1 files changed, 109 insertions, 0 deletions
diff --git a/src/pybind/mgr/cephadm/template.py b/src/pybind/mgr/cephadm/template.py
new file mode 100644
index 000000000..0d62e587c
--- /dev/null
+++ b/src/pybind/mgr/cephadm/template.py
@@ -0,0 +1,109 @@
+import copy
+from typing import Optional, TYPE_CHECKING
+
+from jinja2 import Environment, PackageLoader, select_autoescape, StrictUndefined
+from jinja2 import exceptions as j2_exceptions
+
+if TYPE_CHECKING:
+    from cephadm.module import CephadmOrchestrator
+
+
+class TemplateError(Exception):
+    pass
+
+
+class UndefinedError(TemplateError):
+    pass
+
+
+class TemplateNotFoundError(TemplateError):
+    pass
+
+
+class TemplateEngine:
+    def render(self, name: str, context: Optional[dict] = None) -> str:
+        raise NotImplementedError()
+
+
+class Jinja2Engine(TemplateEngine):
+    def __init__(self) -> None:
+        self.env = Environment(
+            loader=PackageLoader('cephadm', 'templates'),
+            autoescape=select_autoescape(['html', 'xml'], default_for_string=False),
+            trim_blocks=True,
+            lstrip_blocks=True,
+            undefined=StrictUndefined
+        )
+
+    def render(self, name: str, context: Optional[dict] = None) -> str:
+        try:
+            template = self.env.get_template(name)
+            if context is None:
+                return template.render()
+            return template.render(context)
+        except j2_exceptions.UndefinedError as e:
+            raise UndefinedError(e.message)
+        except j2_exceptions.TemplateNotFound as e:
+            raise TemplateNotFoundError(e.message)
+
+    def render_plain(self, source: str, context: Optional[dict]) -> str:
+        try:
+            template = self.env.from_string(source)
+            if context is None:
+                return template.render()
+            return template.render(context)
+        except j2_exceptions.UndefinedError as e:
+            raise UndefinedError(e.message)
+        except j2_exceptions.TemplateNotFound as e:
+            raise TemplateNotFoundError(e.message)
+
+
+class TemplateMgr:
+    def __init__(self, mgr: "CephadmOrchestrator"):
+        self.engine = Jinja2Engine()
+        self.base_context = {
+            'cephadm_managed': 'This file is generated by cephadm.'
+        }
+        self.mgr = mgr
+
+    def render(self, name: str,
+               context: Optional[dict] = None,
+               managed_context: bool = True,
+               host: Optional[str] = None) -> str:
+        """Render a string from a template with context.
+
+        :param name: template name. e.g. services/nfs/ganesha.conf.j2
+        :type name: str
+        :param context: a dictionary that contains values to be used in the template, defaults
+            to None
+        :type context: Optional[dict], optional
+        :param managed_context: to inject default context like managed header or not, defaults
+            to True
+        :type managed_context: bool, optional
+        :param host: The host name used to build the key to access
+            the module's persistent key-value store.
+        :type host: Optional[str], optional
+        :return: the templated string
+        :rtype: str
+        """
+        ctx = {}
+        if managed_context:
+            ctx = copy.deepcopy(self.base_context)
+        if context is not None:
+            ctx = {**ctx, **context}
+
+        # Check if the given name exists in the module's persistent
+        # key-value store, e.g.
+        # - blink_device_light_cmd
+        # - <host>/blink_device_light_cmd
+        # - services/nfs/ganesha.conf
+        store_name = name.rstrip('.j2')
+        custom_template = self.mgr.get_store(store_name, None)
+        if host and custom_template is None:
+            store_name = '{}/{}'.format(host, store_name)
+            custom_template = self.mgr.get_store(store_name, None)
+
+        if custom_template:
+            return self.engine.render_plain(custom_template, ctx)
+        else:
+            return self.engine.render(name, ctx)