Build: Build 5.x version of xpack for bwc tests to use (elastic/x-pack-elasticsearch#885)

This is analagous of the bwc-zip for elasticsearch. The one caveat is
due to the structure of how ES+xpack must be checked out, we end up with
a third clone of elasticsearch (the second being in :distribution:bwc-zip).
But the rolling upgrade integ test passes with this change.

relates elastic/x-pack-elasticsearch#870

Original commit: elastic/x-pack-elasticsearch@34bdce6e99

build.gradle

@@ -43,5 +43,8 @@ subprojects {
     approvedLicenses = ['Elasticsearch Confidential']
     additionalLicense 'ESCON', 'Elasticsearch Confidential', 'ELASTICSEARCH CONFIDENTIAL'
   }
-  ext.projectSubstitutions += [ "org.elasticsearch.plugin:x-pack-api:${version}": ':x-pack-elasticsearch:plugin' ]
+  ext.projectSubstitutions += [
+     "org.elasticsearch.plugin:x-pack-api:${version}": ':x-pack-elasticsearch:plugin',
+     "org.elasticsearch.plugin:x-pack:${bwcVersion}": ':x-pack-elasticsearch:plugin:bwc-zip'
+  ]
 }

plugin/bwc-zip/build.gradle

@@ -0,0 +1,116 @@
+import java.util.regex.Matcher
+import org.elasticsearch.gradle.LoggedExec
+
+/**
+ * This is a dummy project which does a local checkout of the previous
+ * major version's stable branch, and builds a snapshot. This allows backcompat
+ * tests in the next major version to test against the next unreleased minor
+ * version, without relying on snapshots.
+ */
+
+apply plugin: 'distribution'
+
+File esCheckoutDir = file("${buildDir}/bwc/checkout-es-5.x")
+File xpackCheckoutDir = file("${esCheckoutDir}-extra/x-pack-elasticsearch")
+task createElasticsearchClone(type: LoggedExec) {
+  onlyIf { esCheckoutDir.exists() == false }
+  commandLine = ['git', 'clone', rootDir, esCheckoutDir]
+}
+
+task createXPackClone(type: LoggedExec) {
+  onlyIf { xpackCheckoutDir.exists() == false }
+  commandLine = ['git', 'clone', project(':x-pack-elasticsearch').projectDir, xpackCheckoutDir]
+}
+
+// we use regular Exec here to ensure we always get output, regardless of logging level
+task findElasticsearchUpstream(type: Exec) {
+  dependsOn createElasticsearchClone
+  workingDir = esCheckoutDir
+  commandLine = ['git', 'remote', '-v']
+  ignoreExitValue = true
+  ByteArrayOutputStream output = new ByteArrayOutputStream()
+  standardOutput = output
+  doLast {
+    if (execResult.exitValue != 0) {
+      output.toString('UTF-8').eachLine { line -> logger.error(line) }
+      execResult.assertNormalExitValue()
+    }
+    project.ext.esUpstreamExists = false
+    output.toString('UTF-8').eachLine {
+      if (it.contains("upstream")) {
+        project.ext.esUpstreamExists = true
+      }
+    }
+  }
+}
+
+task findXPackUpstream(type: Exec) {
+  dependsOn createXPackClone
+  workingDir = xpackCheckoutDir
+  commandLine = ['git', 'remote', '-v']
+  ignoreExitValue = true
+  ByteArrayOutputStream output = new ByteArrayOutputStream()
+  standardOutput = output
+  doLast {
+    if (execResult.exitValue != 0) {
+      output.toString('UTF-8').eachLine { line -> logger.error(line) }
+      execResult.assertNormalExitValue()
+    }
+    project.ext.xpackUpstreamExists = false
+    output.toString('UTF-8').eachLine {
+      if (it.contains("upstream")) {
+        project.ext.xpackUpstreamExists = true
+      }
+    }
+  }
+}
+
+task addElasticsearchUpstream(type: LoggedExec) {
+  dependsOn findElasticsearchUpstream
+  onlyIf { project.ext.esUpstreamExists == false }
+  workingDir = esCheckoutDir
+  commandLine = ['git', 'remote', 'add', 'upstream', 'git@github.com:elastic/elasticsearch.git']
+}
+
+task addXPackUpstream(type: LoggedExec) {
+  dependsOn findXPackUpstream
+  onlyIf { project.ext.xpackUpstreamExists == false }
+  workingDir = xpackCheckoutDir
+  commandLine = ['git', 'remote', 'add', 'upstream', 'git@github.com:elastic/x-pack-elasticsearch.git']
+}
+
+task fetchElasticsearchLatest(type: LoggedExec) {
+  dependsOn addElasticsearchUpstream
+  workingDir = esCheckoutDir
+  commandLine = ['git', 'fetch', 'upstream']
+}
+
+task fetchXPackLatest(type: LoggedExec) {
+  dependsOn addXPackUpstream
+  workingDir = xpackCheckoutDir
+  commandLine = ['git', 'fetch', 'upstream']
+}
+
+task checkoutElasticsearchBwcBranch(type: LoggedExec) {
+  dependsOn fetchElasticsearchLatest
+  workingDir = esCheckoutDir
+  commandLine = ['git', 'checkout', 'upstream/5.x']
+}
+
+task checkoutXPackBwcBranch(type: LoggedExec) {
+  dependsOn fetchXPackLatest
+  workingDir = xpackCheckoutDir
+  commandLine = ['git', 'checkout', 'upstream/5.x']
+}
+
+File bwcZip = file("${xpackCheckoutDir}/plugin/build/distributions/x-pack-${bwcVersion}.zip")
+task buildBwcVersion(type: GradleBuild) {
+  dependsOn checkoutXPackBwcBranch, checkoutElasticsearchBwcBranch
+  dir = xpackCheckoutDir
+  tasks = [':x-pack-elasticsearch:plugin:assemble']
+}
+
+artifacts {
+  'default' file: bwcZip, name: 'x-pack', type: 'zip', builtBy: buildBwcVersion
+}
+

qa/rolling-upgrade/build.gradle

@@ -56,7 +56,7 @@ task oldClusterTest(type: RestIntegTestTask) {
 oldClusterTestCluster {
     plugin ':x-pack-elasticsearch:plugin'
     distribution = 'zip'
-    bwcVersion = '5.4.0-SNAPSHOT' // TODO: either randomize, or make this settable with sysprop
+    bwcVersion = project.bwcVersion // TODO: either randomize, or make this settable with sysprop
     numBwcNodes = 2
     numNodes = 2
     clusterName = 'rolling-upgrade'