Add input plugin for Fail2ban (influxdata#2875)

plugins/inputs/all/all.go

@@ -21,6 +21,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/dovecot"
 	_ "github.com/influxdata/telegraf/plugins/inputs/elasticsearch"
 	_ "github.com/influxdata/telegraf/plugins/inputs/exec"
+	_ "github.com/influxdata/telegraf/plugins/inputs/fail2ban"
 	_ "github.com/influxdata/telegraf/plugins/inputs/filestat"
 	_ "github.com/influxdata/telegraf/plugins/inputs/graylog"
 	_ "github.com/influxdata/telegraf/plugins/inputs/haproxy"

plugins/inputs/fail2ban/README.md

@@ -0,0 +1,60 @@
+# Fail2ban Plugin
+
+The fail2ban plugin gathers counts of failed and banned ip addresses from fail2ban.
+
+This plugin run fail2ban-client command, and fail2ban-client require root access.
+You have to grant telegraf to run fail2ban-client:
+
+- Run telegraf as root. (deprecate)
+- Configure sudo to grant telegraf to fail2ban-client.
+
+### Using sudo
+
+You may edit your sudo configuration with the following:
+
+``` sudo
+telegraf ALL=(root) NOPASSWD: /usr/bin/fail2ban-client status *
+```
+
+### Configuration:
+
+``` toml
+# Read metrics from fail2ban.
+[[inputs.fail2ban]]
+  ## fail2ban-client require root access.
+  ## Setting 'use_sudo' to true will make use of sudo to run fail2ban-client.
+  ## Users must configure sudo to allow telegraf user to run fail2ban-client with no password.
+  ## This plugin run only "fail2ban-client status".
+  use_sudo = false
+```
+
+### Measurements & Fields:
+
+- fail2ban
+  - failed (integer, count)
+  - banned (integer, count)
+
+### Tags:
+
+- All measurements have the following tags:
+  - jail
+
+### Example Output:
+
+```
+# fail2ban-client status sshd
+Status for the jail: sshd
+|- Filter
+|  |- Currently failed: 5
+|  |- Total failed:     20
+|  `- File list:        /var/log/secure
+`- Actions
+   |- Currently banned: 2
+   |- Total banned:     10
+   `- Banned IP list:   192.168.0.1 192.168.0.2
+```
+
+```
+$ ./telegraf --config telegraf.conf --input-filter fail2ban --test
+fail2ban,jail=sshd failed=5i,banned=2i 1495868667000000000
+```

plugins/inputs/fail2ban/fail2ban.go

@@ -0,0 +1,135 @@
+// +build linux
+
+package fail2ban
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+	"strconv"
+)
+
+var (
+	execCommand = exec.Command // execCommand is used to mock commands in tests.
+)
+
+type Fail2ban struct {
+	path    string
+	UseSudo bool
+}
+
+var sampleConfig = `
+  ## fail2ban-client require root access.
+  ## Setting 'use_sudo' to true will make use of sudo to run fail2ban-client.
+  ## Users must configure sudo to allow telegraf user to run fail2ban-client with no password.
+  ## This plugin run only "fail2ban-client status".
+  use_sudo = false
+`
+
+var metricsTargets = []struct {
+	target string
+	field  string
+}{
+	{
+		target: "Currently failed:",
+		field:  "failed",
+	},
+	{
+		target: "Currently banned:",
+		field:  "banned",
+	},
+}
+
+func (f *Fail2ban) Description() string {
+	return "Read metrics from fail2ban."
+}
+
+func (f *Fail2ban) SampleConfig() string {
+	return sampleConfig
+}
+
+func (f *Fail2ban) Gather(acc telegraf.Accumulator) error {
+	if len(f.path) == 0 {
+		return errors.New("fail2ban-client not found: verify that fail2ban is installed and that fail2ban-client is in your PATH")
+	}
+
+	name := f.path
+	var arg []string
+
+	if f.UseSudo {
+		name = "sudo"
+		arg = append(arg, f.path)
+	}
+
+	args := append(arg, "status")
+
+	cmd := execCommand(name, args...)
+	out, err := cmd.Output()
+	if err != nil {
+		return fmt.Errorf("failed to run command %s: %s - %s", strings.Join(cmd.Args, " "), err, string(out))
+	}
+	lines := strings.Split(string(out), "\n")
+	const targetString = "Jail list:"
+	var jails []string
+	for _, line := range lines {
+		idx := strings.LastIndex(line, targetString)
+		if idx < 0 {
+			// not target line, skip.
+			continue
+		}
+		jails = strings.Split(strings.TrimSpace(line[idx+len(targetString):]), ", ")
+		break
+	}
+
+	for _, jail := range jails {
+		fields := make(map[string]interface{})
+		args := append(arg, "status", jail)
+		cmd := execCommand(name, args...)
+		out, err := cmd.Output()
+		if err != nil {
+			return fmt.Errorf("failed to run command %s: %s - %s", strings.Join(cmd.Args, " "), err, string(out))
+		}
+
+		lines := strings.Split(string(out), "\n")
+		for _, line := range lines {
+			key, value := extractCount(line)
+			if key != "" {
+				fields[key] = value
+			}
+		}
+		acc.AddFields("fail2ban", fields, map[string]string{"jail": jail})
+	}
+	return nil
+}
+
+func extractCount(line string) (string, int) {
+	for _, metricsTarget := range metricsTargets {
+		idx := strings.LastIndex(line, metricsTarget.target)
+		if idx < 0 {
+			continue
+		}
+		ban := strings.TrimSpace(line[idx+len(metricsTarget.target):])
+		banCount, err := strconv.Atoi(ban)
+		if err != nil {
+			return "", -1
+		}
+		return metricsTarget.field, banCount
+	}
+	return "", -1
+}
+
+func init() {
+	f := Fail2ban{}
+	path, _ := exec.LookPath("fail2ban-client")
+	if len(path) > 0 {
+		f.path = path
+	}
+	inputs.Add("fail2ban", func() telegraf.Input {
+		f := f
+		return &f
+	})
+}

plugins/inputs/fail2ban/fail2ban_nolinux.go

@@ -0,0 +1,3 @@
+// +build !linux
+
+package fail2ban

plugins/inputs/fail2ban/fail2ban_test.go

@@ -0,0 +1,125 @@
+package fail2ban
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+)
+
+// By all rights, we should use `string literal`, but the string contains "`".
+var execStatusOutput = "Status\n" +
+	"|- Number of jail:\t3\n" +
+	"`- Jail list:\tdovecot, postfix, sshd"
+var execStatusDovecotOutput = "Status for the jail: dovecot\n" +
+	"|- Filter\n" +
+	"|  |- Currently failed:\t11\n" +
+	"|  |- Total failed:\t22\n" +
+	"|  `- File list:\t/var/log/maillog\n" +
+	"`- Actions\n" +
+	"   |- Currently banned:\t0\n" +
+	"   |- Total banned:\t100\n" +
+	"   `- Banned IP list:"
+var execStatusPostfixOutput = "Status for the jail: postfix\n" +
+	"|- Filter\n" +
+	"|  |- Currently failed:\t4\n" +
+	"|  |- Total failed:\t10\n" +
+	"|  `- File list:\t/var/log/maillog\n" +
+	"`- Actions\n" +
+	"   |- Currently banned:\t3\n" +
+	"   |- Total banned:\t60\n" +
+	"   `- Banned IP list:\t192.168.10.1 192.168.10.3"
+var execStatusSshdOutput = "Status for the jail: sshd\n" +
+	"|- Filter\n" +
+	"|  |- Currently failed:\t0\n" +
+	"|  |- Total failed:\t5\n" +
+	"|  `- File list:\t/var/log/secure\n" +
+	"`- Actions\n" +
+	"   |- Currently banned:\t2\n" +
+	"   |- Total banned:\t50\n" +
+	"   `- Banned IP list:\t192.168.0.1 192.168.1.1"
+
+func TestGather(t *testing.T) {
+	f := Fail2ban{
+		path: "/usr/bin/fail2ban-client",
+	}
+
+	execCommand = fakeExecCommand
+	defer func() { execCommand = exec.Command }()
+	var acc testutil.Accumulator
+	err := f.Gather(&acc)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	fields1 := map[string]interface{}{
+		"banned": 2,
+		"failed": 0,
+	}
+	tags1 := map[string]string{
+		"jail": "sshd",
+	}
+
+	fields2 := map[string]interface{}{
+		"banned": 3,
+		"failed": 4,
+	}
+	tags2 := map[string]string{
+		"jail": "postfix",
+	}
+
+	fields3 := map[string]interface{}{
+		"banned": 0,
+		"failed": 11,
+	}
+	tags3 := map[string]string{
+		"jail": "dovecot",
+	}
+
+	acc.AssertContainsTaggedFields(t, "fail2ban", fields1, tags1)
+	acc.AssertContainsTaggedFields(t, "fail2ban", fields2, tags2)
+	acc.AssertContainsTaggedFields(t, "fail2ban", fields3, tags3)
+}
+
+func fakeExecCommand(command string, args ...string) *exec.Cmd {
+	cs := []string{"-test.run=TestHelperProcess", "--", command}
+	cs = append(cs, args...)
+	cmd := exec.Command(os.Args[0], cs...)
+	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
+	return cmd
+}
+
+func TestHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	args := os.Args
+	cmd, args := args[3], args[4:]
+
+	if !strings.HasSuffix(cmd, "fail2ban-client") {
+		fmt.Fprint(os.Stdout, "command not found")
+		os.Exit(1)
+	}
+
+	if len(args) == 1 && args[0] == "status" {
+		fmt.Fprint(os.Stdout, execStatusOutput)
+		os.Exit(0)
+	} else if len(args) == 2 && args[0] == "status" {
+		if args[1] == "sshd" {
+			fmt.Fprint(os.Stdout, execStatusSshdOutput)
+			os.Exit(0)
+		} else if args[1] == "postfix" {
+			fmt.Fprint(os.Stdout, execStatusPostfixOutput)
+			os.Exit(0)
+		} else if args[1] == "dovecot" {
+			fmt.Fprint(os.Stdout, execStatusDovecotOutput)
+			os.Exit(0)
+		}
+	}
+	fmt.Fprint(os.Stdout, "invalid argument")
+	os.Exit(1)
+}