Restful Module

Restful Module

RESTful module 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 set mgr mgr/restful/$name/server_addr $IP
ceph config set mgr mgr/restful/$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 set mgr mgr/restful/server_addr $IP
ceph config set mgr 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.

Creating an API User

To create an API user, please run the following command:

ceph restful create-key <username>

Replace <username> with the desired name of the user. For example, to create a user named api:

$ ceph restful create-key api
52dffd92-a103-4a10-bfce-5b60f48f764e

The UUID generated from ceph restful create-key api acts as the key for the user.

To list all of your API keys, please run the following command:

ceph restful list-keys

The ceph restful list-keys command will output in JSON:

{
      "api": "52dffd92-a103-4a10-bfce-5b60f48f764e"
}

You can use curl in order to test your user with the API. Here is an example:

curl -k https://api:52dffd92-a103-4a10-bfce-5b60f48f764e@<ceph-mgr>:<port>/server

In the case above, we are using GET to fetch information from the server endpoint.

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.

Available methods

You can navigate to the /doc endpoint for full list of available endpoints and HTTP methods implemented for each endpoint.

For example, if you want to use the PATCH method of the /osd/<id> endpoint to set the state up of the OSD id 1, you can use the following curl command:

echo -En '{"up": true}' | curl --request PATCH --data @- --silent --insecure --user <user> 'https://<ceph-mgr>:<port>/osd/1'

or you can use python to do so:

$ python
>> import requests
>> result = requests.patch(
       'https://<ceph-mgr>:<port>/osd/1',
       json={"up": True},
       auth=("<user>", "<password>")
   )
>> print result.json()

Some of the other endpoints implemented in the restful module include

/config/cluster: GET
/config/osd: GET, PATCH
/crush/rule: GET
/mon: GET
/osd: GET
/pool: GET, POST
/pool/<arg>: DELETE, GET, PATCH
/request: DELETE, GET, POST
/request/<arg>: DELETE, GET
/server: GET

The `/request` endpoint

You can use the /request endpoint to poll the state of a request you scheduled with any DELETE, POST or PATCH method. These methods are by default asynchronous since it may take longer for them to finish execution. You can modify this behaviour by appending ?wait=1 to the request url. The returned request will then always be completed.

The POST method of the /request method provides a passthrough for the ceph mon commands as defined in src/mon/MonCommands.h. Let’s consider the following command:

COMMAND("osd ls " \
        "name=epoch,type=CephInt,range=0,req=false", \
        "show all OSD ids", "osd", "r", "cli,rest")

The prefix is osd ls. The optional argument’s name is epoch and it is of type CephInt, i.e. integer. This means that you need to do the following POST request to schedule the command:

$ python
>> import requests
>> result = requests.post(
       'https://<ceph-mgr>:<port>/request',
       json={'prefix': 'osd ls', 'epoch': 0},
       auth=("<user>", "<password>")
   )
>> print result.json()

RESTful module