cephadm: expand the templating module

Expand the templating module so that templates can be source from the
python package. Add (more) convenient to use methods.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

diff --git a/src/cephadm/cephadmlib/templating.py b/src/cephadm/cephadmlib/templating.py
index 29e0f825288d7119a4749973b8f90e8da70e7bd0..ceb2f6fbddf370317e365dfe5c1324f6c3cdf609 100644 (file)
--- a/src/cephadm/cephadmlib/templating.py
+++ b/src/cephadm/cephadmlib/templating.py
@@ -1,20 +1,61 @@
 # templating.py - functions to wrap string/file templating libs
 
 
-from typing import Any
+from typing import Any, Optional, IO
 
 import jinja2
 
 from .context import CephadmContext
 
+_PKG = __name__.rsplit('.', 1)[0]
+_DIR = 'templates'
 
-def template_str(ctx: CephadmContext, template: str, **kwargs: Any) -> str:
-    loader = jinja2.BaseLoader()
-    return (
-        jinja2.Environment(loader=loader)
-        .from_string(template)
-        .render(
-            ctx=ctx,
-            **kwargs,
-        )
-    )
+
+class Templater:
+    """Cephadm's generic templater class. Based on jinja2."""
+
+    # defaults that can be overridden for testing purposes
+    # and are lazily acquired
+    _jinja2_loader: Optional[jinja2.BaseLoader] = None
+    _jinja2_env: Optional[jinja2.Environment] = None
+    _pkg = _PKG
+    _dir = _DIR
+
+    @property
+    def _env(self) -> jinja2.Environment:
+        if self._jinja2_env is None:
+            self._jinja2_env = jinja2.Environment(loader=self._loader)
+        return self._jinja2_env
+
+    @property
+    def _loader(self) -> jinja2.BaseLoader:
+        if self._jinja2_loader is None:
+            self._jinja2_loader = jinja2.PackageLoader(self._pkg, self._dir)
+        return self._jinja2_loader
+
+    def render_str(
+        self, ctx: CephadmContext, template: str, **kwargs: Any
+    ) -> str:
+        return self._env.from_string(template).render(ctx=ctx, **kwargs)
+
+    def render(self, ctx: CephadmContext, name: str, **kwargs: Any) -> str:
+        return self._env.get_template(name).render(ctx=ctx, **kwargs)
+
+    def render_to_file(
+        self, fp: IO, ctx: CephadmContext, name: str, **kwargs: Any
+    ) -> None:
+        self._env.get_template(name).stream(ctx=ctx, **kwargs).dump(fp)
+
+
+# create a defaultTemplater instace from the Templater class that will
+# be used to provide a simple set of methods
+defaultTemplater = Templater()
+
+# (temporary alias) template_str is currently used by the cephadm code
+template_str = defaultTemplater.render_str
+
+# alias methods as module level functions for convenience. most callers do
+# not need to care that these are implemented via a class
+render_str = defaultTemplater.render_str
+render = defaultTemplater.render
+render_to_file = defaultTemplater.render_to_file