Adds RPM rsync distributor

The RPM rsync distributor allows a user to publish an already published RPM repo
to a remote server.

closes #1759
https://pulp.plan.io/issues/1759

docs/tech-reference/index.rst

@@ -6,6 +6,7 @@ Technical Reference
 
    yum-plugins
    export-distributor
+   rsync-distributor
    iso-plugins
    rpm
    sort-index

docs/tech-reference/rsync-distributor.rst

@@ -1,92 +1,78 @@
-=================
-Rsync distributor
-=================
+=====================
+RPM rsync Distributor
+=====================
 
 Purpose:
 ========
-Rsync distributor should be used for syncing already published files into remote
-machine. That means, rsync distributor isn't designed to work as standalone
-distributor.
-
-How it works
-============
-Rsync distributor publishes in fast-forward mode by default. It selects
-new content since last_published timestamp, however it also check predistributor
-publish history if there weren't publishes that were non-fast-forward or
-failed. In that case, cdn_distributor publishes everything from scratch.
-Publish process is diveded into multiple steps:
-unit query, origin publish, content publish, extra data publish
-
-1. Unit query step fetchs units from database and creates realive symlinks to
-units _storage_dir in <working_repo_dir>/<extra_dir>/.relative
-
-2. origin publish syncs hard files from /var/lib/pulp/content/ to remote server
-There can by multiple origin publish steps if there are more then one content
-types to be synced.
-
-3. content publish syncs files <working_repo_dir>/<extra_dir>/.relative to
-remote server. Remote repo directory is calculated from ``remote_root`` and
-relative_url.
-
-4. extra data publish happens only if there are extra data to be synced. For
-example extra data for rpm repo are repodata/* files.
-
-
-Supported types
-==============
-For now, rsync distributor can sync any content from rpm and docker repositories
-
-Requirements
-============
-To work proprely, your repository needs to have associated distributor that
-procude data output. For docker repositories, docker_web_distributor is needed
-and for rpm repositories, yum_distributor is needed. For now, cdn_distributor
-will use configuration from first distributor with desired distributor_type
-mentioned above.
+The RPM rsync distributor publishes RPM content to a remote server. The distributor uses rsync over
+ssh to perform the file transfer.
 
 Configuration
 =============
-Here's example of cdn_distributor configuration
-
-{
-    "handler_type": "rsync",
-    "remote": {
-        "auth_type": "publickey",
-        "login": "rcm-cron",
-        "key_path": "/etc/httpd/id_rsa",
-        "ssh_login": "rcm-cron",
-        "host": "pulp04.web.stage.ext.phx2.redhat.com",
-        "remote_root": "/mnt/cdn/cdn-stage",
-        "skip_repodata": false
+Here's an example of rpm_rsync_distributor configuration:
+
+.. code-block:: json
+
+    {
+     "distributor_id": "my_rpm_rsync_distributor",
+     "distributor_type_id": "rpm_rsync_distributor",
+     "distributor_config": {
+        "remote": {
+            "auth_type": "publickey",
+            "ssh_user": "foo",
+            "ssh_identity_file": "/home/user/.ssh/id_rsa",
+            "host": "192.168.121.1",
+            "root": "/home/foo/pulp_root_dir"
+        },
+        "predistributor_id": "yum_distributor",
+        }
     }
-}
 
-``handler_type``
-  for now rsync is only supported handler
+
+``predistributor_id``
+  The id of the yum_distributor associated with the same repository. The publish history of this
+  yum_distributor determines if the publish will be incremental.
+
+The ``distributor_config`` contains a ``remote`` section made up of the following settings:
 
 ``auth_type``
-  for now publickey is only supported
+  Two authentication methods are supported: ``publickey`` and ``password``.
 
-``login``
-  ssh login to remote machine
+``ssh_user``
+  ssh user for remote server
 
-``key_path``
-  path to public key on pulp machine that will be used as identity file for ssh
+``ssh_identity_file``
+  A path to the private key that will be used as identity file for ssh. When ``auth_type`` is
+  ``publickey`` this is a required config. The key has to be readable by user ``apache``.
 
-``ssh_login``
-  artifact from old ages, can be probably removed. Isn't used anymore
+``ssh_password``
+  Password for ``ssh_user`` on remote server. Password is required when ``auth_type`` is 'password'.
 
 ``host``
-  remote hostname
+  The hostname of the remote server.
 
-``remote_root``
-  remote root directory with all the data. (content + published_contnet)
+``root``
+  Absolute path to the remote root directory where all the data (content and published content)
+  lives. Remote equivalent to ``/var/lib/pulp``. The repository's relative url is appended to the
+  ``root`` to determine the location of published repository.
 
 Optional configuration
 ----------------------
 
 ``skip_fast_forward``
-  if true, rsync distribtor will sync all content of repository.
+  If true, the rsync distributor will publish all of the content of the repository. If false
+  (default), the publish is incremental when the predistributor's last publish was incremental.
+
+``content_units_only``
+  If true, the distributor will publish content units only (e.g. ``/var/lib/pulp/content``). The
+  symlinks of a published repository will not be rsynced.
+
+``skip_repodata``
+  If true, repodata will be omitted from the publish.
+
+``delete``
+  If true, ``--delete`` is appended to the rsync command for symlinks and repodata so that any old files no longer present in
+  the local published directory are removed from the remote server.
 
-``origin_only``
-  if true, rsync distribtor will sync hard content (e.g. /var/lib/pulp/content)
+``remote_units_path``
+  The relative path from the ``root`` where unit files should live. Defaults to ``content/units``.

docs/user-guide/release-notes/2.10.x.rst

@@ -11,4 +11,8 @@ New Features
 * The yum distributor and export distributor now can use the configured checksum type for
   updateinfo.xml generation which may differ from the configured checksum type for all
   repo metadata. It can be specified via pulp-admin repo "create" and "update" commands.
+
 * Full re-sync can be done now using ``--force-full`` option.
+
+* The RPM rsync distributor has been added. The new distributor can be used to publish repositories
+  published by yum_distributor to a remote server.

plugins/pulp_rpm/plugins/db/models.py

@@ -880,6 +880,15 @@ def _update_location(package_element, filename):
         location_element = package_element.find('location')
         location_element.set('href', filename)
 
+    def get_symlink_name(self):
+        """
+        Provides the name that should be used when creating a symlink.
+
+        :return: file name as it appears in a published repository
+        :rtype: str
+        """
+        return self.filename
+
 
 class RPM(RpmBase):
     # TODO add docstring to this class