Add script to cache dependencies

.ci/packer_cache.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+SCRIPT="$0"
+
+# SCRIPT might be an arbitrarily deep series of symbolic links; loop until we
+# have the concrete path
+while [ -h "$SCRIPT" ] ; do
+  ls=$(ls -ld "$SCRIPT")
+  # Drop everything prior to ->
+  link=$(expr "$ls" : '.*-> \(.*\)$')
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=$(dirname "$SCRIPT")/"$link"
+  fi
+done
+
+source $(dirname "${SCRIPT}")/java-versions.properties
+JAVA_HOME="${HOME}"/.java/${ES_BUILD_JAVA} ./gradlew resolveAllDependencies --parallel

build.gradle

@@ -628,3 +628,11 @@ if (System.properties.get("build.compare") != null) {
     }
   }
 }
+
+allprojects {
+  task resolveAllDependencies {
+    doLast {
+      configurations.findAll { it.isCanBeResolved() }.each { it.resolve() }
+    }
+  }
+}