GEODE-3556: Add support for setting the user inside docker containers

gradle.properties

@@ -53,6 +53,6 @@ nexusSignArchives = true
 # Control how many concurrent dunit (using docker) tests will be run
 dunitParallelForks = 8
 # This is the name of the Docker image for running parallel dunits
-dunitDockerImage = openjdk:8
+dunitDockerImage = apachegeode/geode-build
 # Docker user for parallel dunit tests
 dunitDockerUser = root

gradle/docker.gradle

@@ -53,10 +53,14 @@ def dockerConfig = {
     // Add volumes configured by top-level build script
     volumes << project.dunitDockerVolumes
 
+    // specify the user for starting Gradle test worker within the container.
+    user = dunitDockerUser
+
     beforeContainerCreate = { cmd, client ->
       def javaHomeIdx = -1
       def pathIdx = -1
-      def tmpEnv = cmd.getEnv()
+      def tmpEnv = []
+      cmd.getEnv().each { tmpEnv << it }
 
       tmpEnv.eachWithIndex { x, j ->
         if (x.startsWith('JAVA_HOME')) {
@@ -75,6 +79,16 @@ def dockerConfig = {
         tmpEnv[pathIdx] = 'PATH_REMOVED='
       }
 
+      // Unfortunately this snippet of code is here and is required by dev-tools/docker/base/entrypoint.sh.
+      // This allows preserving the outer user inside the running container. Required for Jenkins
+      // and other environments. There doesn't seem to be a way to pass this environment variable
+      // in from a Jenkins Gradle job.
+      if (System.env['LOCAL_USER_ID'] == null) {
+        def username = System.getProperty("user.name")
+        def uid = ['id', '-u', username].execute().text.trim()
+        tmpEnv << ("LOCAL_USER_ID=${uid}" as String)
+      }
+
       cmd.withEnv(tmpEnv)
 
       // Infer the index of this invocation