feat: add util.mako_renderer() function

docs/narr/usage.rst

@@ -52,12 +52,15 @@ merely a personal convention.  You can define tasks however you need::
    """
 
    from fabric import task
-   from wuttamess import apt, sync
+   from wuttamess import apt, sync, util
 
 
    # nb. this is used below, for file sync
    root = sync.make_root('files')
 
+   # nb. this is for global mako template context etc.
+   env = {'machine_is_live': False}
+
 
    @task
    def bootstrap_all(c):
@@ -74,11 +77,13 @@ merely a personal convention.  You can define tasks however you need::
        """
        Bootstrap the base system
        """
+       renderers = {'mako': util.mako_renderer(c, env)}
+
        apt.dist_upgrade(c)
 
        # postfix
        apt.install(c, 'postfix')
-       if sync.check_isync(c, root, 'etc/postfix'):
+       if sync.check_isync(c, root, 'etc/postfix', renderers=renderers):
            c.run('systemctl restart postfix')
 
 

pyproject.toml

@@ -31,6 +31,8 @@ requires-python = ">= 3.8"
 dependencies = [
         "fabric",
         "fabsync",
+        "mako",
+        "typing_extensions",
 ]
 
 

src/wuttamess/util.py

@@ -24,9 +24,46 @@
 Misc. Utilities
 """
 
+from pathlib import Path
+from typing_extensions import Any, Mapping
+
+from mako.template import Template
+
 
 def exists(c, path):
     """
     Returns ``True`` if given path exists on the host, otherwise ``False``.
     """
     return not c.run(f'test -e {path}', warn=True).failed
+
+
+def mako_renderer(c, env={}):
+    """
+    This returns a *function* suitable for use as a ``fabsync`` file
+    renderer.  The function assumes the file is a Mako template.
+
+    :param c: Fabric connection.
+
+    :param env: Environment dictionary to be used as Mako template
+       context.
+
+    Typical usage is something like::
+
+       from fabric import task
+       from wuttamess import sync, util
+
+       root = sync.make_root('files')
+       env = {}
+
+       @task
+       def foo(c):
+
+           # define possible renderers for fabsync
+           renderers = {'mako': util.mako_renderer(c, env)}
+
+           sync.check_isync(c, root, 'etc/postfix', renderers=renderers)
+    """
+    def render(path: Path, vars: Mapping[str, Any], **kwargs) -> bytes:
+        return Template(filename=str(path)).render(**env)
+
+    return render

tests/files/bar/_sync.toml

@@ -0,0 +1,4 @@
+
+[files."baz"]
+renderer = 'mako'
+tags = ['baz']

tests/files/bar/baz

@@ -0,0 +1 @@
+machine_is_live = ${machine_is_live}

tests/test_util.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8; -*-
 
+import os
 from unittest import TestCase
 from unittest.mock import MagicMock
 
@@ -12,3 +13,14 @@ class TestExists(TestCase):
         c = MagicMock()
         mod.exists(c, '/foo')
         c.run.assert_called_once_with('test -e /foo', warn=True)
+
+
+class TestMakoRenderer(TestCase):
+
+    def test_basic(self):
+        c = MagicMock()
+        renderer = mod.mako_renderer(c, env={'machine_is_live': True})
+        here = os.path.dirname(__file__)
+        path = os.path.join(here, 'files', 'bar', 'baz')
+        rendered = renderer(path, vars={})
+        self.assertEqual(rendered, 'machine_is_live = True')