Beatless initial PR (#7837)

* Beatless initial PR

Add a new beat inside the x-pack folder under the Elastic License,
minimal requirement changes to have a build and a test running.

Main makefile exclude ASL2 for x-pack but check for Elastic.
Beats can override the license in their Makefile.

.travis.yml

@@ -99,6 +99,16 @@ jobs:
       go: $GO_VERSION
       stage: test
 
+    # Beatless
+    - os: linux
+      env: TARGETS="-C x-pack/beatless testsuite"
+      go: $GO_VERSION
+      stage: test
+    - os: osx
+      env: TARGETS="TEST_ENVIRONMENT=0 -C x-pack/beatless testsuite"
+      go: $GO_VERSION
+      stage: test
+
     # Generators
     - os: linux
       env: TARGETS="-C generator/metricbeat test"

x-pack/beatless/.gitignore

@@ -0,0 +1,9 @@
+.idea
+.vagrant
+.vscode
+/*/_meta/kibana.generated
+beatless
+build
+data
+fields.yml
+logs

x-pack/beatless/Makefile

@@ -0,0 +1,16 @@
+BEAT_NAME?=beatless
+LICENSE=Elastic
+BEAT_TITLE?=Beatless
+SYSTEM_TESTS?=true
+BEAT_PATH?=github.com/elastic/beats/x-pack/${BEAT_NAME}
+TEST_ENVIRONMENT?=false
+GOX_FLAGS=-arch="amd64 386 arm ppc64 ppc64le"
+ES_BEATS?=../../
+FIELDS_FILE_PATH=module
+
+# Path to the libbeat Makefile
+include $(ES_BEATS)/libbeat/scripts/Makefile
+
+# Runs all collection steps and updates afterwards
+.PHONY: collect
+collect:

x-pack/beatless/_meta/beat.yml

@@ -0,0 +1,5 @@
+################### Beatless Configuration Example #########################
+
+############################# Beatless ######################################
+
+beatless:

x-pack/beatless/_meta/fields.yml

@@ -0,0 +1,9 @@
+- key: beatless
+  title: beatless
+  description:
+  fields:
+    - name: counter
+      type: long
+      required: true
+      description: >
+        PLEASE UPDATE DOCUMENTATION

x-pack/beatless/beater/beatless.go

@@ -0,0 +1,72 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package beater
+
+import (
+	"fmt"
+
+	"github.com/elastic/beats/libbeat/beat"
+	"github.com/elastic/beats/libbeat/common"
+	"github.com/elastic/beats/libbeat/logp"
+
+	"github.com/elastic/beats/x-pack/beatless/bus"
+	"github.com/elastic/beats/x-pack/beatless/config"
+)
+
+// Beatless configuration.
+type Beatless struct {
+	done   chan struct{}
+	config config.Config
+	log    *logp.Logger
+
+	// TODO: Add registry reference here.
+}
+
+// New creates an instance of beatless.
+func New(b *beat.Beat, cfg *common.Config) (beat.Beater, error) {
+	c := config.DefaultConfig
+	if err := cfg.Unpack(&c); err != nil {
+		return nil, fmt.Errorf("error reading config file: %v", err)
+	}
+
+	bt := &Beatless{
+		done:   make(chan struct{}),
+		config: c,
+		log:    logp.NewLogger("beatless"),
+	}
+	return bt, nil
+}
+
+// Run starts beatless.
+func (bt *Beatless) Run(b *beat.Beat) error {
+	bt.log.Info("beatless is running")
+	defer bt.log.Info("beatless stopped running")
+
+	client, err := b.Publisher.Connect()
+	if err != nil {
+		return err
+	}
+	defer client.Close()
+
+	// NOTE: Do not review below, this is the minimal to have a working PR.
+	bus := bus.New(client)
+	// TODO: noop
+	bus.Listen()
+
+	// Stop until we are tell to shutdown.
+	// TODO this is where the events catcher starts.
+	select {
+	case <-bt.done:
+		// Stop catching events.
+	}
+	return nil
+}
+
+// Stop stops beatless.
+func (bt *Beatless) Stop() {
+	bt.log.Info("beatless is stopping")
+	defer bt.log.Info("beatless is stopped")
+	close(bt.done)
+}