Reproducer/Verification for SRU to Jammy,
based on strace delay injection on read().

Uploading to jammy.
Attaching debdiff for reference.

...

Launch a VM with the Jammy daily live server:

	$ wget https://cdimage.ubuntu.com/ubuntu-server/jammy/daily-live/current/jammy-live-server-amd64.iso

	$ ISO=jammy-live-server-amd64.iso
	$ VM=casper-jammy
	$ virt-install  --name $VM --cdrom $ISO --vcpus 2 --memory 2048 --disk none --osinfo ubuntu-stable-latest 

Press e to edit, append "break=init console=ttyS0", press ctrl-x, close window.

Open the serial console and chroot:

	$ virsh console $VM
	...
	(initramfs) chroot /root /bin/bash

Test strace delay injection:

	# time strace --trace read cat /dev/null
	read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3206\2\0\0\0\0\0"..., 832) = 832
	read(3, "", 131072)                     = 0
	+++ exited with 0 +++

	real	0m0.041s
	user	0m0.009s
	sys	0m0.030s

	# time strace --trace read --inject read:delay_enter=5s cat /dev/null
	read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3206\2\0\0\0\0\0"..., 832) = 832 (DELAYED)
	read(3, "", 131072)                     = 0 (DELAYED)
	+++ exited with 0 +++

	real	0m10.041s
	user	0m0.010s
	sys	0m0.033s

Modify the casper-md5check service:

	# sed -i '/^ExecStart=/ s,=,=/usr/bin/strace --inject read:delay_enter=60s ,' /usr/lib/systemd/system/casper-md5check.service

	# cat /usr/lib/systemd/system/casper-md5check.service
	[Unit]
	Description=casper-md5check Verify Live ISO checksums

	[Service]
	Type=oneshot
	ExecStart=/usr/bin/strace --inject read:delay_enter=60s /usr/lib/casper/casper-md5check /cdrom /cdrom/md5sum.txt
	RemainAfterExit=yes

	[Install]
	WantedBy=multi-user.target

Exit and wait; the issue happens:

	# exit
	(initramfs) exit

	...

	Ubuntu 22.04.1 ubuntu-server ttyS0


	connecting...
	waiting for cloud-init... /

	<10 minutes later>

	================================================================================
	  Serial                                                              [ Help ]
	================================================================================

	  As the installer is running on a serial console, it has started in basic
	  mode, using only the ASCII character set and black and white colours.

	   ┌────────────────────────────────────────────────────────────────────────┐
	   │                                                                        │
	   │  cloud-init failed to complete after 10 minutes of waiting. This       │
	   │  suggests a bug, which we would appreciate help understanding.  If     │
	   │  you could file a bug at                                               │
	   │  https://bugs.launchpad.net/subiquity/+filebug and attach the          │
	   │  contents of /var/log, it would be most appreciated.                   │
	   │                                                                        │
	   │                         [ Switch to a shell ]                          │
	   │                         [ Close             ]                          │
	   │                                                                        │
	   └────────────────────────────────────────────────────────────────────────┘


		                  [ Continue in rich mode  > ]
		                  [ Continue in basic mode > ]


...

Similarly, repeat, this time with test packages from ppa:mfo/lp1986781:

...

Open the serial console and chroot:


	$ virsh console $VM
	...
	(initramfs) chroot /root /bin/bash

Install the test package:

	# dhclient enp1s0
	# wget https://launchpad.net/~mfo/+archive/ubuntu/lp1986781/+build/25512466/+files/casper_1.470.2_amd64.deb
	# dpkg -i casper_*.deb

Modify the casper-md5check service:

	# sed -i '/^ExecStart=/ s,=,=/usr/bin/strace --inject read:delay_enter=60s ,' /usr/lib/systemd/system/casper-md5check.service

	# cat /usr/lib/systemd/system/casper-md5check.service
	Description=casper-md5check Verify Live ISO checksums
	After=multi-user.target

	[Service]
	Type=oneshot
	ExecStart=/usr/bin/strace --inject read:delay_enter=60s /usr/lib/casper/casper-md5check /cdrom /cdrom/md5sum.txt
	RemainAfterExit=yes

	[Install]
	WantedBy=multi-user.target

Exit and wait; the issue does _not_ happen anymore:

	# exit
	(initramfs) exit

...

	Ubuntu 22.04.1 ubuntu-server ttyS0


	connecting...
	waiting for cloud-init... /

	<some seconds later>



	================================================================================
	  Serial                                                              [ Help ]
	================================================================================

	  As the installer is running on a serial console, it has started in basic
	  mode, using only the ASCII character set and black and white colours.

	  If you are connecting from a terminal emulator such as gnome-terminal that
	  supports unicode and rich colours you can switch to "rich mode" which uses
	  unicode, colours and supports many languages.

	  You can also connect to the installer over the network via SSH, which will
	  allow use of rich mode.



		                  [ Continue in rich mode  > ]
		                  [ Continue in basic mode > ]
		                  [ View SSH instructions    ]


Checking the casper-md5sum service is still running:

	Help > Enter shell.

	# systemctl status casper-md5check.service --no-pager | grep 'Active:'
	     Active: activating (start) since Mon 2023-01-23 18:56:50 UTC; 3min 26s ago

And it should not be a problem, as its start timeout is not limited.

	# systemctl show casper-md5check.service | grep -i timeout
	TimeoutStartUSec=infinity
	TimeoutStopUSec=1min 30s
	TimeoutAbortUSec=1min 30s
	TimeoutStartFailureMode=terminate
	TimeoutStopFailureMode=terminate
	TimeoutCleanUSec=infinity
	JobTimeoutUSec=infinity
	JobRunningTimeoutUSec=infinity
	JobTimeoutAction=none

Quit, cleanup the VM.

	Press ctrl-]

	$ virsh destroy $VM
	$ virsh undefine $VM