radosgw – rados REST gateway

Synopsis

radosgw

Description

radosgw is an HTTP REST gateway for the RADOS object store, a part of the Ceph distributed storage system. It is implemented as a FastCGI module using libfcgi, and can be used in conjunction with any FastCGI capable web server.

Options

-c ceph.conf``, --conf``=ceph.conf

Use ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to determine monitor addresses during startup.

-m monaddress[:port]

Connect to specified monitor (instead of looking through ceph.conf).

-i ID``, --id ID

Set the ID portion of name for radosgw

-n TYPE.ID``, --name TYPE.ID

Set the rados user name for the gateway (eg. client.radosgw.gateway)

--cluster NAME

Set the cluster name (default: ceph)

-d

Run in foreground, log to stderr

-f

Run in foreground, log to usual location

--rgw-socket-path``=path

Specify a unix domain socket path.

--rgw-region``=region

The region where radosgw runs

--rgw-zone``=zone

The zone where radosgw runs

Configuration

Earlier RADOS Gateway had to be configured with Apache and mod_fastcgi. Now, mod_proxy_fcgi module is used instead of mod_fastcgi. mod_proxy_fcgi works differently than a traditional FastCGI module. This module requires the service of mod_proxy which provides support for the FastCGI protocol. So, to be able to handle FastCGI protocol, both mod_proxy and mod_proxy_fcgi have to be present in the server. Unlike mod_fastcgi, mod_proxy_fcgi cannot start the application process. Some platforms have fcgistarter for that purpose. However, external launching of application or process management may be available in the FastCGI application framework in use.

Apache can be configured in a way that enables mod_proxy_fcgi to be used with localhost tcp or through unix domain socket. mod_proxy_fcgi that doesn’t support unix domain socket such as the ones in Apache 2.2 and earlier versions of Apache 2.4, needs to be configured for use with localhost tcp. Later versions of Apache like Apache 2.4.9 or later support unix domain socket and as such they allow for the configuration with unix domain socket instead of localhost tcp.

The following steps show the configuration in Ceph’s configuration file i.e, /etc/ceph/ceph.conf and the gateway configuration file i.e, /etc/httpd/conf.d/rgw.conf (RPM-based distros) or /etc/apache2/conf-available/rgw.conf (Debian-based distros) with localhost tcp and through unix domain socket:

  1. For distros with Apache 2.2 and early versions of Apache 2.4 that use localhost TCP and do not support Unix Domain Socket, append the following contents to /etc/ceph/ceph.conf:

    1. [client.radosgw.gateway]
    2. host = {hostname}
    3. keyring = /etc/ceph/ceph.client.radosgw.keyring
    4. rgw socket path = ""
    5. log file = /var/log/ceph/client.radosgw.gateway.log
    6. rgw frontends = fastcgi socket_port=9000 socket_host=0.0.0.0
    7. rgw print continue = false

  2. Add the following content in the gateway configuration file:

    For Debian/Ubuntu add in /etc/apache2/conf-available/rgw.conf:

    1. <VirtualHost *:80>
    2. ServerName localhost
    3. DocumentRoot /var/www/html
    5. ErrorLog /var/log/apache2/rgw_error.log
    6. CustomLog /var/log/apache2/rgw_access.log combined
    8. # LogLevel debug
    10. RewriteEngine On
    12. RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
    14. SetEnv proxy-nokeepalive 1
    16. ProxyPass / fcgi://localhost:9000/
    18. </VirtualHost>

    For CentOS/RHEL add in /etc/httpd/conf.d/rgw.conf:

    1. <VirtualHost *:80>
    2. ServerName localhost
    3. DocumentRoot /var/www/html
    5. ErrorLog /var/log/httpd/rgw_error.log
    6. CustomLog /var/log/httpd/rgw_access.log combined
    8. # LogLevel debug
    10. RewriteEngine On
    12. RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
    14. SetEnv proxy-nokeepalive 1
    16. ProxyPass / fcgi://localhost:9000/
    18. </VirtualHost>

  3. For distros with Apache 2.4.9 or later that support Unix Domain Socket, append the following configuration to /etc/ceph/ceph.conf:

    1. [client.radosgw.gateway]
    2. host = {hostname}
    3. keyring = /etc/ceph/ceph.client.radosgw.keyring
    4. rgw socket path = /var/run/ceph/ceph.radosgw.gateway.fastcgi.sock
    5. log file = /var/log/ceph/client.radosgw.gateway.log
    6. rgw print continue = false

  4. Add the following content in the gateway configuration file:

    For CentOS/RHEL add in /etc/httpd/conf.d/rgw.conf:

    1. <VirtualHost *:80>
    2. ServerName localhost
    3. DocumentRoot /var/www/html
    5. ErrorLog /var/log/httpd/rgw_error.log
    6. CustomLog /var/log/httpd/rgw_access.log combined
    8. # LogLevel debug
    10. RewriteEngine On
    12. RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
    14. SetEnv proxy-nokeepalive 1
    16. ProxyPass / unix:///var/run/ceph/ceph.radosgw.gateway.fastcgi.sock|fcgi://localhost:9000/
    18. </VirtualHost>

    Please note, Apache 2.4.7 does not have Unix Domain Socket support in it and as such it has to be configured with localhost tcp. The Unix Domain Socket support is available in Apache 2.4.9 and later versions.

  5. Generate a key for radosgw to use for authentication with the cluster.

    1. ceph-authtool -C -n client.radosgw.gateway --gen-key /etc/ceph/keyring.radosgw.gateway
    2. ceph-authtool -n client.radosgw.gateway --cap mon 'allow rw' --cap osd 'allow rwx' /etc/ceph/keyring.radosgw.gateway

  6. Add the key to the auth entries.

    1. ceph auth add client.radosgw.gateway --in-file=keyring.radosgw.gateway

  7. Start Apache and radosgw.

    Debian/Ubuntu:

    1. sudo /etc/init.d/apache2 start
    2. sudo /etc/init.d/radosgw start

    CentOS/RHEL:

    1. sudo apachectl start
    2. sudo /etc/init.d/ceph-radosgw start

Usage Logging

radosgw maintains an asynchronous usage log. It accumulates statistics about user operations and flushes it periodically. The logs can be accessed and managed through radosgw-admin.

The information that is being logged contains total data transfer, total operations, and total successful operations. The data is being accounted in an hourly resolution under the bucket owner, unless the operation was done on the service (e.g., when listing a bucket) in which case it is accounted under the operating user.

Following is an example configuration:

  1. [client.radosgw.gateway]
  2.     rgw enable usage log = true
  3.     rgw usage log tick interval = 30
  4.     rgw usage log flush threshold = 1024
  5.     rgw usage max shards = 32
  6.     rgw usage max user shards = 1

The total number of shards determines how many total objects hold the usage log information. The per-user number of shards specify how many objects hold usage information for a single user. The tick interval configures the number of seconds between log flushes, and the flush threshold specify how many entries can be kept before resorting to synchronous flush.

Availability

radosgw is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at http://ceph.com/docs for more information.

See also

ceph(8) radosgw-admin(8)