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/xfrm.go

@@ -0,0 +1,187 @@
+// Copyright 2017 Prometheus Team
+// 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"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// XfrmStat models the contents of /proc/net/xfrm_stat.
+type XfrmStat struct {
+	// All errors which are not matched by other
+	XfrmInError int
+	// No buffer is left
+	XfrmInBufferError int
+	// Header Error
+	XfrmInHdrError int
+	// No state found
+	// i.e. either inbound SPI, address, or IPSEC protocol at SA is wrong
+	XfrmInNoStates int
+	// Transformation protocol specific error
+	// e.g. SA Key is wrong
+	XfrmInStateProtoError int
+	// Transformation mode specific error
+	XfrmInStateModeError int
+	// Sequence error
+	// e.g. sequence number is out of window
+	XfrmInStateSeqError int
+	// State is expired
+	XfrmInStateExpired int
+	// State has mismatch option
+	// e.g. UDP encapsulation type is mismatched
+	XfrmInStateMismatch int
+	// State is invalid
+	XfrmInStateInvalid int
+	// No matching template for states
+	// e.g. Inbound SAs are correct but SP rule is wrong
+	XfrmInTmplMismatch int
+	// No policy is found for states
+	// e.g. Inbound SAs are correct but no SP is found
+	XfrmInNoPols int
+	// Policy discards
+	XfrmInPolBlock int
+	// Policy error
+	XfrmInPolError int
+	// All errors which are not matched by others
+	XfrmOutError int
+	// Bundle generation error
+	XfrmOutBundleGenError int
+	// Bundle check error
+	XfrmOutBundleCheckError int
+	// No state was found
+	XfrmOutNoStates int
+	// Transformation protocol specific error
+	XfrmOutStateProtoError int
+	// Transportation mode specific error
+	XfrmOutStateModeError int
+	// Sequence error
+	// i.e sequence number overflow
+	XfrmOutStateSeqError int
+	// State is expired
+	XfrmOutStateExpired int
+	// Policy discads
+	XfrmOutPolBlock int
+	// Policy is dead
+	XfrmOutPolDead int
+	// Policy Error
+	XfrmOutPolError     int
+	XfrmFwdHdrError     int
+	XfrmOutStateInvalid int
+	XfrmAcquireError    int
+}
+
+// NewXfrmStat reads the xfrm_stat statistics.
+func NewXfrmStat() (XfrmStat, error) {
+	fs, err := NewFS(DefaultMountPoint)
+	if err != nil {
+		return XfrmStat{}, err
+	}
+
+	return fs.NewXfrmStat()
+}
+
+// NewXfrmStat reads the xfrm_stat statistics from the 'proc' filesystem.
+func (fs FS) NewXfrmStat() (XfrmStat, error) {
+	file, err := os.Open(fs.Path("net/xfrm_stat"))
+	if err != nil {
+		return XfrmStat{}, err
+	}
+	defer file.Close()
+
+	var (
+		x = XfrmStat{}
+		s = bufio.NewScanner(file)
+	)
+
+	for s.Scan() {
+		fields := strings.Fields(s.Text())
+
+		if len(fields) != 2 {
+			return XfrmStat{}, fmt.Errorf(
+				"couldn't parse %s line %s", file.Name(), s.Text())
+		}
+
+		name := fields[0]
+		value, err := strconv.Atoi(fields[1])
+		if err != nil {
+			return XfrmStat{}, err
+		}
+
+		switch name {
+		case "XfrmInError":
+			x.XfrmInError = value
+		case "XfrmInBufferError":
+			x.XfrmInBufferError = value
+		case "XfrmInHdrError":
+			x.XfrmInHdrError = value
+		case "XfrmInNoStates":
+			x.XfrmInNoStates = value
+		case "XfrmInStateProtoError":
+			x.XfrmInStateProtoError = value
+		case "XfrmInStateModeError":
+			x.XfrmInStateModeError = value
+		case "XfrmInStateSeqError":
+			x.XfrmInStateSeqError = value
+		case "XfrmInStateExpired":
+			x.XfrmInStateExpired = value
+		case "XfrmInStateInvalid":
+			x.XfrmInStateInvalid = value
+		case "XfrmInTmplMismatch":
+			x.XfrmInTmplMismatch = value
+		case "XfrmInNoPols":
+			x.XfrmInNoPols = value
+		case "XfrmInPolBlock":
+			x.XfrmInPolBlock = value
+		case "XfrmInPolError":
+			x.XfrmInPolError = value
+		case "XfrmOutError":
+			x.XfrmOutError = value
+		case "XfrmInStateMismatch":
+			x.XfrmInStateMismatch = value
+		case "XfrmOutBundleGenError":
+			x.XfrmOutBundleGenError = value
+		case "XfrmOutBundleCheckError":
+			x.XfrmOutBundleCheckError = value
+		case "XfrmOutNoStates":
+			x.XfrmOutNoStates = value
+		case "XfrmOutStateProtoError":
+			x.XfrmOutStateProtoError = value
+		case "XfrmOutStateModeError":
+			x.XfrmOutStateModeError = value
+		case "XfrmOutStateSeqError":
+			x.XfrmOutStateSeqError = value
+		case "XfrmOutStateExpired":
+			x.XfrmOutStateExpired = value
+		case "XfrmOutPolBlock":
+			x.XfrmOutPolBlock = value
+		case "XfrmOutPolDead":
+			x.XfrmOutPolDead = value
+		case "XfrmOutPolError":
+			x.XfrmOutPolError = value
+		case "XfrmFwdHdrError":
+			x.XfrmFwdHdrError = value
+		case "XfrmOutStateInvalid":
+			x.XfrmOutStateInvalid = value
+		case "XfrmAcquireError":
+			x.XfrmAcquireError = value
+		}
+
+	}
+
+	return x, s.Err()
+}