Continue adding datasource docs.

Add a base set for ec2 and datasource none.

1 files changed, 103 insertions, 10 deletions

diff --git a/doc/rtd/topics/datasources.rst b/doc/rtd/topics/datasources.rst
index c2354ace..59c58805 100644
--- a/doc/rtd/topics/datasources.rst
+++ b/doc/rtd/topics/datasources.rst
@@ -20,32 +20,52 @@ The current interface that a datasource object must provide is the following:
 
 .. sourcecode:: python
     
+    # returns a mime multipart message that contains
+    # all the various fully-expanded components that
+    # were found from processing the raw userdata string
+    # - when filtering only the mime messages targeting
+    #   this instance id will be returned (or messages with
+    #   no instance id)
     def get_userdata(self, apply_filter=False)
     
-    @property
-    def launch_index(self)
+    # returns the raw userdata string (or none)
+    def get_userdata_raw(self)
     
+    # returns a integer (or none) which can be used to identify
+    # this instance in a group of instances which are typically
+    # created from a single command, thus allowing programatic
+    # filtering on this launch index (or other selective actions)
     @property
-    def is_disconnected(self)
-    
-    def get_userdata_raw(self)
+    def launch_index(self)
     
     # the data sources' config_obj is a cloud-config formated
     # object that came to it from ways other than cloud-config
     # because cloud-config content would be handled elsewhere
     def get_config_obj(self)
     
+    #returns a list of public ssh keys
     def get_public_ssh_keys(self)
     
+    # translates a device 'short' name into the actual physical device
+    # fully qualified name (or none if said physical device is not attached
+    # or does not exist)
     def device_name_to_device(self, name)
     
+    # gets the locale string this instance should be applying 
+    # which typically used to adjust the instances locale settings files
     def get_locale(self)
     
     @property
     def availability_zone(self)
     
+    # gets the instance id that was assigned to this instance by the 
+    # cloud provider or when said instance id does not exist in the backing
+    # metadata this will return 'iid-datasource'
     def get_instance_id(self)
     
+    # gets the fully qualified domain name that this host should  be using
+    # when configuring network or hostname releated settings, typically
+    # assigned either by the cloud provider or the user creating the vm
     def get_hostname(self, fqdn=False)
     
     def get_package_mirror_info(self)
@@ -54,7 +74,65 @@ The current interface that a datasource object must provide is the following:
 EC2
 ---------------------------
 
-TBD
+The EC2 datasource is the oldest and most widely used datasource that cloud-init
+supports. This datasource interacts with a *magic* ip that is provided to the 
+instance by the cloud provider. Typically this ip is ``169.254.169.254`` of which
+at this ip a http server is provided to the instance so that the instance can make
+calls to get instance userdata and instance metadata.
+
+Metadata is accessible via the following URL:
+
+::
+    
+    GET http://169.254.169.254/2009-04-04/meta-data/
+    ami-id
+    ami-launch-index
+    ami-manifest-path
+    block-device-mapping/
+    hostname
+    instance-id
+    instance-type
+    local-hostname
+    local-ipv4
+    placement/
+    public-hostname
+    public-ipv4
+    public-keys/
+    reservation-id
+    security-groups
+
+Userdata is accessible via the following URL:
+
+::
+    
+    GET http://169.254.169.254/2009-04-04/user-data
+    1234,fred,reboot,true | 4512,jimbo, | 173,,,
+
+Note that there are multiple versions of this data provided, cloud-init
+by default uses **2009-04-04** but newer versions can be supported with
+relative ease (newer versions have more data exposed, while maintaining
+backward compatibility with the previous versions). 
+
+To see which versions are supported from your cloud provider use the following URL:
+
+::
+    
+    GET http://169.254.169.254/
+    1.0
+    2007-01-19
+    2007-03-01
+    2007-08-29
+    2007-10-10
+    2007-12-15
+    2008-02-01
+    2008-09-01
+    2009-04-04
+    ...
+    latest
+        
+**Note:** internally in cloudinit the `boto`_ library used to fetch the instance
+userdata and instance metadata, feel free to check that library out, it provides
+many other useful EC2 functionality.
 
 ---------------------------
 Config Drive
@@ -78,22 +156,37 @@ No cloud
 MAAS
 ---------------------------
 
-TBD
+*TODO*
+
+For now see: http://maas.ubuntu.com/
 
 ---------------------------
 CloudStack
 ---------------------------
 
-TBD
+*TODO*
 
 ---------------------------
 OVF
 ---------------------------
 
-See: https://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/files/head:/doc/sources/ovf/
+*TODO*
+
+For now see: https://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/files/head:/doc/sources/ovf/
 
 ---------------------------
 Fallback/None
 ---------------------------
 
-TBD
+This is the fallback datasource when no other datasource can be selected. It is
+the equivalent of a *empty* datasource in that it provides a empty string as userdata
+and a empty dictionary as metadata. It is useful for testing as well as for when
+you do not have a need to have an actual datasource to meet your instance 
+requirements (ie you just want to run modules that are not concerned with any
+external data). It is typically put at the end of the datasource search list
+so that if all other datasources are not matched, then this one will be so that
+the user is not left with an inaccessible instance.
+
+**Note:** the instance id that this datasource provides is ``iid-datasource-none``.
+
+.. _boto: http://docs.pythonboto.org/en/latest/