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47 lines
1.7 KiB
ReStructuredText
47 lines
1.7 KiB
ReStructuredText
===============================
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Looking op Monitors through DNS
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===============================
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Since version 11.0.0 RADOS supports looking up Monitors through DNS.
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This way daemons and clients do not require a *mon host* configuration directive in their ceph.conf configuration file.
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Using DNS SRV TCP records clients are able to look up the monitors.
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This allows for less configuration on clients and monitors. Using a DNS update clients and daemons can be made aware of changes in the monitor topology.
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By default clients and daemons will look for the TCP service called *ceph-mon* which is configured by the *mon_dns_srv_name* configuration directive.
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Example
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-------
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When the DNS search domain is set to *example.com* a DNS zone file might contain the following elements.
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First, create records for the Monitors, either IPv4 (A) or IPv6 (AAAA).
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::
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mon1.example.com. AAAA 2001:db8::100
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mon2.example.com. AAAA 2001:db8::200
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mon3.example.com. AAAA 2001:db8::300
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mon1.example.com. A 192.168.0.1
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mon2.example.com. A 192.168.0.2
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mon3.example.com. A 192.168.0.3
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With those records now existing we can create the SRV TCP records with the name *ceph-mon* pointing to the three Monitors.
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::
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_ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon1.example.com.
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_ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon2.example.com.
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_ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon3.example.com.
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In this case the Monitors are running on port *6789*.
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The current implementation in clients and daemons does *not* honor nor respect the weight or priority set in SRV records.
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All records returned will be treated equally in a Round Robin fashion.
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