feat: add is_symlink() and set_timezone() util functions

src/wuttamess/util.py

@@ -37,6 +37,22 @@ def exists(c, path):
     return not c.run(f'test -e {path}', warn=True).failed
 
 
+def is_symlink(c, path):
+    """
+    Check if the given path is a symlink.
+
+    :param c: Fabric connection.
+
+    :param path: Path to check, on target machine.
+
+    :returns: ``True`` if path is a symlink, else ``False``.
+    """
+    # nb. this function is derived from one copied from fabric v1
+    cmd = 'test -L "$(echo %s)"' % path
+    result = c.run(cmd, warn=True)
+    return False if result.failed else True
+
+
 def mako_renderer(c, env={}):
     """
     This returns a *function* suitable for use as a ``fabsync`` file
@@ -67,3 +83,20 @@ def mako_renderer(c, env={}):
         return Template(filename=str(path)).render(**env)
 
     return render
+
+
+def set_timezone(c, timezone):
+    """
+    Set the system timezone.
+
+    :param c: Fabric connection.
+
+    :param timezone: Standard timezone name,
+       e.g. ``'America/Chicago'``.
+    """
+    c.run(f"bash -c 'echo {timezone} > /etc/timezone'")
+
+    if is_symlink(c, '/etc/localtime'):
+        c.run(f'ln -sf /usr/share/zoneinfo/{timezone} /etc/localtime')
+    else:
+        c.run(f'cp /usr/share/zoneinfo/{timezone} /etc/localtime')

tests/test_util.py

@@ -2,7 +2,7 @@
 
 import os
 from unittest import TestCase
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch, call
 
 from wuttamess import util as mod
 
@@ -15,6 +15,21 @@ class TestExists(TestCase):
         c.run.assert_called_once_with('test -e /foo', warn=True)
 
 
+class TestIsSymlink(TestCase):
+
+    def test_yes(self):
+        c = MagicMock()
+        c.run.return_value.failed = False
+        self.assertTrue(mod.is_symlink(c, '/foo'))
+        c.run.assert_called_once_with('test -L "$(echo /foo)"', warn=True)
+
+    def test_no(self):
+        c = MagicMock()
+        c.run.return_value.failed = True
+        self.assertFalse(mod.is_symlink(c, '/foo'))
+        c.run.assert_called_once_with('test -L "$(echo /foo)"', warn=True)
+
+
 class TestMakoRenderer(TestCase):
 
     def test_basic(self):
@@ -24,3 +39,26 @@ class TestMakoRenderer(TestCase):
         path = os.path.join(here, 'files', 'bar', 'baz')
         rendered = renderer(path, vars={})
         self.assertEqual(rendered, 'machine_is_live = True')
+
+
+class TestSetTimezone(TestCase):
+
+    def test_symlink(self):
+        c = MagicMock()
+        with patch.object(mod, 'is_symlink') as is_symlink:
+            is_symlink.return_value = True
+            mod.set_timezone(c, 'America/Chicago')
+            c.run.assert_has_calls([
+                call("bash -c 'echo America/Chicago > /etc/timezone'"),
+            ])
+            c.run.assert_called_with('ln -sf /usr/share/zoneinfo/America/Chicago /etc/localtime')
+
+    def test_not_symlink(self):
+        c = MagicMock()
+        with patch.object(mod, 'is_symlink') as is_symlink:
+            is_symlink.return_value = False
+            mod.set_timezone(c, 'America/Chicago')
+            c.run.assert_has_calls([
+                call("bash -c 'echo America/Chicago > /etc/timezone'"),
+            ])
+            c.run.assert_called_with('cp /usr/share/zoneinfo/America/Chicago /etc/localtime')