summaryrefslogtreecommitdiff
path: root/cloudinit/templater.py
diff options
context:
space:
mode:
authorJoshua Harlow <harlowja@yahoo-inc.com>2014-07-16 11:31:31 -0700
committerJoshua Harlow <harlowja@yahoo-inc.com>2014-07-16 11:31:31 -0700
commit7dfabbefbadf626503bed8fe4c6e79243bde73ce (patch)
tree40e008ed320d47d2dc4af7127ba0e39ccfa58d1a /cloudinit/templater.py
parentb740568ddfe6194af7c2c5d7123b3cc2a07fa7f7 (diff)
downloadvyos-cloud-init-7dfabbefbadf626503bed8fe4c6e79243bde73ce.tar.gz
vyos-cloud-init-7dfabbefbadf626503bed8fe4c6e79243bde73ce.zip
Add basic renderer support and more robust import handling
Diffstat (limited to 'cloudinit/templater.py')
-rw-r--r--cloudinit/templater.py107
1 files changed, 81 insertions, 26 deletions
diff --git a/cloudinit/templater.py b/cloudinit/templater.py
index 9922c633..459f241a 100644
--- a/cloudinit/templater.py
+++ b/cloudinit/templater.py
@@ -20,30 +20,72 @@
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import collections
import re
-from Cheetah.Template import Template as CTemplate
+try:
+ from Cheetah.Template import Template as CTemplate
+ CHEETAH_AVAILABLE = True
+except (ImportError, AttributeError):
+ CHEETAH_AVAILABLE = False
-import jinja2
-from jinja2 import Template as JTemplate
+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__)
-DEF_RENDERER = 'cheetah'
-RENDERERS = {
- 'jinja': (lambda content, params:
- JTemplate(content,
- undefined=jinja2.StrictUndefined,
- trim_blocks=True).render(**params)),
- 'cheetah': (lambda content, params:
- CTemplate(content, searchList=[params]).respond()),
-}
TYPE_MATCHER = re.compile(r"##\s*template:(.*)", re.I)
+BASIC_MATCHER = re.compile(r'\$\{([A-Za-z0-9_.]+)\}')
+
+
+def basic_render(content, params):
+ """This does simple replacement of bash variable like templates.
+
+ It identifies patterns like ${a} and can also identify patterns like
+ ${a.b} which will look for a key 'b' in the dictionary rooted by key 'a'.
+ """
+
+ def replacer(match):
+ path = collections.deque(match.group(1).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:
@@ -51,14 +93,32 @@ def detect_template(text):
rest = ''
type_match = TYPE_MATCHER.match(ident)
if not type_match:
- return (DEF_RENDERER, text)
- template_type = type_match.group(1).lower().strip()
- if template_type not in RENDERERS:
- raise ValueError("Unknown template type '%s' requested"
- % template_type)
+ 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:
- return (template_type, rest)
-
+ 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)
@@ -72,10 +132,5 @@ def render_to_file(fn, outfn, params, mode=0644):
def render_string(content, params):
if not params:
params = {}
- try:
- renderer, content = detect_template(content)
- except ValueError as e:
- renderer = DEF_RENDERER
- LOG.warn("%s, using renderer %s", e, renderer)
- LOG.debug("Rendering %s using renderer '%s'", content, renderer)
- return RENDERERS[renderer](content, params)
+ template_type, renderer, content = detect_template(content)
+ return renderer(content, params)