[GPU-Plugin] Add basic continuous integration for GPU plugin. (#2431)

Jenkinsfile

@@ -0,0 +1,55 @@
+// -*- mode: groovy -*-
+// Jenkins pipeline
+// See documents at https://jenkins.io/doc/book/pipeline/jenkinsfile/
+
+// command to start a docker container
+docker_run = 'tests/ci_build/ci_build.sh'
+
+// timeout in minutes
+max_time = 60
+
+// initialize source codes
+def init_git() {
+  retry(5) {
+    try {
+      timeout(time: 2, unit: 'MINUTES') {
+        checkout scm
+        sh 'git submodule update --init'
+      }
+    } catch (exc) {
+      deleteDir()
+      error "Failed to fetch source codes"
+    }
+  }
+}
+
+stage('Build') {
+    node('GPU' && 'linux') {
+      ws('workspace/xgboost/build-gpu-cmake') {
+        init_git()
+  	timeout(time: max_time, unit: 'MINUTES') {
+      		sh "${docker_run} gpu tests/ci_build/build_gpu_cmake.sh"
+	}
+      }
+    }
+    node('GPU' && 'linux') {
+      ws('workspace/xgboost/build-gpu-make') {
+        init_git()
+  	timeout(time: max_time, unit: 'MINUTES') {
+      		sh "${docker_run} gpu make PLUGIN_UPDATER_GPU=ON"
+	}
+      }
+    }
+}
+
+
+stage('Unit Test') {
+    node('GPU' && 'linux') {
+      ws('workspace/xgboost/unit-test') {
+        init_git()
+  	timeout(time: max_time, unit: 'MINUTES') {
+      		sh "${docker_run} gpu tests/ci_build/test_gpu.ssh"
+	}
+      }
+    }
+}