diff --git a/build.gradle b/build.gradle
index 9bb08cf29dbbc..dc67294f3d140 100644
--- a/build.gradle
+++ b/build.gradle
@@ -575,3 +575,29 @@ gradle.projectsEvaluated {
     }
   }
 }
+
+apply plugin: 'compare-gradle-builds'
+
+if (System.properties.get("build.compare") != null) {
+  compareGradleBuilds {
+    ext.referenceProject = System.properties.get("build.compare")
+    doFirst {
+      if (file(referenceProject).exists() == false) {
+        throw new GradleException(
+                "Use git worktree to check out a version to compare against to ../elasticsearch_build_reference"
+        )
+      }
+    }
+    sourceBuild {
+      gradleVersion = "4.7" // does not default to gradle weapper of project dir, but current version
+      projectDir = referenceProject
+      tasks = ["clean", "assemble"]
+      arguments = ["-Dbuild.compare_friendly=true"]
+    }
+    targetBuild {
+      tasks = ["clean", "assemble"]
+      // use -Dorg.gradle.java.home= to alter jdk versions
+      arguments = ["-Dbuild.compare_friendly=true"]
+    }
+  }
+}
diff --git a/buildSrc/build.gradle b/buildSrc/build.gradle
index 5256968b6ca3e..9c139eee2152a 100644
--- a/buildSrc/build.gradle
+++ b/buildSrc/build.gradle
@@ -106,7 +106,6 @@ GradleVersion logVersion = GradleVersion.current() > GradleVersion.version('4.3'
 
 dependencies {
   compileOnly "org.gradle:gradle-logging:${logVersion.getVersion()}"
-  compile 'ru.vyarus:gradle-animalsniffer-plugin:1.2.0' // Gradle 2.14 requires a version > 1.0.1
 }
 
 /*****************************************************************************
diff --git a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
index eb3cd1dc8c6da..e69fc3821a768 100644
--- a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
+++ b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
@@ -348,7 +348,11 @@ class BuildPlugin implements Plugin<Project> {
                 // just a self contained test-fixture configuration, likely transitive and hellacious
                 return
             }
-            configuration.resolutionStrategy.failOnVersionConflict()
+            configuration.resolutionStrategy { 
+                failOnVersionConflict()
+                // work around https://github.com/gradle/gradle/issues/5692
+                preferProjectModules()
+            }
         })
 
         // force all dependencies added directly to compile/testCompile to be non-transitive, except for ES itself
@@ -475,13 +479,17 @@ class BuildPlugin implements Plugin<Project> {
                 }
             }
 
-            project.tasks.withType(GenerateMavenPom.class) { GenerateMavenPom t ->
-                // place the pom next to the jar it is for
-                t.destination = new File(project.buildDir, "distributions/${project.archivesBaseName}-${project.version}.pom")
-                // build poms with assemble (if the assemble task exists)
-                Task assemble = project.tasks.findByName('assemble')
-                if (assemble) {
-                    assemble.dependsOn(t)
+            // Work around Gradle 4.8 issue until we `enableFeaturePreview('STABLE_PUBLISHING')`
+            // https://github.com/gradle/gradle/issues/5696#issuecomment-396965185
+            project.getGradle().getTaskGraph().whenReady {
+                project.tasks.withType(GenerateMavenPom.class) { GenerateMavenPom t ->
+                    // place the pom next to the jar it is for
+                    t.destination = new File(project.buildDir, "distributions/${project.archivesBaseName}-${project.version}.pom")
+                    // build poms with assemble (if the assemble task exists)
+                    Task assemble = project.tasks.findByName('assemble')
+                    if (assemble) {
+                        assemble.dependsOn(t)
+                    }
                 }
             }
         }
@@ -625,6 +633,10 @@ class BuildPlugin implements Plugin<Project> {
                         jarTask.manifest.attributes('Change': shortHash)
                     }
                 }
+                // Force manifest entries that change by nature to a constant to be able to compare builds more effectively
+                if (System.properties.getProperty("build.compare_friendly", "false") == "true") {
+                    jarTask.manifest.getAttributes().clear()
+                }
             }
             // add license/notice files
             project.afterEvaluate {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index a5fe1cb94b9ee..f5a7e5e1fcf56 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 7962563f742fe..dc0be816f0f97 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.7-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.8-all.zip
 zipStoreBase=GRADLE_USER_HOME
-distributionSha256Sum=203f4537da8b8075e38c036a6d14cb71b1149de5bf0a8f6db32ac2833a1d1294
+zipStorePath=wrapper/dists
+distributionSha256Sum=da9600da2a28a43f5f77364deecbb9b01c1ddb7d3ecafe1d5c93bcd8a8059ab1
diff --git a/server/src/main/java/org/elasticsearch/bootstrap/Security.java b/server/src/main/java/org/elasticsearch/bootstrap/Security.java
index 734b15d509877..ca2a0ca3ed810 100644
--- a/server/src/main/java/org/elasticsearch/bootstrap/Security.java
+++ b/server/src/main/java/org/elasticsearch/bootstrap/Security.java
@@ -221,14 +221,16 @@ static Policy readPolicy(URL policyFile, Map<String, URL> codebases) {
                     if (aliasProperty.equals(property) == false) {
                         propertiesSet.add(aliasProperty);
                         String previous = System.setProperty(aliasProperty, url.toString());
-                        if (previous != null) {
+                        // allow to re-set to what was previously there. https://github.com/elastic/elasticsearch/issues/31324
+                        if (previous != null && url.toString().equals(previous) == false) {
                             throw new IllegalStateException("codebase property already set: " + aliasProperty + " -> " + previous +
                                                             ", cannot set to " + url.toString());
                         }
                     }
                     propertiesSet.add(property);
                     String previous = System.setProperty(property, url.toString());
-                    if (previous != null) {
+                    // allow to re-set to what was previously there. https://github.com/elastic/elasticsearch/issues/31324
+                    if (previous != null && url.toString().equals(previous) == false) {
                         throw new IllegalStateException("codebase property already set: " + property + " -> " + previous +
                                                         ", cannot set to " + url.toString());
                     }