Allow the usage of jinja2 templates

This drops the hard requirement on Cheetah. Jinja is a python 2.4->3.x compatible templating engine, allow its optional usage (until we can depreciate cheetah) by allowing for specifying a template file header that can define which template engine to use. If the template file header does not specify a renderer, then assume that that is cheetah. If cheetah is not available, then use a limited builtin renderer on a best effort basis, and log the warning.
2014-07-21 14:54:06 -04:00 · 2014-07-21 14:54:06 -04:00 · aeca294990
commit aeca294990
parent 0d99f66f97 ca61b25a4e
13 changed files with 364 additions and 146 deletions
--- a/2
+++ b/2
@ -7,6 +7,8 @@
 - doc: fix user-groups doc to reference plural ssh-authorized-keys
   (LP: #1327065) [Joern Heissler]
 - fix 'make test' in python 2.6
+ - support jinja2 as a templating engine.  Drop the hard requirement on
+   cheetah.  This helps in python3 effort. (LP: #1219223)
 0.7.5:
 - open 0.7.5
 - Add a debug log message around import failures
--- a/cloudinit/templater.py
+++ b/cloudinit/templater.py
@ -20,13 +20,119 @@
 #    You should have received a copy of the GNU General Public License
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.

-from Cheetah.Template import Template
+import collections
+import re

+try:
+    from Cheetah.Template import Template as CTemplate
+    CHEETAH_AVAILABLE = True
+except (ImportError, AttributeError):
+    CHEETAH_AVAILABLE = False
+
+try:
+    import jinja2
+    from jinja2 import Template as JTemplate
+    JINJA_AVAILABLE = True
+except (ImportError, AttributeError):
+    JINJA_AVAILABLE = False
+
+from cloudinit import log as logging
+from cloudinit import type_utils as tu
 from cloudinit import util

+LOG = logging.getLogger(__name__)
+TYPE_MATCHER = re.compile(r"##\s*template:(.*)", re.I)
+BASIC_MATCHER = re.compile(r'\$\{([A-Za-z0-9_.]+)\}|\$([A-Za-z0-9_.]+)')
+
+
+def basic_render(content, params):
+    """This does simple replacement of bash variable like templates.
+
+    It identifies patterns like ${a} or $a and can also identify patterns like
+    ${a.b} or $a.b which will look for a key 'b' in the dictionary rooted
+    by key 'a'.
+    """
+
+    def replacer(match):
+        # Only 1 of the 2 groups will actually have a valid entry.
+        name = match.group(1)
+        if name is None:
+            name = match.group(2)
+        if name is None:
+            raise RuntimeError("Match encountered but no valid group present")
+        path = collections.deque(name.split("."))
+        selected_params = params
+        while len(path) > 1:
+            key = path.popleft()
+            if not isinstance(selected_params, dict):
+                raise TypeError("Can not traverse into"
+                                " non-dictionary '%s' of type %s while"
+                                " looking for subkey '%s'"
+                                % (selected_params,
+                                   tu.obj_name(selected_params),
+                                   key))
+            selected_params = selected_params[key]
+        key = path.popleft()
+        if not isinstance(selected_params, dict):
+            raise TypeError("Can not extract key '%s' from non-dictionary"
+                            " '%s' of type %s"
+                            % (key, selected_params,
+                               tu.obj_name(selected_params)))
+        return str(selected_params[key])
+
+    return BASIC_MATCHER.sub(replacer, content)
+
+
+def detect_template(text):
+
+    def cheetah_render(content, params):
+        return CTemplate(content, searchList=[params]).respond()
+
+    def jinja_render(content, params):
+        return JTemplate(content,
+                         undefined=jinja2.StrictUndefined,
+                         trim_blocks=True).render(**params)
+
+    if text.find("\n") != -1:
+        ident, rest = text.split("\n", 1)
+    else:
+        ident = text
+        rest = ''
+    type_match = TYPE_MATCHER.match(ident)
+    if not type_match:
+        if not CHEETAH_AVAILABLE:
+            LOG.warn("Cheetah not available as the default renderer for"
+                     " unknown template, reverting to the basic renderer.")
+            return ('basic', basic_render, text)
+        else:
+            return ('cheetah', cheetah_render, text)
+    else:
+        template_type = type_match.group(1).lower().strip()
+        if template_type not in ('jinja', 'cheetah', 'basic'):
+            raise ValueError("Unknown template rendering type '%s' requested"
+                             % template_type)
+        if template_type == 'jinja' and not JINJA_AVAILABLE:
+            LOG.warn("Jinja not available as the selected renderer for"
+                     " desired template, reverting to the basic renderer.")
+            return ('basic', basic_render, rest)
+        elif template_type == 'jinja' and JINJA_AVAILABLE:
+            return ('jinja', jinja_render, rest)
+        if template_type == 'cheetah' and not CHEETAH_AVAILABLE:
+            LOG.warn("Cheetah not available as the selected renderer for"
+                     " desired template, reverting to the basic renderer.")
+            return ('basic', basic_render, rest)
+        elif template_type == 'cheetah' and CHEETAH_AVAILABLE:
+            return ('cheetah', cheetah_render, rest)
+        # Only thing left over is the basic renderer (it is always available).
+        return ('basic', basic_render, rest)
+

 def render_from_file(fn, params):
-    return render_string(util.load_file(fn), params)
+    if not params:
+        params = {}
+    template_type, renderer, content = detect_template(util.load_file(fn))
+    LOG.debug("Rendering content of '%s' using renderer %s", fn, template_type)
+    return renderer(content, params)


 def render_to_file(fn, outfn, params, mode=0644):
@ -37,4 +143,5 @@ def render_to_file(fn, outfn, params, mode=0644):
 def render_string(content, params):
    if not params:
        params = {}
-    return Template(content, searchList=[params]).respond()
+    template_type, renderer, content = detect_template(content)
+    return renderer(content, params)
--- a/packages/bddeb
+++ b/packages/bddeb
@ -31,6 +31,7 @@ PKG_MP = {
    'argparse': 'python-argparse',
    'cheetah': 'python-cheetah',
    'configobj': 'python-configobj',
+    'jinja2': 'python-jinja2',
    'jsonpatch': 'python-jsonpatch | python-json-patch',
    'oauth': 'python-oauth',
    'prettytable': 'python-prettytable',
--- a/packages/brpm
+++ b/packages/brpm
@ -37,6 +37,7 @@ PKG_MP = {
    'redhat': {
        'argparse': 'python-argparse',
        'cheetah': 'python-cheetah',
+        'jinja2': 'python-jinja2',
        'configobj': 'python-configobj',
        'jsonpatch': 'python-jsonpatch',
        'oauth': 'python-oauth',
--- a/requirements.txt
+++ b/requirements.txt
@ -2,6 +2,7 @@

 # Used for untemplating any files or strings with parameters.
 cheetah
+jinja2

 # This is used for any pretty printing of tabular data.
 PrettyTable
--- a/templates/chef_client.rb.tmpl
+++ b/templates/chef_client.rb.tmpl
@ -1,25 +1,25 @@
-#*
-     This file is only utilized if the module 'cc_chef' is enabled in 
-     cloud-config. Specifically, in order to enable it
-     you need to add the following to config:
-       chef:
-         validation_key: XYZ
-         validation_cert: XYZ
-         validation_name: XYZ
-         server_url: XYZ
-*#
+## template:jinja
+{#
+This file is only utilized if the module 'cc_chef' is enabled in 
+cloud-config. Specifically, in order to enable it
+you need to add the following to config:
+  chef:
+    validation_key: XYZ
+    validation_cert: XYZ
+    validation_name: XYZ
+    server_url: XYZ
+-#}
 log_level              :info
 log_location           "/var/log/chef/client.log"
 ssl_verify_mode        :verify_none
-validation_client_name "$validation_name"
+validation_client_name "{{validation_name}}"
 validation_key         "/etc/chef/validation.pem"
 client_key             "/etc/chef/client.pem"
-chef_server_url        "$server_url"
-environment            "$environment"
-node_name              "$node_name"
+chef_server_url        "{{server_url}}"
+environment            "{{environment}}"
+node_name              "{{node_name}}"
 json_attribs           "/etc/chef/firstboot.json"
 file_cache_path        "/var/cache/chef"
 file_backup_path       "/var/backups/chef"
 pid_file               "/var/run/chef/client.pid"
 Chef::Log::Formatter.show_time = true
-
--- a/templates/hosts.debian.tmpl
+++ b/templates/hosts.debian.tmpl
@ -1,19 +1,19 @@
-## This file (/etc/cloud/templates/hosts.tmpl) is only utilized
-## if enabled in cloud-config.  Specifically, in order to enable it
-## you need to add the following to config:
-##    manage_etc_hosts: True
-##
-## Note, double-hash commented lines will not appear in /etc/hosts
-# 
+## template:jinja
+{#
+This file (/etc/cloud/templates/hosts.tmpl) is only utilized
+if enabled in cloud-config.  Specifically, in order to enable it
+you need to add the following to config:
+   manage_etc_hosts: True
+-#}
 # Your system has configured 'manage_etc_hosts' as True.
 # As a result, if you wish for changes to this file to persist
 # then you will need to either
 # a.) make changes to the master file in /etc/cloud/templates/hosts.tmpl
 # b.) change or remove the value of 'manage_etc_hosts' in
 #     /etc/cloud/cloud.cfg or cloud-config from user-data
-# 
-## The value '$hostname' will be replaced with the local-hostname
-127.0.1.1 $fqdn $hostname
+#
+{# The value '{{hostname}}' will be replaced with the local-hostname -#}
+127.0.1.1 {{fqdn}} {{hostname}}
 127.0.0.1 localhost

 # The following lines are desirable for IPv6 capable hosts
@ -23,3 +23,4 @@ ff00::0 ip6-mcastprefix
 ff02::1 ip6-allnodes
 ff02::2 ip6-allrouters
 ff02::3 ip6-allhosts
+
--- a/templates/hosts.redhat.tmpl
+++ b/templates/hosts.redhat.tmpl
@ -1,9 +1,10 @@
-#*
-    This file /etc/cloud/templates/hosts.redhat.tmpl is only utilized
-    if enabled in cloud-config.  Specifically, in order to enable it
-    you need to add the following to config:
-      manage_etc_hosts: True
-*#
+## template:jinja
+{#
+This file /etc/cloud/templates/hosts.redhat.tmpl is only utilized
+if enabled in cloud-config.  Specifically, in order to enable it
+you need to add the following to config:
+  manage_etc_hosts: True
+-#}
 # Your system has configured 'manage_etc_hosts' as True.
 # As a result, if you wish for changes to this file to persist
 # then you will need to either
@ -12,12 +13,12 @@
 #     /etc/cloud/cloud.cfg or cloud-config from user-data
 # 
 # The following lines are desirable for IPv4 capable hosts
-127.0.0.1 ${fqdn} ${hostname} 
+127.0.0.1 {{fqdn}} {{hostname}}
 127.0.0.1 localhost.localdomain localhost
 127.0.0.1 localhost4.localdomain4 localhost4

 # The following lines are desirable for IPv6 capable hosts
-::1 ${fqdn} ${hostname}
+::1 {{fqdn}} {{hostname}}
 ::1 localhost.localdomain localhost
 ::1 localhost6.localdomain6 localhost6

--- a/templates/hosts.suse.tmpl
+++ b/templates/hosts.suse.tmpl
@ -1,9 +1,10 @@
-#*
-    This file /etc/cloud/templates/hosts.suse.tmpl is only utilized
-    if enabled in cloud-config.  Specifically, in order to enable it
-    you need to add the following to config:
-      manage_etc_hosts: True
-*#
+## template:jinja
+{#
+This file /etc/cloud/templates/hosts.suse.tmpl is only utilized
+if enabled in cloud-config.  Specifically, in order to enable it
+you need to add the following to config:
+  manage_etc_hosts: True
+-#}
 # Your system has configured 'manage_etc_hosts' as True.
 # As a result, if you wish for changes to this file to persist
 # then you will need to either
@ -22,3 +23,4 @@ ff00::0 ipv6-mcastprefix
 ff02::1 ipv6-allnodes
 ff02::2 ipv6-allrouters
 ff02::3 ipv6-allhosts
+
--- a/templates/resolv.conf.tmpl
+++ b/templates/resolv.conf.tmpl
@ -1,39 +1,30 @@
-#
+## template:jinja
 # Your system has been configured with 'manage-resolv-conf' set to true.
 # As a result, cloud-init has written this file with configuration data
 # that it has been provided. Cloud-init, by default, will write this file
 # a single time (PER_ONCE).
 #
+{% if nameservers is defined %}
+{% for server in nameservers %}
+nameserver {{server}}
+{% endfor %}

-#if $varExists('nameservers')
-#for $server in $nameservers
-nameserver $server
-#end for
-#end if
-#if $varExists('searchdomains')
-search #slurp
-#for $search in $searchdomains
-$search #slurp
-#end for
+{% endif -%}
+{% if searchdomains is defined %}
+search {% for search in searchdomains %}{{search}} {% endfor %}

-#end if
-#if $varExists('domain')
-domain $domain
-#end if
-#if $varExists('sortlist')
-sortlist #slurp
-#for $sort in $sortlist
-$sort #slurp
-#end for
+{% endif %}
+{% if domain is defined %}
+domain {{domain}}
+{% endif %}
+{% if sortlist is defined %}

-#end if
-#if $varExists('options') or $varExists('flags')
-options #slurp
-#for $flag in $flags
-$flag #slurp
-#end for
-#for $key, $value in $options.items()
-$key:$value #slurp
-#end for
+sortlist {% for sort in sortlist %}{{sort}} {% endfor %}
+{% endif %}
+{% if options is defined or flags is defined %}

-#end if
+options {% for flag in flags %}{{flag}} {% endfor %}
+{% for key, value in options.iteritems() -%}
+ {{key}}:{{value}}
+{% endfor %}
+{% endif %}
--- a/templates/sources.list.debian.tmpl
+++ b/templates/sources.list.debian.tmpl
@ -1,28 +1,32 @@
-\## Note, this file is written by cloud-init on first boot of an instance
-\## modifications made here will not survive a re-bundle.
-\## if you wish to make changes you can:
-\## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
-\##     or do the same in user-data
-\## b.) add sources in /etc/apt/sources.list.d
-\## c.) make changes to template file /etc/cloud/templates/sources.list.debian.tmpl
-\###
+## template:jinja
+## Note, this file is written by cloud-init on first boot of an instance
+## modifications made here will not survive a re-bundle.
+## if you wish to make changes you can:
+## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
+##     or do the same in user-data
+## b.) add sources in /etc/apt/sources.list.d
+## c.) make changes to template file /etc/cloud/templates/sources.list.debian.tmpl
+###

 # See http://www.debian.org/releases/stable/i386/release-notes/ch-upgrading.html
 # for how to upgrade to newer versions of the distribution.
-deb $mirror $codename main contrib non-free
-deb-src $mirror $codename main contrib non-free
+deb {{mirror}} {{codename}} main contrib non-free
+deb-src {{mirror}} {{codename}} main contrib non-free

-\## Major bug fix updates produced after the final release of the
-\## distribution.
-deb $security $codename/updates main contrib non-free
-deb-src $security $codename/updates main contrib non-free
-deb $mirror $codename-updates main contrib non-free
-deb-src $mirror $codename-updates main contrib non-free
+## Major bug fix updates produced after the final release of the
+## distribution.
+deb {{security}} {{codename}}/updates main contrib non-free
+deb-src {{security}} {{codename}}/updates main contrib non-free
+deb {{mirror}} {{codename}}-updates main contrib non-free
+deb-src {{mirror}} {{codename}}-updates main contrib non-free

-\## Uncomment the following two lines to add software from the 'backports'
-\## repository.
-\## N.B. software from this repository may not have been tested as
-\## extensively as that contained in the main release, although it includes
-\## newer versions of some applications which may provide useful features.
-# deb http://backports.debian.org/debian-backports $codename-backports main contrib non-free
-# deb-src http://backports.debian.org/debian-backports $codename-backports main contrib non-free
+## Uncomment the following two lines to add software from the 'backports'
+## repository.
+## 
+## N.B. software from this repository may not have been tested as
+## extensively as that contained in the main release, although it includes
+## newer versions of some applications which may provide useful features.
+{#
+deb http://backports.debian.org/debian-backports {{codename}}-backports main contrib non-free
+deb-src http://backports.debian.org/debian-backports {{codename}}-backports main contrib non-free
+-#}
--- a/templates/sources.list.ubuntu.tmpl
+++ b/templates/sources.list.ubuntu.tmpl
@ -1,60 +1,60 @@
-\## Note, this file is written by cloud-init on first boot of an instance
-\## modifications made here will not survive a re-bundle.
-\## if you wish to make changes you can:
-\## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
-\##     or do the same in user-data
-\## b.) add sources in /etc/apt/sources.list.d
-\## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl
-\###
+## template:jinja
+## Note, this file is written by cloud-init on first boot of an instance
+## modifications made here will not survive a re-bundle.
+## if you wish to make changes you can:
+## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
+##     or do the same in user-data
+## b.) add sources in /etc/apt/sources.list.d
+## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl

 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
 # newer versions of the distribution.
-deb $mirror $codename main
-deb-src $mirror $codename main
+deb {{mirror}} {{codename}} main
+deb-src {{mirror}} {{codename}} main

-\## Major bug fix updates produced after the final release of the
-\## distribution.
-deb $mirror $codename-updates main
-deb-src $mirror $codename-updates main
+## Major bug fix updates produced after the final release of the
+## distribution.
+deb {{mirror}} {{codename}}-updates main
+deb-src {{mirror}} {{codename}}-updates main

-\## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
-\## team. Also, please note that software in universe WILL NOT receive any
-\## review or updates from the Ubuntu security team.
-deb $mirror $codename universe
-deb-src $mirror $codename universe
-deb $mirror $codename-updates universe
-deb-src $mirror $codename-updates universe
+## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
+## team. Also, please note that software in universe WILL NOT receive any
+## review or updates from the Ubuntu security team.
+deb {{mirror}} {{codename}} universe
+deb-src {{mirror}} {{codename}} universe
+deb {{mirror}} {{codename}}-updates universe
+deb-src {{mirror}} {{codename}}-updates universe

-\## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
-\## team, and may not be under a free licence. Please satisfy yourself as to
-\## your rights to use the software. Also, please note that software in 
-\## multiverse WILL NOT receive any review or updates from the Ubuntu
-\## security team.
-# deb $mirror $codename multiverse
-# deb-src $mirror $codename multiverse
-# deb $mirror $codename-updates multiverse
-# deb-src $mirror $codename-updates multiverse
+## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
+## team, and may not be under a free licence. Please satisfy yourself as to
+## your rights to use the software. Also, please note that software in 
+## multiverse WILL NOT receive any review or updates from the Ubuntu
+## security team.
+# deb {{mirror}} {{codename}} multiverse
+# deb-src {{mirror}} {{codename}} multiverse
+# deb {{mirror}} {{codename}}-updates multiverse
+# deb-src {{mirror}} {{codename}}-updates multiverse

-\## Uncomment the following two lines to add software from the 'backports'
-\## repository.
-\## N.B. software from this repository may not have been tested as
-\## extensively as that contained in the main release, although it includes
-\## newer versions of some applications which may provide useful features.
-\## Also, please note that software in backports WILL NOT receive any review
-\## or updates from the Ubuntu security team.
-# deb $mirror $codename-backports main restricted universe multiverse
-# deb-src $mirror $codename-backports main restricted universe multiverse
+## Uncomment the following two lines to add software from the 'backports'
+## repository.
+## N.B. software from this repository may not have been tested as
+## extensively as that contained in the main release, although it includes
+## newer versions of some applications which may provide useful features.
+## Also, please note that software in backports WILL NOT receive any review
+## or updates from the Ubuntu security team.
+# deb {{mirror}} {{codename}}-backports main restricted universe multiverse
+# deb-src {{mirror}} {{codename}}-backports main restricted universe multiverse

-\## Uncomment the following two lines to add software from Canonical's
-\## 'partner' repository.
-\## This software is not part of Ubuntu, but is offered by Canonical and the
-\## respective vendors as a service to Ubuntu users.
-# deb http://archive.canonical.com/ubuntu $codename partner
-# deb-src http://archive.canonical.com/ubuntu $codename partner
+## Uncomment the following two lines to add software from Canonical's
+## 'partner' repository.
+## This software is not part of Ubuntu, but is offered by Canonical and the
+## respective vendors as a service to Ubuntu users.
+# deb http://archive.canonical.com/ubuntu {{codename}} partner
+# deb-src http://archive.canonical.com/ubuntu {{codename}} partner

-deb $security $codename-security main
-deb-src $security $codename-security main
-deb $security $codename-security universe
-deb-src $security $codename-security universe
-# deb $security $codename-security multiverse
-# deb-src $security $codename-security multiverse
+deb {{security}} {{codename}}-security main
+deb-src {{security}} {{codename}}-security main
+deb {{security}} {{codename}}-security universe
+deb-src {{security}} {{codename}}-security universe
+# deb {{security}} {{codename}}-security multiverse
+# deb-src {{security}} {{codename}}-security multiverse
--- a/tests/unittests/test_templating.py
+++ b/tests/unittests/test_templating.py
@ -0,0 +1,107 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2014 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from tests.unittests import helpers as test_helpers
+import textwrap
+
+from cloudinit import templater
+
+
+class TestTemplates(test_helpers.TestCase):
+    def test_render_basic(self):
+        in_data = textwrap.dedent("""
+            ${b}
+
+            c = d
+            """)
+        in_data = in_data.strip()
+        expected_data = textwrap.dedent("""
+            2
+
+            c = d
+            """)
+        out_data = templater.basic_render(in_data, {'b': 2})
+        self.assertEqual(expected_data.strip(), out_data)
+
+    def test_detection(self):
+        blob = "## template:cheetah"
+
+        (template_type, renderer, contents) = templater.detect_template(blob)
+        self.assertIn("cheetah", template_type)
+        self.assertEqual("", contents.strip())
+
+        blob = "blahblah $blah"
+        (template_type, renderer, contents) = templater.detect_template(blob)
+        self.assertIn("cheetah", template_type)
+        self.assertEquals(blob, contents)
+
+        blob = '##template:something-new'
+        self.assertRaises(ValueError, templater.detect_template, blob)
+
+    def test_render_cheetah(self):
+        blob = '''## template:cheetah
+$a,$b'''
+        c = templater.render_string(blob, {"a": 1, "b": 2})
+        self.assertEquals("1,2", c)
+
+    def test_render_jinja(self):
+        blob = '''## template:jinja
+{{a}},{{b}}'''
+        c = templater.render_string(blob, {"a": 1, "b": 2})
+        self.assertEquals("1,2", c)
+
+    def test_render_default(self):
+        blob = '''$a,$b'''
+        c = templater.render_string(blob, {"a": 1, "b": 2})
+        self.assertEquals("1,2", c)
+
+    def test_render_basic_deeper(self):
+        hn = 'myfoohost.yahoo.com'
+        expected_data = "h=%s\nc=d\n" % hn
+        in_data = "h=$hostname.canonical_name\nc=d\n"
+        params = {
+            "hostname": {
+                "canonical_name": hn,
+            },
+        }
+        out_data = templater.render_string(in_data, params)
+        self.assertEqual(expected_data, out_data)
+
+    def test_render_basic_no_parens(self):
+        hn = "myfoohost"
+        in_data = "h=$hostname\nc=d\n"
+        expected_data = "h=%s\nc=d\n" % hn
+        out_data = templater.basic_render(in_data, {'hostname': hn})
+        self.assertEqual(expected_data, out_data)
+
+    def test_render_basic_parens(self):
+        hn = "myfoohost"
+        in_data = "h = ${hostname}\nc=d\n"
+        expected_data = "h = %s\nc=d\n" % hn
+        out_data = templater.basic_render(in_data, {'hostname': hn})
+        self.assertEqual(expected_data, out_data)
+
+    def test_render_basic2(self):
+        mirror = "mymirror"
+        codename = "zany"
+        in_data = "deb $mirror $codename-updates main contrib non-free"
+        ex_data = "deb %s %s-updates main contrib non-free" % (mirror, codename)
+
+        out_data = templater.basic_render(in_data,
+            {'mirror': mirror, 'codename': codename})
+        self.assertEqual(ex_data, out_data)