Change NixOS to dynamic

distros/nixos/23.05/x86_64.pkrvars.hcl

@@ -1,15 +0,0 @@
-distro = "nixos"
-version = "23.05"
-iso = {
-	url = "https://channels.nixos.org/nixos-23.05/latest-nixos-minimal-x86_64-linux.iso"
-	checksum = "e2a0bc2be3b6638692393a19435838d464149914dbd942010e31a3c8c84c82d5"
-}
-boot_command = [
-  "<tab><wait> net.ifnames=0<wait> <wait>bi<wait>osdevnames=0<enter>",
-  "<wait60>",  # Wait for system to come up?
-  "curl -o /tmp/install.sh http://{{ .HTTPIP }}:{{ .HTTPPort }}/install.sh<enter>",
-  "<wait>",
-  "sudo bash /tmp/install.sh {{ .HTTPPort }} {{ .HTTPIP }}<enter>"
-]
-http_directory = "distros/nixos/23.05/http/"
-boot_wait = "5s"

distros/nixos/23.05/x86_64.pkrvars.hcl.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+set -exo pipefail
+
+# Name of the file to write out
+name="${0%.sh}"
+
+version="23.05"
+
+# Base URL
+base="https://channels.nixos.org/nixos-${version}/latest-nixos-minimal-x86_64-linux.iso"
+
+# Working directory
+tmp="$(mktemp -d)"
+checksums="${tmp}/checksums"
+
+# Read the SHA256 sum value
+curl -L -o "${checksums}" "${base}.sha256"
+until curl -f -L -o "${checksums}" "${base}.sha256"; do
+	sleep 1
+done
+sha="$(cat "${checksums}" | grep minimal | cut -d' ' -f 1)"
+
+# Write out HCL file
+cat << EOF > "${name}"
+distro = "nixos"
+version = "${version}"
+iso = {
+	url = "${base}"
+	checksum = "${sha}"
+}
+boot_command = [
+  "<tab><wait> net.ifnames=0<wait> <wait>bi<wait>osdevnames=0<enter>",
+  "<wait60>",  # Wait for system to come up?
+  "curl -o /tmp/install.sh http://{{ .HTTPIP }}:{{ .HTTPPort }}/install.sh<enter>",
+  "<wait>",
+  "sudo bash /tmp/install.sh {{ .HTTPPort }} {{ .HTTPIP }}<enter>"
+]
+http_directory = "distros/nixos/23.05/http/"
+boot_wait = "5s"
+EOF
+
+rm -r "${tmp}"