restful plugin
==============

RESTful plugin offers the REST API access to the status of the cluster
over an SSL-secured connection.

Enabling
--------

The *restful* module is enabled with::

  ceph mgr module enable restful

You will also need to configure an SSL certificate below before the
API endpoint is available.  By default the module will accept HTTPS
requests on port ``8003`` on all IPv4 and IPv6 addresses on the host.

Securing
--------

All connections to *restful* are secured with SSL.  You can generate a
self-signed certificate with the command::

  ceph restful create-self-signed-cert

Note that with a self-signed certificate most clients will need a flag
to allow a connection and/or suppress warning messages.  For example,
if the ``ceph-mgr`` daemon is on the same host,::

  curl -k https://localhost:8003/

To properly secure a deployment, a certificate that is signed by the
organization's certificate authority should be used.  For example, a key pair
can be generated with a command similar to::

  openssl req -new -nodes -x509 \
    -subj "/O=IT/CN=ceph-mgr-restful" \
    -days 3650 -keyout restful.key -out restful.crt -extensions v3_ca

The ``restful.crt`` should then be signed by your organization's CA
(certificate authority).  Once that is done, you can set it with::

  ceph config-key set mgr/restful/$name/crt -i restful.crt
  ceph config-key set mgr/restful/$name/key -i restful.key

where ``$name`` is the name of the ``ceph-mgr`` instance (usually the
hostname). If all manager instances are to share the same certificate,
you can leave off the ``$name`` portion::

  ceph config-key set mgr/restful/crt -i restful.crt
  ceph config-key set mgr/restful/key -i restful.key


Configuring IP and port
-----------------------

Like any other RESTful API endpoint, *restful* binds to an IP and
port.  By default, the currently active ``ceph-mgr`` daemon will bind
to port 8003 and any available IPv4 or IPv6 address on the host.

Since each ``ceph-mgr`` hosts its own instance of *restful*, it may
also be necessary to configure them separately. The IP and port
can be changed via the configuration key facility::

  ceph config-key set mgr/restful/$name/server_addr $IP
  ceph config-key set mgr/restful/$name/server_port $PORT

where ``$name`` is the ID of the ceph-mgr daemon (usually the hostname).

These settings can also be configured cluster-wide and not manager
specific.  For example,::

  ceph config-key set mgr/restful/server_addr $IP
  ceph config-key set mgr/restful/server_port $PORT

If the port is not configured, *restful* will bind to port ``8003``.
If the address it not configured, the *restful* will bind to ``::``,
which corresponds to all available IPv4 and IPv6 addresses.

Load balancer
-------------

Please note that *restful* will *only* start on the manager which
is active at that moment. Query the Ceph cluster status to see which
manager is active (e.g., ``ceph mgr dump``).  In order to make the
API available via a consistent URL regardless of which manager
daemon is currently active, you may want to set up a load balancer
front-end to direct traffic to whichever manager endpoint is
available.