devenv: add elasticsearch v6 filebeat integration (#16493)

Adds filebeat (log collector) to elasticsearch v6 docker block that 
collects Grafana logs.
Also adds a new elasticsearch v6 datasource and test dashboard 
thru provisioning.

devenv/docker/blocks/elastic6/docker-compose.yaml

@@ -13,3 +13,11 @@
     environment:
       FD_DATASOURCE: elasticsearch6
       FD_PORT: 11200
+
+  filebeat6:
+    image: docker.elastic.co/beats/filebeat:6.2.4
+    command: filebeat -e -strict.perms=false
+    volumes:
+      - ./docker/blocks/elastic6/filebeat.yml:/usr/share/filebeat/filebeat.yml:ro
+      - /var/log:/var/log:ro
+      - ../data/log:/var/log/grafana:ro

devenv/docker/blocks/elastic6/filebeat.yml

@@ -0,0 +1,183 @@
+###################### Filebeat Configuration Example #########################
+
+# This file is an example configuration file highlighting only the most common
+# options. The filebeat.reference.yml file from the same directory contains all the
+# supported options with more comments. You can use it as a reference.
+#
+# You can find the full configuration reference here:
+# https://www.elastic.co/guide/en/beats/filebeat/index.html
+
+# For more available modules and options, please see the filebeat.reference.yml sample
+# configuration file.
+
+#=========================== Filebeat prospectors =============================
+
+filebeat.prospectors:
+
+# Each - is a prospector. Most options can be set at the prospector level, so
+# you can use different prospectors for various configurations.
+# Below are the prospector specific configurations.
+
+- type: log
+  enabled: false
+  paths:
+    - /var/log/*.log
+- type: log
+  enabled: true
+  paths:
+    - /var/log/grafana/grafana.log
+  include_lines: ['lvl=info']
+  fields:
+    app: grafana
+    level: info
+- type: log
+  enabled: true
+  paths:
+    - /var/log/grafana/grafana.log
+  include_lines: ['lvl=eror']
+  fields:
+    app: grafana
+    level: error
+- type: log
+  enabled: true
+  paths:
+    - /var/log/grafana/grafana.log
+  include_lines: ['lvl=warn']
+  fields:
+    app: grafana
+    level: warning
+- type: log
+  enabled: true
+  paths:
+    - /var/log/grafana/grafana.log
+  include_lines: ['lvl=dbug']
+  fields:
+    app: grafana
+    level: debug
+
+#============================= Filebeat modules ===============================
+
+filebeat.config.modules:
+  # Glob pattern for configuration loading
+  path: ${path.config}/modules.d/*.yml
+
+  # Set to true to enable config reloading
+  reload.enabled: false
+
+  # Period on which files under path should be checked for changes
+  #reload.period: 10s
+
+#==================== Elasticsearch template setting ==========================
+
+setup.template.settings:
+  index.number_of_shards: 3
+  #index.codec: best_compression
+  #_source.enabled: false
+
+#================================ General =====================================
+
+# The name of the shipper that publishes the network data. It can be used to group
+# all the transactions sent by a single shipper in the web interface.
+#name:
+
+# The tags of the shipper are included in their own field with each
+# transaction published.
+#tags: ["service-X", "web-tier"]
+
+# Optional fields that you can specify to add additional information to the
+# output.
+#fields:
+#  env: staging
+
+
+#============================== Dashboards =====================================
+# These settings control loading the sample dashboards to the Kibana index. Loading
+# the dashboards is disabled by default and can be enabled either by setting the
+# options here, or by using the `-setup` CLI flag or the `setup` command.
+#setup.dashboards.enabled: false
+
+# The URL from where to download the dashboards archive. By default this URL
+# has a value which is computed based on the Beat name and version. For released
+# versions, this URL points to the dashboard archive on the artifacts.elastic.co
+# website.
+#setup.dashboards.url:
+
+#============================== Kibana =====================================
+
+# Starting with Beats version 6.0.0, the dashboards are loaded via the Kibana API.
+# This requires a Kibana endpoint configuration.
+setup.kibana:
+
+  # Kibana Host
+  # Scheme and port can be left out and will be set to the default (http and 5601)
+  # In case you specify and additional path, the scheme is required: http://localhost:5601/path
+  # IPv6 addresses should always be defined as: https://[2001:db8::1]:5601
+  #host: "localhost:5601"
+
+#============================= Elastic Cloud ==================================
+
+# These settings simplify using filebeat with the Elastic Cloud (https://cloud.elastic.co/).
+
+# The cloud.id setting overwrites the `output.elasticsearch.hosts` and
+# `setup.kibana.host` options.
+# You can find the `cloud.id` in the Elastic Cloud web UI.
+#cloud.id:
+
+# The cloud.auth setting overwrites the `output.elasticsearch.username` and
+# `output.elasticsearch.password` settings. The format is `<user>:<pass>`.
+#cloud.auth:
+
+#================================ Outputs =====================================
+
+# Configure what output to use when sending the data collected by the beat.
+
+#-------------------------- Elasticsearch output ------------------------------
+output.elasticsearch:
+  # Array of hosts to connect to.
+  hosts: ["elasticsearch6:9200"]
+
+  # Optional protocol and basic auth credentials.
+  #protocol: "https"
+  #username: "elastic"
+  #password: "changeme"
+
+#----------------------------- Logstash output --------------------------------
+#output.logstash:
+  # The Logstash hosts
+  #hosts: ["localhost:5044"]
+
+  # Optional SSL. By default is off.
+  # List of root certificates for HTTPS server verifications
+  #ssl.certificate_authorities: ["/etc/pki/root/ca.pem"]
+
+  # Certificate for SSL client authentication
+  #ssl.certificate: "/etc/pki/client/cert.pem"
+
+  # Client Certificate Key
+  #ssl.key: "/etc/pki/client/cert.key"
+
+#================================ Logging =====================================
+
+# Sets log level. The default log level is info.
+# Available log levels are: error, warning, info, debug
+#logging.level: debug
+
+# At debug level, you can selectively enable logging only for some components.
+# To enable all selectors use ["*"]. Examples of other selectors are "beat",
+# "publish", "service".
+#logging.selectors: ["*"]
+
+#============================== Xpack Monitoring ===============================
+# filebeat can export internal metrics to a central Elasticsearch monitoring
+# cluster.  This requires xpack monitoring to be enabled in Elasticsearch.  The
+# reporting is disabled by default.
+
+# Set to true to enable the monitoring reporter.
+#xpack.monitoring.enabled: false
+
+# Uncomment to send the metrics to Elasticsearch. Most settings from the
+# Elasticsearch output are accepted here as well. Any setting that is not set is
+# automatically inherited from the Elasticsearch output configuration, so if you
+# have the Elasticsearch output configured, you can simply uncomment the
+# following line.
+#xpack.monitoring.elasticsearch: