doc: Add config info to ec2, openstack and cloudstack datasource docs

Also document instance-data.json on the top-level datasource topic page.

1 files changed, 30 insertions, 0 deletions

diff --git a/doc/rtd/topics/datasources/ec2.rst b/doc/rtd/topics/datasources/ec2.rst
index 3bc66e17..64c325d8 100644
--- a/doc/rtd/topics/datasources/ec2.rst
+++ b/doc/rtd/topics/datasources/ec2.rst
@@ -60,4 +60,34 @@ To see which versions are supported from your cloud provider use the following U
     ...
     latest
 
+
+
+Configuration
+-------------
+The following configuration can be set for the datasource in system
+configuration (in `/etc/cloud/cloud.cfg` or `/etc/cloud/cloud.cfg.d/`).
+
+The settings that may be configured are:
+
+ * **metadata_urls**: This list of urls will be searched for an Ec2
+   metadata service. The first entry that successfully returns a 200 response
+   for <url>/<version>/meta-data/instance-id will be selected.
+   (default: ['http://169.254.169.254', 'http://instance-data:8773']).
+ * **max_wait**:  the maximum amount of clock time in seconds that should be
+   spent searching metadata_urls.  A value less than zero will result in only
+   one request being made, to the first in the list. (default: 120)
+ * **timeout**: the timeout value provided to urlopen for each individual http
+   request.  This is used both when selecting a metadata_url and when crawling
+   the metadata service. (default: 50)
+
+An example configuration with the default values is provided below:
+
+.. sourcecode:: yaml
+
+  datasource:
+   Ec2:
+    metadata_urls: ["http://169.254.169.254:80", "http://instance-data:8773"]
+    max_wait: 120
+    timeout: 50
+
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