Comment 9 for bug 1854694

Verified on a AMD64 platform. The watchdog timer settings are all applied immediately.

[snaps]
$ snap list
Name Version Rev Tracking Publisher Notes
customized-gadget 18-1.1 1 latest/stable ****** gadget
customized-kernel 4.15.0-1003 1 latest/stable ****** kernel
core18 20200427 1754 latest/stable canonical✓ base
snapd 2.45~pre2+git1841.gd17b92f 7695 latest/edge canonical✓ snapd

[verification]
1. snapd has set the watchdog timer settings carried by the gadget snap properly at first-boot
  $ sudo snap get system -d
  {
   "seed": {
    "loaded": true
   },
   "watchdog": {
    "runtime-timeout": "1m",
    "shutdown-timeout": "10m"
   }
  }

2. The systemd has corresponding watchdog timer settings
  $ sudo systemctl show |grep -i watchdog
  RuntimeWatchdogUSec=1min
  ShutdownWatchdogUSec=10min
  ServiceWatchdogs=yes

3. I saw the systemd said it was re-executing in the journal log
$ sudo journalctl -b |grep -i reexec -A3
May 08 09:13:04 localhost systemd[1]: Reexecuting.
May 08 09:13:04 localhost kernel: systemd: 65 output lines suppressed due to ratelimiting
May 08 09:13:04 localhost systemd[1]: systemd 237 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid)
May 08 09:13:04 localhost systemd[1]: Detected architecture x86-64.