fix(nspawn-container): Retry 0-setup-system.sh on failure (#586)

Other system processes can acquire a dpkg frontend lock on startup that
will cause the downloaded package install to fail. The setup script
continues without exiting and machinectl is not found.

This change forces the script to exit early on error, and adds 5 retries
to the systemd unit at 30s intervals.

Signed-off-by: Micah Hausler <hausler.m@gmail.com>

nspawn-container/scripts/0-setup-system.sh

@@ -2,6 +2,8 @@
 # This script installs systemd-container if it's not installed.
 # Also links any containers from /data/custom/machines to /var/lib/machines.
 
+set -e
+
 if ! dpkg -l systemd-container | grep ii >/dev/null; then
     if ! apt -y install systemd-container debootstrap; then
         yes | dpkg -i /data/custom/dpkg/*.deb

nspawn-container/scripts/setup-system.service

@@ -2,11 +2,13 @@
 Description=Setup custom container service
 Wants=network-online.target
 After=network-online.target
+StartLimitBurst=5
 
 [Service]
 Type=oneshot
 ExecStart=/data/on_boot.d/0-setup-system.sh
 RemainAfterExit=yes
+RestartSec=30
 
 [Install]
 WantedBy=multi-user.target