Added sysfs state module to manage kernel objects

changelog/60154.added

@@ -0,0 +1 @@
+State module to manage SysFS attributes

doc/ref/states/all/index.rst

@@ -303,6 +303,7 @@ state modules
     supervisord
     svn
     sysctl
+    sysfs
     syslog_ng
     sysrc
     telemetry_alert

doc/ref/states/all/salt.states.sysfs.rst

@@ -0,0 +1,5 @@
+salt.states.sysfs
+==================
+
+.. automodule:: salt.states.sysfs
+    :members:

salt/states/sysfs.py

@@ -0,0 +1,73 @@
+"""
+Configuration of the kernel using sysfs
+=======================================
+
+Control the kernel object attributes exported by sysfs
+
+.. code-block:: yaml
+
+  kernel/mm/transparent_hugepage/enabled
+    sysfs.present:
+      - value: never
+
+.. versionadded: TBD
+"""
+
+import re
+
+
+def __virtual__():
+    """
+    This state is only available on Minions which support sysctl
+    """
+    if "sysfs.attr" in __salt__:
+        return True
+    return (False, "sysfs module could not be loaded")
+
+
+def present(name, value, config=None):
+    """
+    Ensure that the named sysfs attribute is set with the defined value
+
+    name
+        The name of the sysfs attribute to edit
+
+    value
+        The sysfs value to apply
+
+    """
+    ret = {"name": name, "result": True, "changes": {}, "comment": ""}
+
+    current = __salt__["sysfs.read"](name)
+    if current is False:
+        ret["result"] = False
+        ret["comment"] = "SysFS attribute {} doesn't exist.".format(name)
+    else:
+        # if the return is a dict, the "name" is an object not an attribute
+        if isinstance(current, dict):
+            ret["result"] = False
+            ret["comment"] = "{} is not a SysFS attribute.".format(name)
+        else:
+            # some attribute files lists all available options and the selected one between []
+            if isinstance(current, str):
+                current = re.sub(r"(.*\[|\].*)", "", current)
+            if value == current:
+                ret["result"] = True
+                ret["comment"] = "SysFS attribute {} is already set.".format(name)
+            else:
+                ret["result"] = None
+
+    if ret["result"] is None:
+        if __opts__["test"]:
+            ret["comment"] = "SysFS attribute {} set to be changed.".format(name)
+        else:
+            update = __salt__["sysfs.write"](name, value)
+            if not update:
+                ret["result"] = False
+                ret["comment"] = "Failed to set {} to {}".format(name, value)
+            else:
+                ret["result"] = True
+                ret["changes"] = {name: value}
+                ret["comment"] = "Updated SysFS attribute {} to {}".format(name, value)
+
+    return ret

tests/pytests/unit/states/test_sysfs.py

@@ -0,0 +1,117 @@
+"""
+    :codeauthor: Piter Punk <piterpunk@slackware.com>
+"""
+
+import pytest
+import salt.states.sysfs as sysfs
+from tests.support.mock import MagicMock, patch
+
+
+@pytest.fixture
+def configure_loader_modules():
+    return {sysfs: {}}
+
+
+def test_if_the_sysfs_attribute_exists():
+    """
+    Test sysfs.present for a non-existent attribute
+    """
+    name = "block/sda/queue/this_does_not_exist"
+    value = "none"
+    comment = "SysFS attribute {} doesn't exist.".format(name)
+    ret = {"name": name, "result": False, "changes": {}, "comment": comment}
+
+    mock_read = MagicMock(return_value=False)
+    with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+        assert sysfs.present(name, value) == ret
+
+
+def test_name_is_an_object_and_not_an_attribute():
+    """
+    Test sysfs.present targeting an object and not one of its attributes
+    """
+    name = "block/sda/queue"
+    value = "none"
+    comment = "{} is not a SysFS attribute.".format(name)
+    ret = {"name": name, "result": False, "changes": {}, "comment": comment}
+
+    read_from_sysfs = {
+        "rotational": 1,
+        "rq_affinity": 1,
+        "scheduler": "[none] mq-deadline",
+    }
+
+    mock_read = MagicMock(return_value=read_from_sysfs)
+    with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+        assert sysfs.present(name, value) == ret
+
+
+def test_already_set():
+    """
+    Test sysfs.present with equal old and new values
+    """
+    name = "block/sda/queue"
+    value = "none"
+    comment = "SysFS attribute {} is already set.".format(name)
+    ret = {"name": name, "result": True, "changes": {}, "comment": comment}
+
+    read_from_sysfs = "[none] mq-deadline"
+
+    mock_read = MagicMock(return_value=read_from_sysfs)
+    with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+        assert sysfs.present(name, value) == ret
+
+
+def test_set_new_value_with_test_equals_true():
+    """
+    Test sysfs.present setting a new value
+    """
+    name = "devices/system/cpu/cpufreq/policy0"
+    value = "powersave"
+    comment = "SysFS attribute {} set to be changed.".format(name)
+    ret = {"name": name, "result": None, "changes": {}, "comment": comment}
+
+    read_from_sysfs = "performance"
+
+    mock_read = MagicMock(return_value=read_from_sysfs)
+    with patch.dict(sysfs.__opts__, {"test": True}):
+        with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+            assert sysfs.present(name, value) == ret
+
+
+def test_set_new_value_with_success():
+    """
+    Test sysfs.present setting a new value
+    """
+    name = "block/sda/queue/scheduler"
+    value = "mq-deadline"
+    comment = "Updated SysFS attribute {} to {}".format(name, value)
+    ret = {"name": name, "result": True, "changes": {name: value}, "comment": comment}
+
+    read_from_sysfs = "[none] mq-deadline"
+
+    mock_read = MagicMock(return_value=read_from_sysfs)
+    with patch.dict(sysfs.__opts__, {"test": False}):
+        with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+            mock_write = MagicMock(return_value=True)
+            with patch.dict(sysfs.__salt__, {"sysfs.write": mock_write}):
+                assert sysfs.present(name, value) == ret
+
+
+def test_set_new_value_with_failure():
+    """
+    Test sysfs.present failure writing the value
+    """
+    name = "block/sda/queue/scheduler"
+    value = "imaginary_scheduler"
+    comment = "Failed to set {} to {}".format(name, value)
+    ret = {"name": name, "result": False, "changes": {}, "comment": comment}
+
+    read_from_sysfs = "[none] mq-deadline"
+
+    mock_read = MagicMock(return_value=read_from_sysfs)
+    with patch.dict(sysfs.__opts__, {"test": False}):
+        with patch.dict(sysfs.__salt__, {"sysfs.read": mock_read}):
+            mock_write = MagicMock(return_value=False)
+            with patch.dict(sysfs.__salt__, {"sysfs.write": mock_write}):
+                assert sysfs.present(name, value) == ret