Apply static IP changes without a reboot (#1723)

Related tiny-pilot/tinypilot-pro#1172

This PR introduces the `apply-static-ip` script that replaces the use of
`reboot` to allow the static IP settings to take effect.

This code was originally reviewed in
tiny-pilot/tinypilot-pro#1175 before being
backported here.

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debian-pkg/opt/tinypilot-privileged/scripts/apply-static-ip

@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# Immediately apply the current static IP config to the device.
+
+# Exit on first failure.
+set -e
+
+# Echo commands before executing them, by default to stderr.
+set -x
+
+# Exit on unset variable.
+set -u
+
+# Ignore hangup signals to avoid exiting the shell when the network interface
+# is flushed and a new IP is assigned. This was an issue when running the script
+# manually via a remote shell.
+trap '' HUP
+ip address flush dev eth0
+systemctl restart \
+  dhcpcd.service

debian-pkg/opt/tinypilot-privileged/scripts/set-static-ip

@@ -137,8 +137,8 @@ fi
 # Exit on unset variable.
 set -u
 
-# Use the unset-static-ip script to remove any existing configuration.
-"${SCRIPT_DIR}/unset-static-ip" --quiet
+# Remove any existing automated configuration.
+"${SCRIPT_DIR}/strip-marker-sections" "${CONFIG_FILE}"
 
 # Only proceed if no other configuration exists.
 if grep -q "^interface ${INTERFACE}" "${CONFIG_FILE}" ; then
@@ -157,11 +157,11 @@ fi
   echo "${MARKER_END}"
 } | sudo tee --append "${CONFIG_FILE}" > /dev/null
 
-# Changes require a reboot so prompt the user.
+# Apply changes.
+"${SCRIPT_DIR}/apply-static-ip"
+
 echo "A static local IP address has been set."
 echo "  Interface: ${INTERFACE}"
 echo "  IP Address: ${IP_ADDRESS}"
 echo "  Routers: ${ROUTERS}"
 echo "  Domain Name Servers: ${DNS}"
-echo ""
-echo "Reboot your TinyPilot device to apply the changes."

debian-pkg/opt/tinypilot-privileged/scripts/unset-static-ip

@@ -61,9 +61,9 @@ set -u
 # Remove any existing marker sections from the config file.
 "${SCRIPT_DIR}/strip-marker-sections" /etc/dhcpcd.conf
 
-# Changes require a reboot so prompt the user.
+# Apply changes.
+"${SCRIPT_DIR}/apply-static-ip"
+
 if [[ "${QUIET}" == "false" ]] ; then
   echo "Any changes made by the set-static-ip script have been reverted."
-  echo ""
-  echo "Reboot your TinyPilot device to apply the changes."
 fi