Heartbeat monitor code generator (elastic#5792)

- add support for `make create-monitor`
- code that needs to be adapted by user is marked with `IMPLEMENT_ME`

heartbeat/Makefile

@@ -28,3 +28,8 @@ fields:
 imports: python-env
 	@mkdir -p include
 	@${PYTHON_ENV}/bin/python ${ES_BEATS}/script/generate_imports.py --out monitors/defaults/default.go ${BEAT_PATH}
+
+# Create a new monitor. Requires the parameter MONITOR
+.PHONY: create-monitor
+create-monitor:
+	go run scripts/generate_monitor/main.go -monitor=${MONITOR}

heartbeat/scripts/generate_monitor/main.go

@@ -0,0 +1,184 @@
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"text/template"
+)
+
+func main() {
+	var (
+		monitor       string
+		generatorHome string
+		path          string
+	)
+	flag.StringVar(&monitor, "monitor", "", "Monitor name")
+	flag.StringVar(&generatorHome, "home", "./scripts/generator/{{monitor}}", "Generator home path")
+	flag.StringVar(&path, "path", "./monitors/active", "monitor output directory")
+	flag.Parse()
+
+	if monitor == "" {
+		if err := prompt("Monitor name [example]: ", &monitor); err != nil {
+			fatal(err)
+		}
+
+		if monitor == "" {
+			monitor = "example"
+		}
+	}
+
+	env := map[string]interface{}{
+		// variables
+		"monitor": noDot(monitor),
+
+		// functions
+		"upper": strings.ToUpper,
+		"lower": strings.ToLower,
+		"title": strings.Title,
+	}
+	if err := generate(generatorHome, filepath.Join(path, monitor), env); err != nil {
+		fatal(err)
+	}
+}
+
+func prompt(msg string, to interface{}) error {
+	fmt.Print(msg)
+	_, err := fmt.Scanln(to)
+	return err
+}
+
+// create a template function, such that the variable can be accessed without
+// the leading `.`.
+func noDot(v string) interface{} {
+	return func() string { return v }
+}
+
+func fatal(err error) {
+	fmt.Fprintln(os.Stderr, err)
+	os.Exit(1)
+}
+
+func generate(generatorPath string, outPath string, env map[string]interface{}) error {
+	root, err := filepath.Abs(generatorPath)
+	if err != nil {
+		return err
+	}
+
+	outPath, err = filepath.Abs(outPath)
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(outPath, os.ModeDir|os.ModePerm); err != nil {
+		return err
+	}
+
+	const tmplExt = ".tmpl"
+
+	return filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if path == root {
+			return nil
+		}
+
+		name, err := execNameTemplate(path[len(root)+1:], env)
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			dir := filepath.Join(outPath, name)
+			return os.MkdirAll(dir, os.ModeDir|os.ModePerm)
+		}
+
+		if filepath.Ext(name) != tmplExt {
+			return copyFile(filepath.Join(outPath, name), path)
+		}
+
+		// template file.
+		name = name[:len(name)-len(tmplExt)]
+		return copyTemplate(filepath.Join(outPath, name), path, env)
+	})
+}
+
+func execNameTemplate(in string, env map[string]interface{}) (string, error) {
+	var err error
+	tmpl := withFunc(template.New("name"), env)
+	tmpl, err = tmpl.Parse(in)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	err = tmpl.Execute(&buf, withEnv(env))
+	return buf.String(), err
+}
+
+func copyTemplate(to, tmplPath string, env map[string]interface{}) error {
+	var err error
+	tmpl := withFunc(template.New(filepath.Base(tmplPath)), env)
+	tmpl, err = tmpl.ParseFiles(tmplPath)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(to)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	tmpl = tmpl.Funcs(env)
+	return tmpl.Execute(out, env)
+}
+
+func copyFile(to, from string) error {
+	in, err := os.Open(from)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(to)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, in)
+	return err
+}
+
+func withFunc(tmpl *template.Template, env map[string]interface{}) *template.Template {
+	return tmpl.Funcs(filterEnv(func(v interface{}) bool {
+		return reflect.TypeOf(v).Kind() == reflect.Func
+	}, env))
+}
+
+func withEnv(env map[string]interface{}) map[string]interface{} {
+	return filterEnv(func(v interface{}) bool {
+		return reflect.TypeOf(v).Kind() != reflect.Func
+	}, env)
+}
+
+func filterEnv(pred func(interface{}) bool, env map[string]interface{}) map[string]interface{} {
+	tmp := map[string]interface{}{}
+	for k, v := range env {
+		if pred(v) {
+			tmp[k] = v
+		}
+	}
+
+	if len(tmp) == 0 {
+		return nil
+	}
+	return tmp
+}

heartbeat/scripts/generator/README.md

@@ -0,0 +1,33 @@
+## Readme
+
+Code generator for Heartbeat monitors.
+
+In order to add a new monitor type to Heartbeat, run `make create-monitor
+MONITOR=<name>` from the Heartbeat directory.
+
+```
+$ cd $GOPATH/src/github.com/elastic/beats/heartbeat
+$ make create-monitor MONITOR=<name>
+$ make update
+$ make # build heartbeat
+```
+
+`make update` is required to update the import list, such that the new monitor
+is compiled into Heartbeat.
+
+The new monitor will be added to the `monitors/active/<name>` sub directory.
+
+Monitor structure:
+- `config.go`: The monitor configuration options and configuration validation.
+- `check.go`: The monitor validation support.
+- `job.go`: Implements the ping function for connecting and validating an
+  endpoint. This file generates the monitor specific fields to an event.
+- `<name>.go`: The monitor entrypoint registering the factory for setting up
+  monitoring jobs.
+- `_meta/fields.yml`: Document the monitors event field.
+- `_meta/config.yml`: Minimal sample configuration file 
+- `_meta/config.reference.yml`: Reference configuration file. All availalbe
+  settings are documented in the reference file.
+
+Code comments tagged with `IMPLEMENT_ME` in the go and meta files give details
+on changes required to implement a new monitor type.

heartbeat/scripts/generator/{{monitor}}/_meta/config.reference.yml.tmpl

@@ -0,0 +1,62 @@
+- type: {{monitor}}
+
+  # Monitor name used for job name and document type
+  #name: {{monitor}}
+
+  # Enable/Disable monitor
+  #enabled: true
+
+  # Configure task schedule
+  schedule: '@every 30s'
+
+  # list of hosts to monitor
+  hosts: ["localhost"]
+
+  # list of ports to ping (used if host is given without portname)
+  ports: [12345]
+
+  # SOCKS5 proxy url
+  #proxy_url: ''
+
+  # Resolve hostnames locally instead on SOCKS5 server:
+  #proxy_use_local_resolver: false
+
+  # Configure file json file to be watched for changes to the monitor:
+  #watch.poll_file:
+    # Path to check for updates.
+    #path:
+
+    # Interval between file file changed checks.
+    #interval: 5s
+
+
+  # Configure IP protocol types to ping on if hostnames are configured.  Ping
+  # all resolvable IPs if `mode` is `all`, or only one IP if `mode` is `any`.
+  ipv4: true
+  ipv6: true
+  mode: any
+
+  # Configure file json file to be watched for changes to the monitor:
+  #watch.poll_file:
+    # Path to check for updates.
+    #path:
+
+    # Interval between file file changed checks.
+    #interval: 5s
+
+  # Total test connection and data exchange timeout
+  #timeout: 16s
+
+
+  # TLS/SSL connection settings:
+  #ssl:
+    # Certificate Authorities
+    #certificate_authorities: ['']
+
+    # Required TLS protocols
+    #supported_protocols: ["TLSv1.0", "TLSv1.1", "TLSv1.2"]
+
+  # IMPLEMENT_ME: document check/validation settings
+  #check:
+    #request:
+    #response:

heartbeat/scripts/generator/{{monitor}}/_meta/config.yml.tmpl

@@ -0,0 +1,9 @@
+- type: {{monitor}}
+  # list of hosts to monitor
+  hosts: ["localhost:12345"]
+
+  # Configure task schedule
+  schedule: '@every 30s'
+
+  # Total test connection and data exchange timeout
+  #timeout: 16s

heartbeat/scripts/generator/{{monitor}}/_meta/fields.yml.tmpl

@@ -0,0 +1,22 @@
+- key: {{monitor}}
+  title: "{{monitor|upper}} monitor"
+  description:
+  fields:
+    - name: {{monitor}}
+      type: group
+      description: >
+        {{monitor|upper}} related fields.
+      fields:
+        - name: rtt
+          type: group
+          description: >
+            {{monitor|upper}} layer round trip times.
+          fields:
+            - name: validate
+              type: group
+              description: >
+                Duration of validation step based on existing {{monitor|upper}} connection.
+              fields:
+                - name: us
+                  type: long
+                  description: Duration in microseconds

heartbeat/scripts/generator/{{monitor}}/check.go.tmpl

@@ -0,0 +1,15 @@
+package {{monitor}}
+
+import "net"
+
+// IMPLEMENT_ME: implement validator
+type validator struct {
+}
+
+func makeValidator(config *config) (*validator, error) {
+	return &validator{}, nil
+}
+
+func (v *validator) Check(conn net.Conn) error {
+	return nil
+}