Install LibreTranslate in a virtualenv

Ubuntu 24.04's system Python is externally managed (PEP 668) and refuses pip installs. Also bump LibreTranslate from 1.3.8 to 1.9.6, since the former pulls ctranslate2 2.24.0 which has no Python 3.12 wheels.

site-cookbooks/kosmos-mastodon/recipes/libretranslate.rb

@@ -5,9 +5,10 @@
 
 build_essential
 
-version = "1.3.8"
+version = "1.9.6"
+venv    = "/opt/libretranslate/venv"
 
-%w{ python3 python3-pip python3-setuptools python3-dev }.each do |pkg|
+%w{ python3 python3-pip python3-setuptools python3-dev python3-venv }.each do |pkg|
   apt_package pkg
 end
 
@@ -17,19 +18,26 @@ user "libretranslate" do
   manage_home true
 end
 
+# LibreTranslate is installed into a dedicated virtualenv. Ubuntu 24.04's
+# system Python is externally managed (PEP 668) and refuses `pip install`.
+bash "create_libretranslate_venv" do
+  code "sudo -u libretranslate python3 -m venv #{venv}"
+  not_if { ::File.exist?("#{venv}/bin/pip") }
+end
+
 bash "install_libretranslate" do
-  code "sudo -u libretranslate pip3 install --user --prefer-binary libretranslate==#{version}"
+  code "sudo -u libretranslate #{venv}/bin/pip install --prefer-binary libretranslate==#{version}"
   action :run
-  not_if { `sudo -u libretranslate pip3 list |grep libretranslate`.split(' ')[1] == version rescue false }
+  not_if "#{venv}/bin/pip show libretranslate 2>/dev/null | grep -q 'Version: #{version}'"
   notifies :restart, "service[libretranslate]", :delayed
 end
 
-languages = `sudo -u libretranslate /opt/libretranslate/.local/bin/argospm search`
+languages = `sudo -u libretranslate #{venv}/bin/argospm search`
 languages.each_line do |line|
   lang = line.split(':').first
 
   bash "install_lt_#{lang}" do
-    code "sudo -u libretranslate /opt/libretranslate/.local/bin/argospm install #{lang}"
+    code "sudo -u libretranslate #{venv}/bin/argospm install #{lang}"
     action :nothing
   end
 end
@@ -46,7 +54,7 @@ systemd_unit "libretranslate.service" do
       User: "libretranslate",
       Group: "libretranslate",
       WorkingDirectory: "/opt/libretranslate/",
-      ExecStart: "/opt/libretranslate/.local/bin/libretranslate --host 127.0.0.1 --port 5000 --disable-files-translation",
+      ExecStart: "#{venv}/bin/libretranslate --host 127.0.0.1 --port 5000 --disable-files-translation",
       Restart: "always"
     },
     Install: {