Don't load libs path if not using it (elastic#1540)

This PR fixes an issue where a dependency installed via the Track Dependencies mechanism lingers for esrally invocations where it is not needed or wanted. Also fixes elastic#1474

esrally/driver/driver.py

@@ -473,7 +473,7 @@ def receiveMsg_Bootstrap(self, msg, sender):
         # load node-specific config to have correct paths available
         self.cfg = load_local_config(msg.config)
         # this instance of load_track occurs once per host, so install dependencies if necessary
-        load_track(self.cfg, install_dependencies=True)
+        load_track(self.cfg, install_dependencies=False)
         self.send(sender, ReadyForWork())
 
     @actor.no_retry("track preparator")  # pylint: disable=no-value-for-parameter

esrally/racecontrol.py

@@ -191,7 +191,7 @@ def setup(self, sources=False):
             if specified_version < min_es_version:
                 raise exceptions.SystemSetupError(f"Cluster version must be at least [{min_es_version}] but was [{distribution_version}]")
 
-        self.current_track = track.load_track(self.cfg, install_dependencies=False)
+        self.current_track = track.load_track(self.cfg, install_dependencies=True)
         self.track_revision = self.cfg.opts("track", "repository.revision", mandatory=False)
         challenge_name = self.cfg.opts("track", "challenge.name")
         self.current_challenge = self.current_track.find_challenge_or_default(challenge_name)

esrally/rally.py

@@ -20,6 +20,7 @@
 import logging
 import os
 import platform
+import shutil
 import sys
 import time
 import uuid
@@ -1081,6 +1082,17 @@ def main():
             sys.exit(0)
         logger.info("Detected a working Internet connection.")
 
+    def _trap(function, path, exc_info):
+        if exc_info[0] == FileNotFoundError:
+            # couldn't delete because it was already clean
+            return
+        logging.exception("Failed to clean up [%s] with [%s]", path, function, exc_info=True)
+        raise exceptions.SystemSetupError(f"Unable to clean [{paths.libs()}]. See Rally log for more information.")
+
+    # fully destructive is fine, we only allow one Rally to run at a time and we will rely on the pip cache for download caching
+    logging.info("Cleaning track dependency directory [%s]...", paths.libs())
+    shutil.rmtree(paths.libs(), onerror=_trap)
+
     result = dispatch_sub_command(arg_parser, args, cfg)
 
     end = time.time()

esrally/track/loader.py

@@ -19,7 +19,6 @@
 import logging
 import os
 import re
-import shutil
 import subprocess
 import sys
 import tempfile
@@ -195,18 +194,7 @@ def load_track(cfg, install_dependencies=False):
 
 
 def _install_dependencies(dependencies):
-    def _cleanup():
-        # fully destructive is fine, we only allow one Rally to run at a time and we will rely on the pip cache for download caching
-        console.info("Cleaning track dependency directory...")
-        logging.info("Cleaning track dependency directory [%s]...", paths.libs())
-        shutil.rmtree(paths.libs(), onerror=_trap)
-
-    def _trap(function, path, exc_info):
-        logging.exception("Failed to clean up [%s] with [%s]", path, function, exc_info=True)
-        raise exceptions.SystemSetupError(f"Unable to clean [{paths.libs()}]. See Rally log for more information.")
-
     if dependencies:
-        _cleanup()
         log_path = os.path.join(paths.logs(), "dependency.log")
         console.info(f"Installing track dependencies [{', '.join(dependencies)}]")
         try:
@@ -249,7 +237,6 @@ def load_track_plugins(
     register_runner=None,
     register_scheduler=None,
     register_track_processor=None,
-    install_dependencies=False,
     force_update=False,
 ):
     """
@@ -260,7 +247,6 @@ def load_track_plugins(
     :param register_runner: An optional function where runners can be registered.
     :param register_scheduler: An optional function where custom schedulers can be registered.
     :param register_track_processor: An optional function where track processors can be registered.
-    :param install_dependencies: If set to ``True``, install declared dependencies from the track.py. Defaults to ``False``.
     :param force_update: If set to ``True`` this ensures that the track is first updated from the remote repository.
                          Defaults to ``False``.
     :return: True iff this track defines plugins and they have been loaded.