diskimage-builder/diskimage_builder/elements/dhcp-all-interfaces/README.rst
Julia Kreger 5f01bd5d61 Use internal dhcp client for centos 9-stream and beyond
All indication in CI is that Centos Stream9's use of dhclient
appears to point to compatability issues when interacting with
dnsmasq. However, this doesn't appear to be the issue with the
internal dhcp client. As such, lets constraint the RH default
so that it no longer applies to Centos 9-stream.

I've also added a documentation entry for DIB_DHCP_CLIENT which
was previously undocumented.

As an aside, I've already reached out to RH's NetworkManager team
regarding this, but root cause is not entirely understood at this
point.

Change-Id: I235f75b385a8b0348c8fe064038c51409f8722c4
Story: 2010109
Task: 45677
2022-06-28 11:02:03 -07:00

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===================
dhcp-all-interfaces
===================
Autodetect network interfaces during boot and configure them for DHCP
The rationale for this is that we are likely to require multiple
network interfaces for use cases such as baremetal and there is no way
to know ahead of time which one is which, so we will simply run a
DHCP client on all interfaces with real MAC addresses (except lo) that
are visible on the first boot.
On non-Gentoo based distributions the script
/usr/local/sbin/dhcp-all-interfaces.sh will be called early in each
boot and will scan available network interfaces and ensure they are
configured properly before networking services are started.
On Gentoo based distributions we will install the dhcpcd package and
ensure the service starts at boot. This service automatically sets
up all interfaces found via dhcp and/or dhcpv6 (or SLAAC).
Environment Variables
---------------------
DIB_DHCP_TIMEOUT
:Required: No
:Default: 30
:Description: Amount of time in seconds that the systemd service(or dhclient)
will wait to get an address. Should be increased in networks such as
Infiniband.
:Example: DIB_DHCP_TIMEOUT=300
DIB_DHCP_NETWORK_MANAGER_AUTO
:Required: No
:Default: false
:Description: When NetworkManager is detected, and this is set to true the
dhcp-all-interfaces service will not be installed. Only the NetworkManager
configuration will be added. NetworkManager is quite capable to do automatic
interface configuration. NetworkManager will by default try to
auto-configure any interface with no configuration, it will use DHCP for
IPv4 and Router Advertisements to decide how to initialize IPv6.
:Example: DIB_DHCP_NETWORK_MANAGER_AUTO=true
DIB_DHCP_CLIENT
:Required: no
:Default: internal
:Description: When NetworkManager is in use, this setting conveys which DHCP
client is in use for acquiring a DHCP address for the node. In some specific
cases, where known that dhclient is the tested or most compatible default,
specifically for Centos 7, 8, and 8-Stream, as well as derived distributions.
Otherwise, the "internal" dhcp client is the default.
:Example: DIB_DHCP_CLIENT