Overview

Ceph is a distributed storage and network file system designed to provide excellent performance, reliability and scalability.

This charm deploys the RADOS Gateway, a S3 and Swift compatible HTTP gateway for online object storage on-top of a ceph cluster.

Usage

In order to use this charm, it is assumed that you have already deployed a ceph storage cluster using the 'ceph' charm with something like this::

juju deploy -n 3 --config ceph.yaml ceph

To deploy the RADOS gateway simple do::

juju deploy ceph-radosgw
juju add-relation ceph-radosgw ceph

You can then directly access the RADOS gateway by exposing the service::

juju expose ceph-radosgw

The gateway can be accessed over port 80 (as show in juju status exposed ports).

Access

Note that you will need to login to one of the service units supporting the ceph charm to generate some access credentials::

juju ssh ceph/0 \
  'sudo radosgw-admin user create --uid="ubuntu" --display-name="Ubuntu Ceph"'

For security reasons the ceph-radosgw charm is not set up with appropriate permissions to administer the ceph cluster.

Keystone Integration

Ceph >= 0.55 integrates with Openstack Keystone for authentication of Swift requests.

This is enabled by relating the ceph-radosgw service with keystone::

juju deploy keystone
juju add-relation keystone ceph-radosgw

If you try to relate the radosgw to keystone with an earlier version of ceph the hook will error out to let you know.

HA/Clustering

There are two mutually exclusive high availability options: using virtual IP(s) or DNS. In both cases, a relationship to hacluster is required which provides the corosync back end HA functionality.

To use virtual IP(s) the clustered nodes must be on the same subnet such that the VIP is a valid IP on the subnet for one of the node's interfaces and each node has an interface in said subnet. The VIP becomes a highly-available API endpoint.

At a minimum, the config option 'vip' must be set in order to use virtual IP HA. If multiple networks are being used, a VIP should be provided for each network, separated by spaces. Optionally, vip_iface or vip_cidr may be specified.

To use DNS high availability there are several prerequisites. However, DNS HA does not require the clustered nodes to be on the same subnet. Currently the DNS HA feature is only available for MAAS 2.0 or greater environments. MAAS 2.0 requires Juju 2.0 or greater. The clustered nodes must have static or "reserved" IP addresses registered in MAAS. The DNS hostname(s) must be pre-registered in MAAS before use with DNS HA.

At a minimum, the config option 'dns-ha' must be set to true and at least one of 'os-public-hostname', 'os-internal-hostname' or 'os-internal-hostname' must be set in order to use DNS HA. One or more of the above hostnames may be set.

The charm will throw an exception in the following circumstances: If neither 'vip' nor 'dns-ha' is set and the charm is related to hacluster If both 'vip' and 'dns-ha' are set as they are mutually exclusive If 'dns-ha' is set and none of the os-{admin,internal,public}-hostname(s) are set

Network Space support

This charm supports the use of Juju Network Spaces, allowing the charm to be bound to network space configurations managed directly by Juju. This is only supported with Juju 2.0 and above.

API endpoints can be bound to distinct network spaces supporting the network separation of public, internal and admin endpoints.

To use this feature, use the --bind option when deploying the charm:

juju deploy ceph-radosgw --bind "public=public-space internal=internal-space admin=admin-space"

alternatively these can also be provided as part of a juju native bundle configuration:

ceph-radosgw:
  charm: cs:ceph-radosgw
  num_units: 1
  bindings:
    public: public-space
    admin: admin-space
    internal: internal-space

NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.

NOTE: Existing deployments using os-*-network configuration options will continue to function; these options are preferred over any network space binding provided if set.

Multi-Site replication

Overview

This charm supports configuration of native replication between Ceph RADOS gateway deployments.

This is supported both within a single model and between different models using cross-model relations.

By default either ceph-radosgw deployment will accept write operations.

Deployment

NOTE: example bundles for the us-west and us-east models can be found in the bundles subdirectory of the ceph-radosgw charm.

NOTE: switching from a standalone deployment to a multi-site replicated deployment is not supported.

To deploy in this configuration ensure that the following configuration options are set on the ceph-radosgw charm deployments - in this example rgw-us-east and rgw-us-west are both instances of the ceph-radosgw charm:

rgw-us-east:
  realm: replicated
  zonegroup: us
  zone: us-east
rgw-us-west:
  realm: replicated
  zonegroup: us
  zone: us-west

When deploying with this configuration the ceph-radosgw applications will deploy into a blocked state until the master/slave (cross-model) relation is added.

Typically each ceph-radosgw deployment will be associated with a separate ceph cluster at different physical locations - in this example the deployments are in different models ('us-east' and 'us-west').

One ceph-radosgw application acts as the initial master for the deployment - setup the master relation endpoint as the provider of the offer for the cross-model relation:

juju offer -m us-east rgw-us-east:master

The cross-model relation offer can then be consumed in the other model and related to the slave ceph-radosgw application:

juju consume -m us-west admin/us-east.rgw-us-east
juju add-relation -m us-west rgw-us-west:slave rgw-us-east:master

Once the relation has been added the realm, zonegroup and zone configuration will be created in the master deployment and then synced to the slave deployment.

The current sync status can be validated from either model:

juju ssh -m us-east ceph-mon/0
sudo radosgw-admin sync status
          realm 142eb39c-67c4-42b3-9116-1f4ffca23964 (replicated)
      zonegroup 7b69f059-425b-44f5-8a21-ade63c2034bd (us)
           zone 4ee3bc39-b526-4ac9-a233-64ebeacc4574 (us-east)
  metadata sync no sync (zone is master)
      data sync source: db876cf0-62a8-4b95-88f4-d0f543136a07 (us-west)
                        syncing
                        full sync: 0/128 shards
                        incremental sync: 128/128 shards
                        data is caught up with source

Once the deployment is complete, the default zone and zonegroup can optionally be tidied using the 'tidydefaults' action:

juju run-action -m us-west --unit rgw-us-west/0 tidydefaults

This operation is not reversible.

Failover/Recovery

In the event that the site hosting the zone which is the master for metadata (in this example us-east) has an outage, the master metadata zone must be failed over to the slave site; this operation is performed using the 'promote' action:

juju run-action -m us-west --wait rgw-us-west/0 promote

Once this action has completed, the slave site will be the master for metadata updates and the deployment will accept new uploads of data.

Once the failed site has been recovered it will resync and resume as a slave to the promoted master site (us-west in this example).

The master metadata zone can be failed back to its original location once resync has completed using the 'promote' action:

juju run-action -m us-east --wait rgw-us-east/0 promote

Read/write vs Read-only

By default all zones within a deployment will be read/write capable but only the master zone can be used to create new containers.

Non-master zones can optionally be marked as read-only by using the 'readonly' action:

juju run-action -m us-east --wait rgw-us-east/0 readonly

a zone that is currently read-only can be switched to read/write mode by either promoting it to be the current master or by using the 'readwrite' action:

juju run-action -m us-east --wait rgw-us-east/0 readwrite