Allow undionly.kpxe boot option to be overridden
As an operator, I may wish to provide DHCP boot options for hosts not managed by bifrost using the bifrost dnsmasq server. If a dhcp-boot configuration option is provided to dnsmasq via a file in /etc/dnsmasq.d/, and the server is not booted via iPXE, it will be overridden by the undionly.kpxe option added by bifrost in /etc/dnsmasq.conf. This occurs because the negated tag match !ipxe used in the /undionly.kpxe dhcp-boot entry will match all hosts not using iPXE. The dhcp-boot entries are processed in order and the last matching entry wins. Since the config-dir option appears before the dhcp-boot options, user-provided options are processed first and are therefore overridden. The solution here is fairly simple - use a positive match for the ipxe tag: dhcp-boot=tag:ipxe,http://host:port/boot.ipxe dhcp-boot=/undionly.kpxe An entry with a tag will always win over the entry without a tag specified, so it is now possible to add a rule to override undionly.kpxe. Change-Id: Ic0637e14504def73fbc0333eee9dc2456c57c32e Closes-Bug: #1675367
This commit is contained in:
Mark Goddard
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7417ff36e4
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@ -1,3 +1,53 @@
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Configuring the integrated DHCP server
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======================================
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Setting static DHCP assignments with the integrated DHCP server
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---------------------------------------------------------------
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You can set up a static DHCP reservation using the ``ipv4_address`` parameter
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and setting the ``inventory_dhcp`` setting to a value of ``true``. This will
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result in the first MAC address defined in the list of hardware MAC addresses
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to receive a static address assignment in dnsmasq.
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Forcing DNS to resolve to ipv4_address
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--------------------------------------
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dnsmasq will resolve all entries to the IP assigned to each server in
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the leases file. However, this IP will not always be the desired one, if you
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are working with multiple networks.
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To force DNS to always resolve to ``ipv4_address`` please set the
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``inventory_dns`` setting to a value of ``true``. This will result in each
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server to resolve to ``ipv4_address`` by explicitly using address capabilities
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of dnsmasq.
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Extending dnsmasq configuration
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-------------------------------
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Bifrost manages the dnsmasq configuration file in ``/etc/dnsmasq.conf``. It is
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not recommended to make manual modifications to this file after it has been
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written. dnsmasq supports the use of additional configuration files in
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``/etc/dnsmasq.d``, allowing extension of the dnsmasq configuration provided by
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bifrost. It is possible to use this mechanism provide additional DHCP options
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to systems managed by ironic, or even to create a DHCP boot environment for
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systems not managed by ironic. For example, create a file
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``/etc/dnsmasq.d/example.conf`` with the following contents::
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dhcp-match=set:<tag>,<match criteria>
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dhcp-boot=tag:<tag>,<boot options>
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The tag, match critera and boot options should be modified for your
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environment. Here we use dnsmasq tags to match against hosts that we want to
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manage. dnsmasq will use the last matching tagged ``dhcp-boot`` option for a
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host or an untagged default ``dhcp-boot`` option if there were no matches.
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These options will be inserted at the ``conf-dir=/etc/dnsmasq.d`` line of the
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dnsmasq configuration file. Once configured, send the ``HUP`` signal to
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dnsmasq, which will cause it to reread its configuration::
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killall -HUP dnsmasq
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Using Bifrost with your own DHCP server
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=======================================
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The possibility exists that a user may already have a Dynamic Host
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Configuration Protocol (DHCP) server on their network.
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@ -23,8 +73,8 @@ depending on the environment configuration.
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dnsmasq::
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dhcp-match=set:ipxe,175 # iPXE sends a 175 option.
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dhcp-boot=tag:!ipxe,/undionly.kpxe,<TFTP Server Hostname>,<TFTP Server IP Address>
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dhcp-boot=http://<Bifrost Host IP Address>:8080/boot.ipxe
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dhcp-boot=tag:ipxe,http://<Bifrost Host IP Address>:8080/boot.ipxe
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dhcp-boot=/undionly.kpxe,<TFTP Server Hostname>,<TFTP Server IP Address>
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Internet Systems Consortium DHCPd::
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@ -53,22 +103,3 @@ in a trusted environment.
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+-------------+ +-----------+
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|Ironic Server| | Server |
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+-------------+ +-----------+
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Setting static DHCP assignments with the integrated DHCP server
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---------------------------------------------------------------
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You can set up a static DHCP reservation using the ``ipv4_address`` parameter
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and setting the ``inventory_dhcp`` setting to a value of ``true``. This will
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result in the first MAC address defined in the list of hardware MAC addresses
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to receive a static address assignment in dnsmasq.
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Forcing DNS to resolve to ipv4_address
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--------------------------------------
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dnsmasq will resolve all entries to the IP assigned to each server in
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the leases file. However, this IP will not always be the desired one, if you
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are working with multiple networks.
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To force DNS to always resolve to ``ipv4_address`` please set the
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``inventory_dns`` setting to a value of ``true``. This will result in each
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server to resolve to ``ipv4_address`` by explicitly using address capabilities
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of dnsmasq.
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@ -317,8 +317,6 @@ If you wish to include an extra element into the IPA disk image, such as a
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custom hardware manager, you can pass the variable ``ipa_extra_dib_elements``
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as a space-separated list of elements. This defaults to an empty string.
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Use Bifrost with your own DHCP server
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=====================================
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.. include:: deploy/dhcp.rst
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Use Bifrost with Keystone
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@ -94,13 +94,15 @@ dhcp-userclass=set:gpxe,"gPXE"
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dhcp-boot=tag:gpxe,/ipxe.pxe
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dhcp-match=set:ipxe,175 # iPXE sends a 175 option.
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dhcp-boot=tag:!ipxe,/undionly.kpxe
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{% if testing | bool == true %}
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dhcp-boot=http://192.168.122.1:{{ file_url_port }}/boot.ipxe
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dhcp-boot=tag:ipxe,http://192.168.122.1:{{ file_url_port }}/boot.ipxe
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{% else %}
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dhcp-boot=http://{{ hostvars[inventory_hostname]['ansible_' + ans_network_interface]['ipv4']['address'] }}:{{ file_url_port }}/boot.ipxe
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dhcp-boot=tag:ipxe,http://{{ hostvars[inventory_hostname]['ansible_' + ans_network_interface]['ipv4']['address'] }}:{{ file_url_port }}/boot.ipxe
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{% endif %}
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# Catch-all boot options used when no other boot options are matched.
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dhcp-boot=/undionly.kpxe
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{% if testing | bool == true %}
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log-queries
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log-dhcp
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17
releasenotes/notes/override-dhcp-boot-6659585b75d58757.yaml
Normal file
17
releasenotes/notes/override-dhcp-boot-6659585b75d58757.yaml
Normal file
@ -0,0 +1,17 @@
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---
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fixes:
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- |
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Allows ``undionly.kpxe`` boot option to be overridden.
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As an operator, I may wish to provide DHCP boot options for hosts not
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managed by bifrost using the bifrost dnsmasq server.
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Previously, if a ``dhcp-boot`` configuration option was provided to dnsmasq
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via a file in ``/etc/dnsmasq.d/``, and the server was not booted via iPXE,
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the option would have been overridden by the ``undionly.kpxe`` option added
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by bifrost in ``/etc/dnsmasq.conf``.
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Bifrost now supports user-provided ``dhcp-boot`` options in
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``/etc/dnsmasq.d``. These should be specified with an appropriate set of
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tags to match against to ensure that the rule overrides the default rule
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configured by bifrost.
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