[DOC] simplify docs for repository-hdfs

docs/plugins/repository-hdfs.asciidoc

@@ -8,29 +8,25 @@ The HDFS repository plugin adds support for using HDFS File System as a reposito
 [float]
 ==== Installation
 
-This plugin can be installed using the plugin manager using _one_ of the following packages:
+This plugin can be installed through the plugin manager:
 
 [source,sh]
 ----------------------------------------------------------------
 sudo bin/plugin install repository-hdfs
-sudo bin/plugin install repository-hdfs-hadoop2
-sudo bin/plugin install repository-hdfs-lite
 ----------------------------------------------------------------
 
-The chosen plugin must be installed on every node in the cluster, and each node must
+The plugin must be installed on _every_ node in the cluster, and each node must
 be restarted after installation.
 
 [[repository-hdfs-remove]]
 [float]
 ==== Removal
 
-The plugin can be removed by specifying the _installed_ package using _one_ of the following commands:
+The plugin can be removed by specifying the _installed_ package:
 
 [source,sh]
 ----------------------------------------------------------------
 sudo bin/plugin remove repository-hdfs
-sudo bin/plugin remove repository-hdfs-hadoop2
-sudo bin/plugin remove repository-hdfs-lite
 ----------------------------------------------------------------
 
 The node must be stopped before removing the plugin.
@@ -38,49 +34,15 @@ The node must be stopped before removing the plugin.
 [[repository-hdfs-usage]]
 ==== Getting started with HDFS
 
-The HDFS snapshot/restore plugin comes in three _flavors_:
+The HDFS snapshot/restore plugin is built against the latest Apache Hadoop 2.x (currently 2.7.1). If the distro you are using is not protocol
+compatible with Apache Hadoop, consider replacing the Hadoop libraries inside the plugin folder with your own (you might have to adjust the security permissions required).
 
-* Default / Hadoop 1.x::
-The default version contains the plugin jar alongside Apache Hadoop 1.x (stable) dependencies.
-* YARN / Hadoop 2.x::
-The `hadoop2` version contains the plugin jar plus the Apache Hadoop 2.x (also known as YARN) dependencies.
-* Lite::
-The `lite` version contains just the plugin jar, without any Hadoop dependencies. The user should provide these (read below).
+Even if Hadoop is already installed on the Elasticsearch nodes, for security reasons, the required libraries need to be placed under the plugin folder.
+Note that in most cases, if the distro is compatible, one simply needs to configure the repository with the appropriate Hadoop configuration files (see below).
 
-[[repository-hdfs-flavor]]
-===== What version to use?
-
-It depends on whether Hadoop is locally installed or not and if not, whether it is compatible with Apache Hadoop clients.
-
-* Are you using Apache Hadoop (or a _compatible_ distro) and do not have installed on the Elasticsearch nodes?::
-+
-If the answer is yes, for Apache Hadoop 1 use the default `repository-hdfs` or `repository-hdfs-hadoop2` for Apache Hadoop 2.
-+
-* If you are have Hadoop installed locally on the Elasticsearch nodes or are using a certain distro::
-+
-Use the `lite` version and place your Hadoop _client_ jars and their dependencies in the plugin folder under `hadoop-libs`.
-For large deployments, it is recommended to package the libraries in the plugin zip and deploy it manually across nodes 
-(and thus avoiding having to do the libraries setup on each node).
-
-[[repository-hdfs-security]]
-==== Handling JVM Security and Permissions
-
-Out of the box, Elasticsearch runs in a JVM with the security manager turned _on_ to make sure that unsafe or sensitive actions
-are allowed only from trusted code. Hadoop however is not really designed to run under one; it does not rely on privileged blocks
-to execute sensitive code, of which it uses plenty.
-
-The `repository-hdfs` plugin provides the necessary permissions for both Apache Hadoop 1.x and 2.x (latest versions) to successfully
-run in a secured JVM as one can tell from the number of permissions required when installing the plugin.
-However using a certain Hadoop File-System (outside DFS), a certain distro or operating system (in particular Windows), might require 
-additional permissions which are not provided by the plugin.
-
-In this case there are several workarounds:
-* add the permission into `plugin-security.policy` (available in the plugin folder)
-
-* disable the security manager through `es.security.manager.enabled=false` configurations setting - NOT RECOMMENDED
-
-If you find yourself in such a situation, please let us know what Hadoop distro version and OS you are using and what permission is missing
-by raising an issue. Thank you!
+Windows Users::
+Using Apache Hadoop on Windows is problematic and thus it is not recommended. For those _really_ wanting to use it, make sure you place the elusive `winutils.exe` under the
+plugin folder and point `HADOOP_HOME` variable to it; this should minimize the amount of permissions Hadoop requires (though one would still have to add some more).
 
 [[repository-hdfs-config]]
 ==== Configuration Properties
@@ -104,15 +66,4 @@ repositories
 ----
 
 NOTE: Be careful when including a paths within the `uri` setting; Some implementations ignore them completely while
-others consider them. In general, we recommend keeping the `uri` to a minimum and using the `path` element instead.
-
-[[repository-hdfs-other-fs]]
-==== Plugging other file-systems
-
-Any HDFS-compatible file-systems (like Amazon `s3://` or Google `gs://`) can be used as long as the proper Hadoop
-configuration is passed to the Elasticsearch plugin. In practice, this means making sure the correct Hadoop configuration
-files (`core-site.xml` and `hdfs-site.xml`) and its jars are available in plugin classpath, just as you would with any
-other Hadoop client or job.
-
-Otherwise, the plugin will only read the _default_, vanilla configuration of Hadoop and will not be able to recognized
-the plugged-in file-system.
+others consider them. In general, we recommend keeping the `uri` to a minimum and using the `path` element instead.