Recommend using dhcp-sequential-ip in the dnsmasq configuration

Introspection naturally happens in large bulks, after which it's inactive.
Small pool for DHCP addresses means that we'll have conflicts due to how
dnsmasq distributes them by default - using hashing. This option tells dnsmasq
to allocate IP addresses sequentially instead to avoid these conflicts.
See https://bugzilla.redhat.com/show_bug.cgi?id=1301659 for detailed analysis.

The drawback of this option is that long-running clients may switch IP
addresses if their lease expires. This is not a concern for short introspection
process.

This change may obsolete the need in the delay between 2 introspections.

Change-Id: Id277f3d31902bee16d3b048dbde5c34af905f0bc
changes/00/287100/4
Dmitry Tantsur 7 years ago
parent e8ecb99122
commit 2f8e105b4b

@ -224,6 +224,7 @@ interface=$IRONIC_INSPECTOR_INTERFACE
bind-interfaces
dhcp-range=$IRONIC_INSPECTOR_DHCP_RANGE
dhcp-boot=pxelinux.0
dhcp-sequential-ip
EOF
}

@ -125,6 +125,12 @@ As for PXE boot environment, you'll need:
enable-tftp
tftp-root={TFTP ROOT, e.g. /tftpboot}
dhcp-boot=pxelinux.0
dhcp-sequential-ip
.. note::
``dhcp-sequential-ip`` is used because otherwise a lot of nodes booting
simultaneously cause conflicts - the same IP address is suggested to
several nodes.
* You have to install and configure one of 2 available ramdisks: simple
bash-based (see `Using simple ramdisk`_) or more complex based on

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