Allow to override plugin variables

Closes #398

docs/command_line_reference.rst

@@ -167,6 +167,16 @@ Example::
 
 In this example, Rally will install the ``analysis-icu`` plugin and the ``x-pack`` plugin with the ``security`` configuration. See the reference documentation about :doc:`Elasticsearch plugins </elasticsearch_plugins>` for more details.
 
+``plugin-params``
+~~~~~~~~~~~~~~~~~
+
+Allows to override variables of Elasticsearch plugins.
+
+Example::
+
+    esrally --distribution-version=6.1.1. --elasticsearch-plugins="x-pack:monitoring-http" --plugin-params="monitoring_type:'https',monitoring_host:'some_remote_host',monitoring_port:10200,monitoring_user:'rally',monitoring_password:'m0n1t0r1ng'"
+
+This enables the HTTP exporter of `X-Pack Monitoring <https://www.elastic.co/products/x-pack/monitoring>`_ and exports the data to the configured monitoring host.
 
 ``pipeline``
 ~~~~~~~~~~~~

docs/elasticsearch_plugins.rst

@@ -39,6 +39,7 @@ To see which plugins are available, run ``esrally list elasticsearch-plugins``::
     repository-s3
     store-smb
     x-pack                   monitoring-local
+    x-pack                   monitoring-http
     x-pack                   security
 
 Rally supports plugins only for Elasticsearch 5.0 or better. As the availability of plugins may change from release to release we recommend that you include the ``--distribution-version`` parameter when listing plugins. By default Rally assumes that you want to benchmark the latest master version of Elasticsearch.
@@ -72,6 +73,12 @@ As mentioned above, Rally also allows you to specify a plugin configuration and
 .. note::
     To benchmark the ``security`` configuration of ``x-pack`` you need to add the following command line options: ``--client-options="use_ssl:true,verify_certs:false,basic_auth_user:'rally',basic_auth_password:'rally-password'" --cluster-health=yellow``
 
+You can also override plugin variables with ``--plugin-params`` which is needed for example if you want to use the ``monitoring-http`` configuration in order to export monitoring data. You can export monitoring data e.g. with the following configuration::
+
+    --elasticsearch-plugins="x-pack:monitoring-http" --plugin-params="monitoring_type:'https',monitoring_host:'some_remote_host',monitoring_port:10200,monitoring_user:'rally',monitoring_password:'m0n1t0r1ng'"
+
+The ``monitoring_user`` and ``monitoring_password`` parameters are optional, the other parameters are mandatory. For more details on the configuration options, please see the `Monitoring plugin documentation <https://www.elastic.co/guide/en/x-pack/current/monitoring-production.html>`_.
+
 If you are behind a proxy, please set the environment variable ``ES_JAVA_OPTS`` accordingly on each target machine as described in the `Elasticsearch plugin documentation <https://www.elastic.co/guide/en/elasticsearch/plugins/current/_other_command_line_parameters.html#_proxy_settings>`_.
 
 Building plugins from sources
@@ -217,6 +224,7 @@ Rally will now know about ``myplugin`` and its two configurations. Let's check t
     repository-s3
     store-smb
     x-pack                   monitoring-local
+    x-pack                   monitoring-http
     x-pack                   security
 
 As ``myplugin`` is not a core plugin, the Elasticsearch plugin manager does not know from where to install it, so we need to add the download URL to ``~/.rally/rally.ini`` as before::

esrally/mechanic/mechanic.py

@@ -505,7 +505,7 @@ def create(cfg, metrics_store, all_node_ips, cluster_settings=None, sources=Fals
     else:
         repo = team.team_repo(cfg)
         car = team.load_car(repo, cfg.opts("mechanic", "car.names"))
-        plugins = team.load_plugins(repo, cfg.opts("mechanic", "car.plugins"))
+        plugins = team.load_plugins(repo, cfg.opts("mechanic", "car.plugins"), cfg.opts("mechanic", "plugin.params"))
 
     if sources or distribution:
         s = supplier.create(cfg, sources, distribution, build, challenge_root_path, plugins)

esrally/mechanic/team.py

@@ -58,15 +58,15 @@ def list_plugins(cfg):
         console.println("No Elasticsearch plugins are available.\n")
 
 
-def load_plugin(repo, name, config):
+def load_plugin(repo, name, config, plugin_params={}):
     if config is not None:
         logger.info("Loading plugin [%s] with configuration(s) [%s]." % (name, config))
     else:
         logger.info("Loading plugin [%s] with default configuration." % name)
-    return PluginLoader(repo).load_plugin(name, config)
+    return PluginLoader(repo).load_plugin(name, config, plugin_params)
 
 
-def load_plugins(repo, plugin_names):
+def load_plugins(repo, plugin_names, plugin_params={}):
     def name_and_config(p):
         plugin_spec = p.split(":")
         if len(plugin_spec) == 1:
@@ -79,7 +79,7 @@ def name_and_config(p):
     plugins = []
     for plugin in plugin_names:
         plugin_name, plugin_config = name_and_config(plugin)
-        plugins.append(load_plugin(repo, plugin_name, plugin_config))
+        plugins.append(load_plugin(repo, plugin_name, plugin_config, plugin_params))
     return plugins
 
 
@@ -251,7 +251,7 @@ def _plugin_name_to_file(self, plugin_name):
     def _core_plugin(self, name):
         return next((p for p in self._core_plugins() if p.name == name and p.config is None), None)
 
-    def load_plugin(self, name, config_names):
+    def load_plugin(self, name, config_names, plugin_params={}):
         root_path = self._plugin_root_path(name)
         if not config_names:
             # maybe we only have a config folder but nothing else (e.g. if there is only an install hook)
@@ -300,6 +300,8 @@ def load_plugin(self, name, config_names):
                 if "variables" in config.sections():
                     for k, v in config["variables"].items():
                         variables[k] = v
+                # add all plugin params here to override any defaults
+                variables.update(plugin_params)
 
             # maybe one of the configs is really just for providing variables. However, we still require one config base overall.
             if len(config_paths) == 0:

esrally/rally.py

@@ -277,6 +277,11 @@ def positive_number(v):
             "--elasticsearch-plugins",
             help="define the Elasticsearch plugins to install. (default: install no plugins).",
             default="")
+        p.add_argument(
+            "--plugin-params",
+            help="define a comma-separate list of key:value pairs that are injected verbatim to all plugins as variables",
+            default=""
+        )
         p.add_argument(
             "--target-hosts",
             help="define a comma-separated list of host:port pairs which should be targeted iff using the pipeline 'benchmark-only' "
@@ -649,6 +654,7 @@ def main():
     cfg.add(config.Scope.applicationOverride, "mechanic", "repository.name", args.team_repository)
     cfg.add(config.Scope.applicationOverride, "mechanic", "car.names", csv_to_list(args.car))
     cfg.add(config.Scope.applicationOverride, "mechanic", "car.plugins", csv_to_list(args.elasticsearch_plugins))
+    cfg.add(config.Scope.applicationOverride, "mechanic", "plugin.params", kv_to_map(csv_to_list(args.plugin_params)))
     cfg.add(config.Scope.applicationOverride, "mechanic", "node.datapaths", csv_to_list(args.data_paths))
     if args.keep_cluster_running:
         cfg.add(config.Scope.applicationOverride, "mechanic", "keep.running", True)