Merge branch 'master' into honor-systemd-sysctl-masking

* master: (619 commits)
  Add support for clear scroll to high level REST client (elastic#25038)
  Tiny correction in inner-hits.asciidoc (elastic#25066)
  Added release notes for 6.0.0-alpha2
  Expand index expressions against indices only when managing aliases (elastic#23997)
  Collapse inner hits rest test should not skip 5.x
  Settings: Fix secure settings by prefix (elastic#25064)
  add `exclude_keys` option to KeyValueProcessor (elastic#24876)
  Test: update missing body tests to run against versions >= 5.5.0
  Track EWMA[1] of task execution time in search threadpool executor
  Removes an invalid assert in resizing big arrays which does not always hold (resizing can result in a smaller size than the current size, while the assert attempted to verify the new size is always greater than the current).
  Fixed NPEs caused by requests without content. (elastic#23497)
  Plugins can register pre-configured char filters (elastic#25000)
  Build: Allow preserving shared dir (elastic#24962)
  Tests: Make secure settings available from settings builder for tests (elastic#25037)
  [TEST] Skip wildcard expansion test due to breaking change
  Test that gradle and Java version types match (elastic#24943)
  Include duplicate jar when jarhell check fails
  Change ScriptContexts to use needs instead of uses$. (elastic#25036)
  Change `has_child`, `has_parent` queries and `childen` aggregation to work with the new join field type and at the same time maintaining support for the `_parent` meta field type.
  Remove comma-separated feature parsing for GetIndicesAction
  ...

.github/ISSUE_TEMPLATE.md

@@ -1,40 +1,46 @@
 <!--
-GitHub is reserved for bug reports and feature requests. The best place
-to ask a general question is at the Elastic Discourse forums at
-https://discuss.elastic.co. If you are in fact posting a bug report or
-a feature request, please include one and only one of the below blocks
-in your new issue. Note that whether you're filing a bug report or a
-feature request, ensure that your submission is for an
-[OS that we support](https://www.elastic.co/support/matrix#show_os).
-Bug reports on an OS that we do not support or feature requests
-specific to an OS that we do not support will be closed.
--->
 
-<!--
-If you are filing a bug report, please remove the below feature
-request block and provide responses for all of the below items.
+** Please read the guidelines below. **
+
+Issues that do not follow these guidelines are likely to be closed.
+
+1.  GitHub is reserved for bug reports and feature requests. The best place to
+    ask a general question is at the Elastic [forums](https://discuss.elastic.co).
+    GitHub is not the place for general questions.
+
+2.  Is this bug report or feature request for a supported OS? If not, it
+    is likely to be closed.  See https://www.elastic.co/support/matrix#show_os
+
+3.  Please fill out EITHER the feature request block or the bug report block
+    below, and delete the other block.
+
 -->
 
+<!-- Feature request -->
+
+**Describe the feature**:
+
+<!-- Bug report -->
+
 **Elasticsearch version**:
 
 **Plugins installed**: []
 
-**JVM version**:
+**JVM version** (`java -version`):
 
-**OS version**:
+**OS version** (`uname -a` if on a Unix-like system):
 
 **Description of the problem including expected versus actual behavior**:
 
 **Steps to reproduce**:
+
+Please include a *minimal* but *complete* recreation of the problem, including
+(e.g.) index creation, mappings, settings, query etc.  The easier you make for
+us to reproduce it, the more likely that somebody will take the time to look at it.
+
  1.
  2.
  3.
 
 **Provide logs (if relevant)**:
 
-<!--
-If you are filing a feature request, please remove the above bug
-report block and provide responses for all of the below items.
--->
-
-**Describe the feature**:

CONTRIBUTING.md

@@ -101,7 +101,11 @@ IntelliJ users can automatically configure their IDE: `gradle idea`
 then `File->New Project From Existing Sources`. Point to the root of
 the source directory, select
 `Import project from external model->Gradle`, enable
-`Use auto-import`.
+`Use auto-import`. Additionally, in order to run tests directly from 
+IDEA 2017.1 and above it is required to disable IDEA run launcher, 
+which can be achieved by adding `-Didea.no.launcher=true` 
+[JVM option](https://intellij-support.jetbrains.com/hc/en-us/articles/206544869-Configuring-JVM-options-and-platform-properties) 
+
 
 The Elasticsearch codebase makes heavy use of Java `assert`s and the
 test runner requires that assertions be enabled within the JVM. This

TESTING.asciidoc

@@ -350,11 +350,11 @@ These are the linux flavors the Vagrantfile currently supports:
 * debian-8 aka jessie, the current debian stable distribution
 * centos-6
 * centos-7
-* fedora-24
+* fedora-25
 * oel-6 aka Oracle Enterprise Linux 6
 * oel-7 aka Oracle Enterprise Linux 7
 * sles-12
-* opensuse-13
+* opensuse-42 aka Leap
 
 We're missing the following from the support matrix because there aren't high
 quality boxes available in vagrant atlas:
@@ -426,29 +426,49 @@ sudo -E bats $BATS_TESTS/*.bats
 You can also use Gradle to prepare the test environment and then starts a single VM:
 
 -------------------------------------------------
-gradle vagrantFedora24#up
+gradle vagrantFedora25#up
 -------------------------------------------------
 
-Or any of vagrantCentos6#up, vagrantDebian8#up, vagrantFedora24#up, vagrantOel6#up,
-vagrantOel7#up, vagrantOpensuse13#up, vagrantSles12#up, vagrantUbuntu1404#up,
-vagrantUbuntu1604#up.
+Or any of vagrantCentos6#up, vagrantCentos7#up, vagrantDebian8#up,
+vagrantFedora25#up, vagrantOel6#up, vagrantOel7#up, vagrantOpensuse13#up,
+vagrantSles12#up, vagrantUbuntu1404#up, vagrantUbuntu1604#up.
 
 Once up, you can then connect to the VM using SSH from the elasticsearch directory:
 
 -------------------------------------------------
-vagrant ssh fedora-24
+vagrant ssh fedora-25
 -------------------------------------------------
 
 Or from another directory:
 
 -------------------------------------------------
-VAGRANT_CWD=/path/to/elasticsearch vagrant ssh fedora-24
+VAGRANT_CWD=/path/to/elasticsearch vagrant ssh fedora-25
 -------------------------------------------------
 
 Note: Starting vagrant VM outside of the elasticsearch folder requires to
 indicates the folder that contains the Vagrantfile using the VAGRANT_CWD
 environment variable.
 
+== Testing backwards compatibility
+
+Backwards compatibility tests exist to test upgrading from each supported version
+to the current version. To run all backcompat tests use:
+
+-------------------------------------------------
+gradle bwcTest
+-------------------------------------------------
+
+A specific version can be tested as well. For example, to test backcompat with
+version 5.3.2 run:
+
+-------------------------------------------------
+gradle v5.3.2#bwcTest
+-------------------------------------------------
+
+When running `gradle check`, some minimal backcompat checks are run. Which version
+is tested depends on the branch. On master, this will test against the current
+stable branch. On the stable branch, it will test against the latest release
+branch. Finally, on a release branch, it will test against the most recent release.
 
 == Coverage analysis
 

Vagrantfile

@@ -56,12 +56,12 @@ Vagrant.configure(2) do |config|
     config.vm.box = "elastic/oraclelinux-7-x86_64"
     rpm_common config
   end
-  config.vm.define "fedora-24" do |config|
-    config.vm.box = "elastic/fedora-24-x86_64"
+  config.vm.define "fedora-25" do |config|
+    config.vm.box = "elastic/fedora-25-x86_64"
     dnf_common config
   end
-  config.vm.define "opensuse-13" do |config|
-    config.vm.box = "elastic/opensuse-13-x86_64"
+  config.vm.define "opensuse-42" do |config|
+    config.vm.box = "elastic/opensuse-42-x86_64"
     opensuse_common config
   end
   config.vm.define "sles-12" do |config|
@@ -104,6 +104,12 @@ SOURCE_PROMPT
 source /etc/profile.d/elasticsearch_prompt.sh
 SOURCE_PROMPT
       SHELL
+      # Creates a file to mark the machine as created by vagrant. Tests check
+      # for this file and refuse to run if it is not present so that they can't
+      # be run unexpectedly.
+      config.vm.provision "markerfile", type: "shell", inline: <<-SHELL
+        touch /etc/is_vagrant_vm
+      SHELL
     end
     config.config_procs.push ['2', set_prompt]
   end
@@ -263,7 +269,7 @@ def provision(config,
       echo "==> Installing Gradle"
       curl -sS -o /tmp/gradle.zip -L https://services.gradle.org/distributions/gradle-3.3-bin.zip
       unzip /tmp/gradle.zip -d /opt
-      rm -rf /tmp/gradle.zip 
+      rm -rf /tmp/gradle.zip
       ln -s /opt/gradle-3.3/bin/gradle /usr/bin/gradle
       # make nfs mounted gradle home dir writeable
       chown vagrant:vagrant /home/vagrant/.gradle

benchmarks/src/main/java/org/elasticsearch/benchmark/routing/allocation/Allocators.java

@@ -36,8 +36,6 @@
 import org.elasticsearch.gateway.GatewayAllocator;
 
 import java.lang.reflect.InvocationTargetException;
-import java.net.InetAddress;
-import java.net.UnknownHostException;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -49,7 +47,7 @@ private static class NoopGatewayAllocator extends GatewayAllocator {
         public static final NoopGatewayAllocator INSTANCE = new NoopGatewayAllocator();
 
         protected NoopGatewayAllocator() {
-            super(Settings.EMPTY, null, null);
+            super(Settings.EMPTY);
         }
 
         @Override

build.gradle

@@ -24,6 +24,7 @@ import org.eclipse.jgit.lib.RepositoryBuilder
 import org.gradle.plugins.ide.eclipse.model.SourceFolder
 import org.apache.tools.ant.taskdefs.condition.Os
 import org.elasticsearch.gradle.VersionProperties
+import org.elasticsearch.gradle.Version
 
 // common maven publishing configuration
 subprojects {
@@ -61,15 +62,52 @@ configure(subprojects.findAll { it.projectDir.toPath().startsWith(rootPath) }) {
   }
 }
 
-int prevMajor = Integer.parseInt(VersionProperties.elasticsearch.split('\\.')[0]) - 1
-String prevSnapshot = VersionProperties.elasticsearch.contains('alpha') ? '-SNAPSHOT' : ''
+/* Introspect all versions of ES that may be tested agains for backwards
+ * compatibility. It is *super* important that this logic is the same as the
+ * logic in VersionUtils.java, modulo alphas, betas, and rcs which are ignored
+ * in gradle because they don't have any backwards compatibility guarantees
+ * but are not ignored in VersionUtils.java because the tests expect them not
+ * to be. */
+Version currentVersion = Version.fromString(VersionProperties.elasticsearch.minus('-SNAPSHOT'))
+int prevMajor = currentVersion.major - 1
 File versionFile = file('core/src/main/java/org/elasticsearch/Version.java')
 List<String> versionLines = versionFile.readLines('UTF-8')
-int prevMinor = 0
+List<Version> versions = []
+// keep track of the previous major version's last minor, so we know where wire compat begins
+int prevMinorIndex = -1 // index in the versions list of the last minor from the prev major
+int lastPrevMinor = -1 // the minor version number from the prev major we most recently seen
 for (String line : versionLines) {
-  Matcher match = line =~ /\W+public static final Version V_${prevMajor}_(\d+)_.*/
+  /* Note that this skips alphas and betas which is fine because they aren't
+   * compatible with anything. */
+  Matcher match = line =~ /\W+public static final Version V_(\d+)_(\d+)_(\d+) .*/
   if (match.matches()) {
-    prevMinor = Math.max(Integer.parseInt(match.group(1)), prevMinor)
+    int major = Integer.parseInt(match.group(1))
+    int minor = Integer.parseInt(match.group(2))
+    int bugfix = Integer.parseInt(match.group(3))
+    Version foundVersion = new Version(major, minor, bugfix, false)
+    if (currentVersion != foundVersion) {
+      versions.add(foundVersion)
+    }
+    if (major == prevMajor && minor > lastPrevMinor) {
+      prevMinorIndex = versions.size() - 1
+      lastPrevMinor = minor
+    }
+  }
+}
+if (versions.toSorted { it.id } != versions) {
+  println "Versions: ${versions}"
+  throw new GradleException("Versions.java contains out of order version constants")
+}
+if (currentVersion.bugfix == 0) {
+  // If on a release branch, after the initial release of that branch, the bugfix version will
+  // be bumped, and will be != 0. On master and N.x branches, we want to test against the
+  // unreleased version of closest branch. So for those cases, the version includes -SNAPSHOT,
+  // and the bwc distribution will checkout and build that version.
+  Version last = versions[-1]
+  versions[-1] = new Version(last.major, last.minor, last.bugfix, true)
+  if (last.bugfix == 0) {
+    versions[-2] = new Version(
+        versions[-2].major, versions[-2].minor, versions[-2].bugfix, true)
   }
 }
 
@@ -80,10 +118,46 @@ allprojects {
     isEclipse = System.getProperty("eclipse.launcher") != null || gradle.startParameter.taskNames.contains('eclipse') || gradle.startParameter.taskNames.contains('cleanEclipse')
     isIdea = System.getProperty("idea.active") != null || gradle.startParameter.taskNames.contains('idea') || gradle.startParameter.taskNames.contains('cleanIdea')
     // for backcompat testing
-    bwcVersion = "${prevMajor}.${prevMinor}.0${prevSnapshot}"
+    indexCompatVersions = versions
+    wireCompatVersions = versions.subList(prevMinorIndex, versions.size())
+  }
+}
+
+task verifyVersions {
+  doLast {
+    if (gradle.startParameter.isOffline()) {
+      throw new GradleException("Must run in online mode to verify versions")
+    }
+    // Read the list from maven central
+    Node xml
+    new URL('https://repo1.maven.org/maven2/org/elasticsearch/elasticsearch/maven-metadata.xml').openStream().withStream { s ->
+        xml = new XmlParser().parse(s)
+    }
+    Set<Version> knownVersions = new TreeSet<>(xml.versioning.versions.version.collect { it.text() }.findAll { it ==~ /\d\.\d\.\d/ }.collect { Version.fromString(it) })
+
+    // Limit the known versions to those that should be index compatible, and are not future versions
+    knownVersions = knownVersions.findAll { it.major >= prevMajor && it.before(VersionProperties.elasticsearch) }
+
+    /* Limit the listed versions to those that have been marked as released.
+     * Versions not marked as released don't get the same testing and we want
+     * to make sure that we flip all unreleased versions to released as soon
+     * as possible after release. */
+    Set<Version> actualVersions = new TreeSet<>(indexCompatVersions.findAll { false == it.snapshot })
+
+    // Finally, compare!
+    if (knownVersions.equals(actualVersions) == false) {
+      throw new GradleException("out-of-date released versions\nActual  :" + actualVersions + "\nExpected:" + knownVersions +
+        "\nUpdate Version.java. Note that Version.CURRENT doesn't count because it is not released.")
+    }
   }
 }
 
+task branchConsistency {
+  description 'Ensures this branch is internally consistent. For example, that versions constants match released versions.'
+  group 'Verification'
+  dependsOn verifyVersions
+}
+
 subprojects {
   project.afterEvaluate {
     // include license and notice in jars
@@ -128,7 +202,6 @@ subprojects {
     "org.elasticsearch.client:transport:${version}": ':client:transport',
     "org.elasticsearch.test:framework:${version}": ':test:framework',
     "org.elasticsearch.distribution.integ-test-zip:elasticsearch:${version}": ':distribution:integ-test-zip',
-    "org.elasticsearch.distribution.zip:elasticsearch:${bwcVersion}": ':distribution:bwc-zip',
     "org.elasticsearch.distribution.zip:elasticsearch:${version}": ':distribution:zip',
     "org.elasticsearch.distribution.tar:elasticsearch:${version}": ':distribution:tar',
     "org.elasticsearch.distribution.rpm:elasticsearch:${version}": ':distribution:rpm',
@@ -138,8 +211,27 @@ subprojects {
     "org.elasticsearch.plugin:transport-netty4-client:${version}": ':modules:transport-netty4',
     "org.elasticsearch.plugin:reindex-client:${version}": ':modules:reindex',
     "org.elasticsearch.plugin:lang-mustache-client:${version}": ':modules:lang-mustache',
+    "org.elasticsearch.plugin:parent-join-client:${version}": ':modules:parent-join',
+    "org.elasticsearch.plugin:aggs-matrix-stats-client:${version}": ':modules:aggs-matrix-stats',
     "org.elasticsearch.plugin:percolator-client:${version}": ':modules:percolator',
   ]
+  if (indexCompatVersions[-1].snapshot) {
+    /* The last and second to last versions can be snapshots. Rather than use
+     * snapshots built by CI we connect these versions to projects that build
+     * those those versions from the HEAD of the appropriate branch. */
+    if (indexCompatVersions[-1].bugfix == 0) {
+      ext.projectSubstitutions["org.elasticsearch.distribution.deb:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-stable-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.rpm:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-stable-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.zip:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-stable-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.deb:elasticsearch:${indexCompatVersions[-2]}"] = ':distribution:bwc-release-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.rpm:elasticsearch:${indexCompatVersions[-2]}"] = ':distribution:bwc-release-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.zip:elasticsearch:${indexCompatVersions[-2]}"] = ':distribution:bwc-release-snapshot'
+    } else {
+      ext.projectSubstitutions["org.elasticsearch.distribution.deb:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-release-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.rpm:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-release-snapshot'
+      ext.projectSubstitutions["org.elasticsearch.distribution.zip:elasticsearch:${indexCompatVersions[-1]}"] = ':distribution:bwc-release-snapshot'
+    }
+  }
   project.afterEvaluate {
     configurations.all {
       resolutionStrategy.dependencySubstitution { DependencySubstitutions subs ->

buildSrc/build.gradle

@@ -156,4 +156,11 @@ if (project != rootProject) {
     testClass = 'org.elasticsearch.test.NamingConventionsCheckBadClasses$UnitTestCase'
     integTestClass = 'org.elasticsearch.test.NamingConventionsCheckBadClasses$IntegTestCase'
   }
+
+  task namingConventionsMain(type: org.elasticsearch.gradle.precommit.NamingConventionsTask) {
+    checkForTestsInMain = true
+    testClass = namingConventions.testClass
+    integTestClass = namingConventions.integTestClass
+  }
+  precommit.dependsOn namingConventionsMain
 }