[PATCH v2 00/11] reuse NetworkManager connection profiles to set up kdump network

[Coiby Xu]

Currently, kexec-tools parses legacy ifcfg-* configuration files or
NetworkManager .nmconnection connection profiles to build up dracut
command line parameters like ip=. Then dracut parses these parameters and
runs nm-initrd-generator to generate NetworkManager connection profiles.
Taking a bonding network as an example, nm-initrd-generator generates two
connections as follows,
  $ /usr/libexec/nm-initrd-generator -s -- bootdev=mybond0 rd.neednet kdumpnic=mybond0
bond=mybond0:kdump-eth0
  
  *** Connection 'mybond0' ***
  
  [connection]
  id=mybond0
  uuid=ed87d02b-dd44-4f0e-8b11-37db7e89bb48
  interface-name=mybond0
  
  [ipv4]
  dhcp-timeout=90
  ...
  
  *** Connection 'kdump-eth0' ***
  
  [connection]
  id=kdump-eth0
  uuid=ed6a7448-b5f8-4f8a-b718-3e24ea1c924b
  type=ethernet
  interface-name=kdump-eth0
  master=ed87d02b-dd44-4f0e-8b11-37db7e89bb48
  slave-type=bond
  wait-device-timeout=60000
		...
  

Later in kdump initrd, dracut starts NetworkManager to activate these
profiles to bring up the network connections. This way of setting up
kdump network is tedious, error-prone and unnecessary. A better way is
to directly copy the needed connection profiles to initrd. A potential
benefit of this approach for the users is they can simply edit the
connection profile directly like changing ipv4.dhcp-timeout instead of
being forced to use the hard-coded value enforced by
nm-initrd-generator.

This patch set reuses NetworkManager connection profiles to setup kdump
network. It also reduces the memory consumption of network drivers and
fix other issues at the same time. A machine could have multiple network
drivers and a network driver may manage multiple NICs. It's possible
kdump may only need one NIC. In this case, there is no need to install
unneeded network drivers or bring up unneeded NICs.

There are cases where a NIC may have a different name in the kdump
kernel. Currently, kexec-tools creates udev rules to rename NIC to have
a consistent name. With the new approach, we can simply ask NM to match
the connection profile by MAC address instead.

Here are the bug list that addressed by this patch set,
  - Bug 1962421 - [RHEL-9]"eth0: Failed to rename network interface 3 from
'eth0' to 'kdump-eth0': File exists"
  - Bug 2064708 - kdump: mkdumprd: failed to make kdump initrd for bridge network on z15
z/vm
		- bugs related to OOM caused by network driver
		  - Bug 1950282 - shutdown those unneeded network interfaces to save memory for kdump
		  - Bug 1958587 - the kdump initramfs includes unnecessary NIC drivers for SSH/NFS
dumping target
		  - Bug 1890021 - be2net is using too much memory during kdump
		  - Bug 1662202 - [RHEL-8.1] aarch64: hpe-apache crashkernel OOM when dump to network
targe

Note this patch set is available for review on 
https://github.com/coiby/kexec-tools/pull/9

v2:
- removes useless cat which also avoids SC2013
- fix code format issue and shellcheck warning
- squash four commits "set up kdump network {bridge,vlan,bridge,team} by directly
  copying NM connection profile to initrd" to switch to the new approach
		all at once to avoid confusion and causing trouble for git bisection
- fix several issues found by Philipp
		- add missing reference
		- use an array instead of supress shellchek SC2086 warning
		- use $_netifs instead of $_netif_allowlist to intruct NM to only
		  manage specified NICs
		- multiple typos
		- use nmcli --get-values to get type first then construct MAC field
		  name
		- get rid of the extra indentation
		- s/uniq_name/unique_name/

v1: 
- refactor complex kdump_copy_nmconnection_file [Philipp]
- clean up temporary file in a trap [Philipp]
- improve sed [Philipp]
- use long name consistently [Philipp]
- use nmcli -t, --terse option to suppress printing of the header [Philipp]
- don't pass kdumpip to initrd [Kairui]
- address the case where kdump_install_net is called multiple times like
  fence kdump
  - call kdump_install_nm_netif_allowlist after all kdump_install_net
		  calls have been finished
- ask NM to match a connection profile to a physical NIC by MAC address
- stop treating vlan specially when its parent interface is a physical NIC
- don't add unused NIC drivers to kdump initrd 
- fix the error of "/etc/NetworkManager/system-connections/*.nmconnection" not
exist
  grep: /etc/NetworkManager/system-connections/*.nmconnection: No such file or directory
- redirect the messages of nmcli to ddebug
- use "grep -s" to get rid of the following warnings
  grep:
/var/tmp/dracut.6tqUm0/initramfs//etc/NetworkManager/system-connections/*.nmconnection: No
such file or directory
  grep: /etc/sysconfig/network-scripts/ifcfg-*: No such file or directory
  grep: /etc/NetworkManager/system-connections/*.nmconnection: No such file or directory

Coiby Xu (11):
  add function to copy NetworkManage connection profile to the initramfs
  clone NM connection profiles to support legacy ifcfg automatically
  ask NM to wait the network device to be available
  stop dracut 35network-manager from running nm-initrd-generator
  fix error for vlan over team network interface
  set up kdump network by directly copying NM connection profile to
    initrd
  clean up unneeded code after copying .nmconnection to initrd
  reduce kdump memory consumption by not letting NetworkManager manage
    unneeded network interfaces
  reduce kdump memory consumption by only installing needed NIC drivers
  address the cases where a NIC has a different name in kdump kernel
  simplify setup_znet by copying connection profile to initrd

 dracut-kdump.sh            |  39 +-
 dracut-module-setup.sh     | 483 ++++++++----------
 dracut-module-setup.sh.fix | 994 +++++++++++++++++++++++++++++++++++++
 kdump-lib-initramfs.sh     |  14 +
 mkdumprd                   |   2 +-
 5 files changed, 1243 insertions(+), 289 deletions(-)
 create mode 100755 dracut-module-setup.sh.fix

-- 
2.37.1