Chapter 5. Multi-Site

The procedure for installing Ceph Object Gateway is identical to the procedure described in the Red Hat Ceph Storage Installation Guide for Ubuntu but with this difference: proceed to configure the zones BEFORE starting the Ceph Object Gateway daemons to avoid the need to remove default zones and pools.

Ansible can install and configure Ceph Object Gateways for use with a Ceph Storage cluster. So for a simple configuration, add Ceph Object Gateways to your Ansible configuration. For multi-site and multi-site group deployments, you should have an Ansible configuration for each zone.

If you install Ceph Object Gateway with Ansible, the Ansible playbooks will handle the initial configuration for you. To install the Ceph Object Gateway with Ansible, add your hosts to the /etc/ansible/hosts file. Add the Ceph Object Gateway hosts under an [rgws] section to identify their roles to Ansible. If your hosts have sequential naming, you may use a range. For example:

[rgws]
<rgw-host-name-1>
<rgw-host-name-2>
<rgw-host-name[3..10]>

Once you have added the hosts, you may rerun your Ansible playbooks.

A realm contains the multi-site configuration of zone groups and zones and also serves to enforce a globally unique namespace within the realm.

Create a new realm for the multi-site configuration by opening a command line interface on a host identified to serve in the master zone group and zone. Then, execute the following:

[root@master-zone]# radosgw-admin realm create --rgw-realm={realm-name} [--default]

For example:

[root@master-zone]# radosgw-admin realm create --rgw-realm=movies --default

If the cluster will have a single realm, specify the --default flag. If --default is specified, radosgw-admin will use this realm by default. If --default is not specified, adding zone-groups and zones requires specifying either the --rgw-realm flag or the --realm-id flag to identify the realm when adding zone groups and zones.

After creating the realm, radosgw-admin will echo back the realm configuration. For example:

{
    "id": "0956b174-fe14-4f97-8b50-bb7ec5e1cf62",
    "name": "movies",
    "current_period": "1950b710-3e63-4c41-a19e-46a715000980",
    "epoch": 1
}

A realm must have at least one zone group, which will serve as the master zone group for the realm.

Create a new master zone group for the multi-site configuration by opening a command line interface on a host identified to serve in the master zone group and zone. Then, execute the following:

[root@master-zone]# radosgw-admin zonegroup create --rgw-zonegroup={name} --endpoints={url} [--rgw-realm={realm-name}|--realm-id={realm-id}] --master --default

For example:

[root@master-zone]# radosgw-admin zonegroup create --rgw-zonegroup=us --endpoints=http://rgw1:80 --rgw-realm=movies --master --default

If the realm will only have a single zone group, specify the --default flag. If --default is specified, radosgw-admin will use this zone group by default when adding new zones. If --default is not specified, adding zones will require either the --rgw-zonegroup flag or the --zonegroup-id flag to identify the zone group when adding or modifying zones.

After creating the master zone group, radosgw-admin will echo back the zone group configuration. For example:

{
    "id": "f1a233f5-c354-4107-b36c-df66126475a6",
    "name": "us",
    "api_name": "us",
    "is_master": "true",
    "endpoints": [
        "http:\/\/rgw1:80"
    ],
    "hostnames": [],
    "hostnames_s3webzone": [],
    "master_zone": "",
    "zones": [],
    "placement_targets": [],
    "default_placement": "",
    "realm_id": "0956b174-fe14-4f97-8b50-bb7ec5e1cf62"
}

Create a new master zone for the multi-site configuration by opening a command line interface on a host identified to serve in the master zone group and zone. Then, execute the following:

[root@master-zone]# radosgw-admin zone create \
                            --rgw-zonegroup={zone-group-name} \
                            --rgw-zone={zone-name} \
                            --master --default \
                            --endpoints={http://fqdn}[,{http://fqdn}

For example:

[root@master-zone]# radosgw-admin zone create --rgw-zonegroup=us \
                            --rgw-zone=us-east \
                            --master --default \
                            --endpoints={http://fqdn}[,{http://fqdn}

Delete the default zone if it exists. Make sure to remove it from the default zone group first.

[root@master-zone]# radosgw-admin zonegroup remove --rgw-zonegroup=default --rgw-zone=default
[root@master-zone]# radosgw-admin period update --commit
[root@master-zone]# radosgw-admin zone delete --rgw-zone=default
[root@master-zone]# radosgw-admin period update --commit
[root@master-zone]# radosgw-admin zonegroup delete --rgw-zonegroup=default
[root@master-zone]# radosgw-admin period update --commit

Finally, delete the default pools in your Ceph storage cluster if they exist.

# rados rmpool default.rgw.control default.rgw.control --yes-i-really-really-mean-it
# rados rmpool default.rgw.data.root default.rgw.data.root --yes-i-really-really-mean-it
# rados rmpool default.rgw.gc default.rgw.gc --yes-i-really-really-mean-it
# rados rmpool default.rgw.log default.rgw.log --yes-i-really-really-mean-it
# rados rmpool default.rgw.users.uid default.rgw.users.uid --yes-i-really-really-mean-it

The ceph-radosgw daemons must authenticate before pulling realm and period information. In the master zone, create a system user to facilitate authentication between daemons.

[root@master-zone]# radosgw-admin user create --uid="{user-name}" --display-name="{Display Name}" --system

For example:

[root@master-zone]# radosgw-admin user create --uid="synchronization-user" --display-name="Synchronization User" --system

Make a note of the access_key and secret_key, as the secondary zones will require them to authenticate with the master zone.

Finally, add the system user to the master zone.

[root@master-zone]# radosgw-admin zone modify --rgw-zone=us-east --access-key={access-key} --secret={secret}
[root@master-zone]# radosgw-admin period update --commit

After updating the master zone configuration, update the period.

# radosgw-admin period update --commit

Update the Ceph configuration file on master zone hosts by adding the rgw_zone configuration option and the name of the master zone to the instance entry.

[client.rgw.{instance-name}]
...
rgw_zone={zone-name}

For example:

[client.rgw.rgw1]
host = rgw1
rgw frontends = "civetweb port=80"
rgw_zone=us-east

On the object gateway host, start and enable the Ceph Object Gateway service:

$ sudo systemctl start ceph-radosgw@rgw.`hostname -s`
$ sudo systemctl enable ceph-radosgw@rgw.`hostname -s`

If the service is already running, restart the service instead of starting and enabling it:

$ sudo systemctl restart ceph-radosgw@rgw.`hostname -s`

Using the URL path, access key and secret of the master zone in the master zone group, pull the realm to the host. To pull a non-default realm, specify the realm using the --rgw-realm or --realm-id configuration options.

# radosgw-admin realm pull --url={url-to-master-zone-gateway} --access-key={access-key} --secret={secret}

If this realm is the default realm or the only realm, make the realm the default realm.

# radosgw-admin realm default --rgw-realm={realm-name}

Using the URL path, access key and secret of the master zone in the master zone group, pull the period to the host. To pull a period from a non-default realm, specify the realm using the --rgw-realm or --realm-id configuration options.

# radosgw-admin period pull --url={url-to-master-zone-gateway} --access-key={access-key} --secret={secret}

Create a secondary zone for the multi-site configuration by opening a command line interface on a host identified to serve the secondary zone. Specify the zone group ID, the new zone name and an endpoint for the zone. DO NOT use the --master or --default flags. In Red Hat Ceph Storage 2, all zones run in an active-active configuration by default; that is, a gateway client may write data to any zone and the zone will replicate the data to all other zones within the zone group. If the secondary zone should not accept write operations, specify the --read-only flag to create an active-passive configuration between the master zone and the secondary zone. Additionally, provide the access_key and secret_key of the generated system user stored in the master zone of the master zone group. Execute the following:

[root@second-zone]# radosgw-admin zone create --rgw-zonegroup={zone-group-name}\
                           --rgw-zone={zone-name} --endpoints={url} \
                           --access-key={system-key} --secret={secret}\
                           --endpoints=http://{fqdn}:80 \
                           [--read-only]

For example:

[root@second-zone]# radosgw-admin zone create --rgw-zonegroup=us \
                            --rgw-zone=us-west \
                            --access-key={system-key} --secret={secret} \
                            --endpoints=http://rgw2:80

Delete the default zone if needed.

[root@second-zone]# radosgw-admin zone delete --rgw-zone=default

Finally, delete the default pools in your Ceph storage cluster if needed.

# rados rmpool default.rgw.control default.rgw.control --yes-i-really-really-mean-it
# rados rmpool default.rgw.data.root default.rgw.data.root --yes-i-really-really-mean-it
# rados rmpool default.rgw.gc default.rgw.gc --yes-i-really-really-mean-it
# rados rmpool default.rgw.log default.rgw.log --yes-i-really-really-mean-it
# rados rmpool default.rgw.users.uid default.rgw.users.uid --yes-i-really-really-mean-it

Update the Ceph configuration file on the secondary zone hosts by adding the rgw_zone configuration option and the name of the secondary zone to the instance entry.

[client.rgw.{instance-name}]
...
rgw_zone={zone-name}

For example:

[client.rgw.rgw2]
host = rgw2
rgw frontends = "civetweb port=80"
rgw_zone=us-west

After updating the master zone configuration, update the period.

# radosgw-admin period update --commit

On the object gateway host, start and enable the Ceph Object Gateway service:

$ sudo systemctl start ceph-radosgw@rgw.`hostname -s`
$ sudo systemctl enable ceph-radosgw@rgw.`hostname -s`

If the service is already running, restart the service instead of starting and enabling it:

$ sudo systemctl restart ceph-radosgw@rgw.`hostname -s`

Once the secondary zone is up and running, check the synchronization status. Synchronization copies users and buckets created in the master zone to the secondary zone.

# radosgw-admin sync status

The output will provide the status of synchronization operations. For example:

realm f3239bc5-e1a8-4206-a81d-e1576480804d (earth)
    zonegroup c50dbb7e-d9ce-47cc-a8bb-97d9b399d388 (us)
         zone 4c453b70-4a16-4ce8-8185-1893b05d346e (us-west)
metadata sync syncing
              full sync: 0/64 shards
              metadata is caught up with master
              incremental sync: 64/64 shards
    data sync source: 1ee9da3e-114d-4ae3-a8a4-056e8a17f532 (us-east)
                      syncing
                      full sync: 0/128 shards
                      incremental sync: 128/128 shards
                      data is caught up with source