Force runtime JDK in benchmarks

With this commit we enforce a runtime JDK in benchmarks. This is
necessary because Rally will choose the JDK at runtime based on the
allowed / installed JDK versions. By default we stick to JDK 8 (as is).

Relates elastic/rally#518
Relates elastic#68

night_rally.sh

@@ -37,6 +37,7 @@ MODE="nightly"
 RELEASE="master"
 # only needed for ad-hoc benchmarks
 REVISION="latest"
+RUNTIME_JDK="8"
 TARGET_HOST="localhost:9200"
 X_PACK=""
 TRACKS_FILE=""
@@ -71,6 +72,10 @@ case ${i} in
     REVISION="${i#*=}"
     shift # past argument=value
     ;;
+    --runtime-jdk=*)
+    RUNTIME_JDK="${i#*=}"
+    shift # past argument=value
+    ;;
     --release=*)
     RELEASE="${i#*=}"
     shift # past argument=value
@@ -186,6 +191,7 @@ es-night-rally \
     ${NIGHT_RALLY_DRY_RUN} \
     ${SKIP_ANSIBLE_PARAM} \
     --fixtures="${FIXTURES}" \
+    --runtime-jdk="${RUNTIME_JDK}" \
     --revision="${REVISION}" \
     --release="${RELEASE}" \
     --tracks="${TRACKS_FILE}" \

night_rally/night_rally.py

@@ -342,9 +342,10 @@ class StandardParams:
     """
     Extracts all parameters that are needed for all Rally invocations.
     """
-    def __init__(self, configuration_name, effective_start_date, user_tag):
+    def __init__(self, configuration_name, effective_start_date, runtime_jdk, user_tag):
         self.configuration_name = configuration_name
         self.effective_start_date = effective_start_date
+        self.runtime_jdk = runtime_jdk
         self.user_tag = user_tag
 
     def __call__(self, race_config):
@@ -358,6 +359,7 @@ def __call__(self, race_config):
             "car": [race_config.car],
             "user-tag": self.format_tag(additional_tags={"name": race_config.name})
         }
+        add_if_present(params, "runtime-jdk", self.runtime_jdk)
         add_if_present(params, "car-params", race_config.car_params)
         add_if_present(params, "track-params", race_config.track_params)
         add_if_present(params, "elasticsearch-plugins", race_config.plugins)
@@ -680,6 +682,10 @@ def parse_args():
         "--release",
         help="Specify release string to use for comparison reports",
         default="master")
+    parser.add_argument(
+        "--runtime-jdk",
+        help="The major version of the runtime JDK to use.",
+        default=None)
     parser.add_argument(
         "--tracks",
         help="Path to the tracks.json file that contains the tracks to run",
@@ -737,7 +743,7 @@ def main():
         params.append(TelemetryParams(args.telemetry, args.telemetry_params))
 
     if release_mode:
-        params.append(StandardParams(env_name, start_date, release_tag))
+        params.append(StandardParams(env_name, start_date, args.runtime_jdk, release_tag))
         if docker_benchmark:
             if x_pack:
                 raise RuntimeError("User specified x-pack configuration [%s] but this is not supported for Docker benchmarks." % x_pack)
@@ -749,11 +755,11 @@ def main():
             command = ReleaseCommand(params, x_pack, release)
     elif adhoc_mode:
         logger.info("Running adhoc benchmarks for revision [%s] against %s." % (args.revision, target_hosts))
-        params.append(StandardParams(env_name, start_date, release_tag))
+        params.append(StandardParams(env_name, start_date, args.runtime_jdk, release_tag))
         command = AdHocCommand(params, args.revision)
     else:
         logger.info("Running nightly benchmarks against %s." % target_hosts)
-        params.append(StandardParams(env_name, start_date, release_tag))
+        params.append(StandardParams(env_name, start_date, args.runtime_jdk, release_tag))
         command = NightlyCommand(params, start_date)
 
     rally_failure = run_rally(tracks, target_hosts, command, args.dry_run, args.skip_ansible)