// Proc provides information about a running process.
+type Proc struct {
+	// The process ID.
+	PID int
+
+	fs FS
+}
+
+// Procs represents a list of Proc structs.
+type Procs []Proc
+
+func (p Procs) Len() int           { return len(p) }
+func (p Procs) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+func (p Procs) Less(i, j int) bool { return p[i].PID < p[j].PID }
+
+// Self returns a process for the current process read via /proc/self.
+func Self() (Proc, error) {
+	fs, err := NewFS(DefaultMountPoint)
+	if err != nil {
+		return Proc{}, err
+	}
+	return fs.Self()
+}
+
+// NewProc returns a process for the given pid under /proc.
+func NewProc(pid int) (Proc, error) {
+	fs, err := NewFS(DefaultMountPoint)
+	if err != nil {
+		return Proc{}, err
+	}
+	return fs.NewProc(pid)
+}
+
+// AllProcs returns a list of all currently available processes under /proc.
+func AllProcs() (Procs, error) {
+	fs, err := NewFS(DefaultMountPoint)
+	if err != nil {
+		return Procs{}, err
+	}
+	return fs.AllProcs()
+}
+
+// Self returns a process for the current process.
+func (fs FS) Self() (Proc, error) {
+	p, err := os.Readlink(fs.Path("self"))
+	if err != nil {
+		return Proc{}, err
+	}
+	pid, err := strconv.Atoi(strings.Replace(p, string(fs), "", -1))
+	if err != nil {
+		return Proc{}, err
+	}
+	return fs.NewProc(pid)
+}
+
+// NewProc returns a process for the given pid.
+func (fs FS) NewProc(pid int) (Proc, error) {
+	if _, err := os.Stat(fs.Path(strconv.Itoa(pid))); err != nil {
+		return Proc{}, err
+	}
+	return Proc{PID: pid, fs: fs}, nil
+}
+
+// AllProcs returns a list of all currently available processes.
+func (fs FS) AllProcs() (Procs, error) {
+	d, err := os.Open(fs.Path())
+	if err != nil {
+		return Procs{}, err
+	}
+	defer d.Close()
+
+	names, err := d.Readdirnames(-1)
+	if err != nil {
+		return Procs{}, fmt.Errorf("could not read %s: %s", d.Name(), err)
+	}
+
+	p := Procs{}
+	for _, n := range names {
+		pid, err := strconv.ParseInt(n, 10, 64)
+		if err != nil {
+			continue
+		}
+		p = append(p, Proc{PID: int(pid), fs: fs})
+	}
+
+	return p, nil
+}
+
+// CmdLine returns the command line of a process.
+func (p Proc) CmdLine() ([]string, error) {
+	f, err := os.Open(p.path("cmdline"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(data) < 1 {
+		return []string{}, nil
+	}
+
+	return strings.Split(string(bytes.TrimRight(data, string("\x00"))), string(byte(0))), nil
+}
+
+// Comm returns the command name of a process.
+func (p Proc) Comm() (string, error) {
+	f, err := os.Open(p.path("comm"))
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(string(data)), nil
+}
+
+// Executable returns the absolute path of the executable command of a process.
+func (p Proc) Executable() (string, error) {
+	exe, err := os.Readlink(p.path("exe"))
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+
+	return exe, err
+}
+
+// Cwd returns the absolute path to the current working directory of the process.
+func (p Proc) Cwd() (string, error) {
+	wd, err := os.Readlink(p.path("cwd"))
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+
+	return wd, err
+}
+
+// RootDir returns the absolute path to the process's root directory (as set by chroot)
+func (p Proc) RootDir() (string, error) {
+	rdir, err := os.Readlink(p.path("root"))
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+
+	return rdir, err
+}
+
+// FileDescriptors returns the currently open file descriptors of a process.
+func (p Proc) FileDescriptors() ([]uintptr, error) {
+	names, err := p.fileDescriptors()
+	if err != nil {
+		return nil, err
+	}
+
+	fds := make([]uintptr, len(names))
+	for i, n := range names {
+		fd, err := strconv.ParseInt(n, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("could not parse fd %s: %s", n, err)
+		}
+		fds[i] = uintptr(fd)
+	}
+
+	return fds, nil
+}
+
+// FileDescriptorTargets returns the targets of all file descriptors of a process.
+// If a file descriptor is not a symlink to a file (like a socket), that value will be the empty string.
+func (p Proc) FileDescriptorTargets() ([]string, error) {
+	names, err := p.fileDescriptors()
+	if err != nil {
+		return nil, err
+	}
+
+	targets := make([]string, len(names))
+
+	for i, name := range names {
+		target, err := os.Readlink(p.path("fd", name))
+		if err == nil {
+			targets[i] = target
+		}
+	}
+
+	return targets, nil
+}
+
+// FileDescriptorsLen returns the number of currently open file descriptors of
+// a process.
+func (p Proc) FileDescriptorsLen() (int, error) {
+	fds, err := p.fileDescriptors()
+	if err != nil {
+		return 0, err
+	}
+
+	return len(fds), nil
+}
+
+// MountStats retrieves statistics and configuration for mount points in a
+// process's namespace.
+func (p Proc) MountStats() ([]*Mount, error) {
+	f, err := os.Open(p.path("mountstats"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	return parseMountStats(f)
+}
+
+func (p Proc) fileDescriptors() ([]string, error) {
+	d, err := os.Open(p.path("fd"))
+	if err != nil {
+		return nil, err
+	}
+	defer d.Close()
+
+	names, err := d.Readdirnames(-1)
+	if err != nil {
+		return nil, fmt.Errorf("could not read %s: %s", d.Name(), err)
+	}
+
+	return names, nil
+}
+
+func (p Proc) path(pa ...string) string {
+	return p.fs.Path(append([]string{strconv.Itoa(p.PID)}, pa...)...)
+}