Merge ~jingni.wjj/cloud-init:add_aliyun_doc into cloud-init:master

[Junjie.Wang]

doc: Add documentation for AliYun datasource.

Just add some documentation to readthedocs for AliYun.

[Scott Moser (smoser)]

Hi Junjie,

Thank you for the merge proposal.

I've done some changes and suggested them form merge into your branch at
 https://code.launchpad.net/~smoser/cloud-init/+git/cloud-init/+merge/343546

If you agree with those changes you can:

 git remote add smoser https://git.launchpad.net/~smoser/cloud-init
 git fetch smoser
 git merge --squash smoser/doc/add_aliyun_doc
 git push --force HEAD

Also, please fix your git config for name and email.
The 'name' field in your commit is set to jingni.wjj. I believe you have previously contributed with that set to 'Junjie Wang'.

Thanks.

review: Needs Fixing

Unmerged commits

4558c38... by Junjie.Wang on 2018-04-19

Squashed commit of the following:

commit 7df94002f20836f8d8849e7435d7e8e147aba620
Author: Scott Moser <email address hidden>
Date: Wed Apr 18 12:13:46 2018 -0400

    Suggested changes.

     - General re-wording and re-formatting.
     - Mention 'AliYun' specifically as that is the datasource name.
     - Add to topics/datasources.rst so it shows up in the list.
     - Make a single subsection 'Alibaba Cloud (AliYun)'.
     - Use subsubsections (^) for 'Versions', 'userdata' 'metadata'
     - use shell code blocks and 'curl' to show grabbing data.
     - converted dos to unix carriage returns
     - removed a non-breaking space (U+FEFF).

0f8a382... by Junjie.Wang on 2018-04-13

add doc describe aliyun datasource

diff --git a/doc/rtd/topics/datasources.rst b/doc/rtd/topics/datasources.rst
index 7e2854d..38ba75d 100644
--- a/doc/rtd/topics/datasources.rst
+++ b/doc/rtd/topics/datasources.rst
@@ -80,6 +80,7 @@ Follow for more information.
 .. toctree::
    :maxdepth: 2
 
+   datasources/aliyun.rst
    datasources/altcloud.rst
    datasources/azure.rst
    datasources/cloudsigma.rst
diff --git a/doc/rtd/topics/datasources/aliyun.rst b/doc/rtd/topics/datasources/aliyun.rst
new file mode 100644
index 0000000..3f4f40c
--- /dev/null
+++ b/doc/rtd/topics/datasources/aliyun.rst
@@ -0,0 +1,74 @@
+.. _datasource_aliyun:
+
+Alibaba Cloud (AliYun)
+======================
+The ``AliYun`` datasource reads data from Alibaba Cloud ECS.  Support is
+present in cloud-init since 0.7.9.
+
+Metadata Service
+----------------
+The Alibaba Cloud metadata service is available at the well known url
+``http://100.100.100.200/``. For more information see
+Alibaba Cloud ECS on `metadata
+<https://www.alibabacloud.com/help/zh/faq-detail/49122.htm>`__.
+
+Versions
+^^^^^^^^
+Like the EC2 metadata service, Alibaba Cloud's metadata service provides
+versioned data under specific paths.  As of April 2018, there are only
+``2016-01-01`` and ``latest`` versions.
+
+It is expected that the dated version will maintain a stable interface but
+``latest`` may change content at a future date.
+
+Cloud-init uses the ``2016-01-01`` version.
+
+You can list the versions available to your instance with:
+
+.. code-block:: shell-session
+
+    $ curl http://100.100.100.200/
+    2016-01-01
+    latest
+
+Metadata
+^^^^^^^^
+Instance metadata can be queried at
+``http://100.100.100.200/2016-01-01/meta-data``
+
+.. code-block:: shell-session
+
+    $ curl http://100.100.100.200/2016-01-01/meta-data
+    dns-conf/
+    eipv4
+    hostname
+    image-id
+    instance-id
+    instance/
+    mac
+    network-type
+    network/
+    ntp-conf/
+    owner-account-id
+    private-ipv4
+    public-keys/
+    region-id
+    serial-number
+    source-address
+    sub-private-ipv4-list
+    vpc-cidr-block
+    vpc-id
+
+Userdata
+^^^^^^^^
+If provided, user-data will appear at
+``http://100.100.100.200/2016-01-01/user-data``.
+If no user-data is provided, this will return a 404.
+
+.. code-block:: shell-session
+
+    $ curl http://100.100.100.200/2016-01-01/user-data
+    #!/bin/sh
+    echo "Hello World."
+
+.. vi: textwidth=78