Add support for Arch Linux in render-cloudcfg

 - Detect Arch Linux and set variant accordingly in `system_info()`
 - Allow setting render-cloudcfg variant parameter to 'arch'
 - Adjust some basic settings for Arch Linux in the cloud.cfg.tmpl

The template might need some additional Arch-specific tweaks in the
future, but at least for now the generated config works and contains
the most relevant modules.

Also:
- Sort distro variant lists when adding Arch
- Add debian to known variants in render-cloudcfg

cloudinit/util.py

@@ -656,7 +656,8 @@ def system_info():
     var = 'unknown'
     if system == "linux":
         linux_dist = info['dist'][0].lower()
-        if linux_dist in ('centos', 'debian', 'fedora', 'rhel', 'suse'):
+        if linux_dist in (
+                'arch', 'centos', 'debian', 'fedora', 'rhel', 'suse'):
             var = linux_dist
         elif linux_dist in ('ubuntu', 'linuxmint', 'mint'):
             var = 'ubuntu'

config/cloud.cfg.tmpl

@@ -137,7 +137,7 @@ cloud_final_modules:
 # (not accessible to handlers/transforms)
 system_info:
    # This will affect which distro class gets used
-{% if variant in ["centos", "debian", "fedora", "rhel", "suse", "ubuntu", "freebsd"] %}
+{% if variant in ["arch", "centos", "debian", "fedora", "freebsd", "rhel", "suse", "ubuntu"] %}
    distro: {{ variant }}
 {% else %}
    # Unknown/fallback distro.
@@ -185,14 +185,16 @@ system_info:
          primary: http://ports.ubuntu.com/ubuntu-ports
          security: http://ports.ubuntu.com/ubuntu-ports
    ssh_svcname: ssh
-{% elif variant in ["centos", "rhel", "fedora", "suse"] %}
+{% elif variant in ["arch", "centos", "fedora", "rhel", "suse"] %}
    # Default user name + that default users groups (if added/used)
    default_user:
      name: {{ variant }}
      lock_passwd: True
      gecos: {{ variant }} Cloud User
 {% if variant == "suse" %}
      groups: [cdrom, users]
+{% elif variant == "arch" %}
+     groups: [wheel, users]
 {% else %}
      groups: [wheel, adm, systemd-journal]
 {% endif %}

tools/render-cloudcfg

@@ -4,7 +4,8 @@ import argparse
 import os
 import sys
 
-VARIANTS = ["freebsd", "centos", "fedora", "rhel", "suse", "ubuntu", "unknown"]
+VARIANTS = ["arch", "centos", "debian", "fedora", "freebsd", "rhel", "suse",
+            "ubuntu", "unknown"]
 
 if "avoid-pep8-E402-import-not-top-of-file":
     _tdir = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))