hotsos/core: add name aliasing support

at the moment, scenarios are using the long import paths in order to
reference to a Python property. this feature allows assigning an alias
to a Python class or variable in order to make using plugin property
interfaces easier.

Added aliases to the plugins.
Updated existing scenarios to use aliases.

Fixes canonical#912

Signed-off-by: Mustafa Kemal Gilor <[email protected]>

hotsos/core/alias.py

@@ -0,0 +1,82 @@
+"""Aliasing utilities."""
+
+from hotsos.core.log import log
+
+
+class AliasAlreadyInUseError(Exception):
+    def __init__(self, name):
+        self.message = f"Alias '{name}` already in use!"
+
+    def __str__(self):
+        return self.message
+
+
+class AliasRegistry:
+    """
+    A class that provides a registry for aliasing Python things.
+    """
+
+    # A class-level dictionary to store registered aliases.
+    registry = {}
+
+    @staticmethod
+    def register(name, decoratee):
+        """
+        Register a function, method, or property under an alias.
+
+        This method handles different types of Python objects and creates
+        appropriate wrappers or registrations based on the object type.
+
+        Args:
+            name (str): The alias under which to register the decoratee.
+            decoratee (callable or property): The Python object to be
+            registered.
+
+        Raises:
+            AliasAlreadyInUseError: If the alias name is already registered.
+        """
+        isprop = isinstance(decoratee, property)
+        target = decoratee.fget if isprop else decoratee
+
+        if name in AliasRegistry.registry:
+            raise AliasAlreadyInUseError(name)
+
+        import_path = f"{target.__module__}.{target.__qualname__}"
+        log.debug("registering alias `%s` --> {%s}", name, import_path)
+        # Register full import path.
+        AliasRegistry.registry[name] = import_path
+
+    @staticmethod
+    def resolve(the_alias):
+        """
+        Retrieve a registered alias.
+
+        Args:
+            the_alias (str): The alias to retrieve.
+
+        Returns:
+            callable: The function or wrapper associated with the alias.
+
+        Raises:
+            NoSuchAliasError: No such alias in the registry.
+        """
+
+        if the_alias not in AliasRegistry.registry:
+            return None
+
+        value = AliasRegistry.registry[the_alias]
+        log.debug("alias %s resolved to %s", the_alias, value)
+        return value
+
+
+def alias(argument):
+    """Create an alias for a property, function or a thing."""
+
+    def real_decorator(func):
+        """We're not wrapping the func as we don't want
+        to do anything at runtime. We just want to alias
+        `func` to some user-defined name and call it on-demand."""
+        AliasRegistry.register(argument, func)
+        return func
+
+    return real_decorator

hotsos/core/host_helpers/filestat.py

@@ -3,6 +3,7 @@
 from hotsos.core.config import HotSOSConfig
 from hotsos.core.factory import FactoryBase
 from hotsos.core.log import log
+from hotsos.core.alias import alias
 
 
 class FileObj():
@@ -38,6 +39,7 @@ def size(self):
         return size
 
 
+@alias("file")
 class FileFactory(FactoryBase):
     """
     Factory to dynamically create FileObj objects using file path as input.

hotsos/core/host_helpers/ssl.py

@@ -7,6 +7,7 @@
 from hotsos.core.factory import FactoryBase
 from hotsos.core.host_helpers.cli import CLIHelper
 from hotsos.core.log import log
+from hotsos.core.alias import alias
 
 
 class SSLCertificate():
@@ -65,6 +66,7 @@ def certificate_expires_soon(self):
         return self.certificate.days_to_expire <= self.expire_days
 
 
+@alias('sslcert')
 class SSLCertificatesFactory(FactoryBase):
     """
     Factory to dynamically create SSLCertificate objects for given paths.

hotsos/core/plugins/juju/common.py

@@ -3,6 +3,7 @@
 from hotsos.core.host_helpers import PebbleHelper, SystemdHelper
 from hotsos.core.plugins.juju.resources import JujuBase
 from hotsos.core import plugintools
+from hotsos.core.alias import alias
 
 SVC_VALID_SUFFIX = r'[0-9a-zA-Z-_]*'
 JUJU_SVC_EXPRS = [r'mongod{}'.format(SVC_VALID_SUFFIX),
@@ -12,6 +13,7 @@
                   r'(?:^|[^\s])juju-db{}'.format(SVC_VALID_SUFFIX)]
 
 
+@alias('juju')
 class JujuChecksBase(plugintools.PluginPartBase, JujuBase):
     plugin_name = 'juju'
     plugin_root_index = 12

hotsos/core/plugins/juju/resources.py

@@ -9,6 +9,7 @@
 from hotsos.core.config import HotSOSConfig
 from hotsos.core.log import log
 from hotsos.core import utils
+from hotsos.core.alias import alias
 
 
 class JujuMachine():
@@ -174,6 +175,7 @@ def __init__(self, name, version):
         self.version = int(version)
 
 
+@alias('juju.base')
 class JujuBase():
     CHARM_MANIFEST_GLOB = "agents/unit-*/state/deployer/manifests"
 

hotsos/core/plugins/kernel/common.py

@@ -5,8 +5,10 @@
 from hotsos.core import host_helpers, plugintools
 from hotsos.core.config import HotSOSConfig
 from hotsos.core.plugins.kernel.config import KernelConfig
+from hotsos.core.alias import alias
 
 
+@alias('kernel')
 class KernelBase():
 
     @cached_property

hotsos/core/plugins/kernel/config.py

@@ -3,6 +3,7 @@
 
 from hotsos.core.config import HotSOSConfig
 from hotsos.core import host_helpers
+from hotsos.core.alias import alias
 
 
 class KernelConfig(host_helpers.ConfigBase):
@@ -39,6 +40,7 @@ def _load(self):
                     break
 
 
+@alias('kernel.systemdconfig')
 class SystemdConfig(host_helpers.IniConfigBase):
     """Systemd configuration."""
 

hotsos/core/plugins/kernel/kernlog/calltrace.py

@@ -12,6 +12,7 @@
     TraceTypeBase,
     KernLogBase,
 )
+from hotsos.core.alias import alias
 
 KERNLOG_TS = r'\[\s*\d+\.\d+\]'
 KERNLOG_PREFIX = (r'(?:\S+\s+\d+\s+[\d:]+\s+\S+\s+\S+:\s+)?{}'.
@@ -454,6 +455,7 @@ def __iter__(self):
         yield from self.hungtasks
 
 
+@alias("kernel.calltrace")
 class CallTraceManager(KernLogBase):
 
     def __init__(self, *args, **kwargs):

hotsos/core/plugins/kernel/kernlog/events.py

@@ -1,6 +1,7 @@
 from hotsos.core.log import log
 from hotsos.core.plugins.kernel.kernlog.common import KernLogBase
 from hotsos.core.search import SearchDef
+from hotsos.core.alias import alias
 
 
 class OverMTUDroppedPacketEvent():
@@ -11,6 +12,7 @@ def searchdef(self):
                          hint='dropped', tag='over-mtu-dropped')
 
 
+@alias('kernel.kernlog.events')
 class KernLogEvents(KernLogBase):
 
     def __init__(self, *args, **kwargs):

hotsos/core/plugins/kernel/memory.py

@@ -3,6 +3,7 @@
 
 from hotsos.core.config import HotSOSConfig
 from hotsos.core.utils import sorted_dict
+from hotsos.core.alias import alias
 
 
 class _BaseProcKeyValue():
@@ -50,6 +51,7 @@ def __getattr__(self, key):
                              format(key, self.__class__.__name__))
 
 
+@alias('kernel.vmstat')
 class VMStat(_BaseProcKeyValue):
     VALID_KEYS = ['compact_fail', 'compact_success']
 
@@ -58,6 +60,7 @@ def path(self):
         return os.path.join(HotSOSConfig.data_root, 'proc/vmstat')
 
     @property
+    @alias("kernel.vmstat.compaction_failures_pct")
     def compaction_failures_percent(self):
         if not os.path.exists(self.path):
             return 0
@@ -70,6 +73,7 @@ def compaction_failures_percent(self):
         return int(fail_count / (success_count / 100))
 
 
+@alias("kernel.meminfo")
 class MemInfo(_BaseProcKeyValue):
     VALID_KEYS = ['MemTotal', 'MemAvailable', 'Hugetlb', 'HugePages_Total',
                   'HugePages_Free']
@@ -111,6 +115,7 @@ def hugep_used_to_hugep_total_percentage(self):
         return round(100 - (self.HugePages_Free * 100) / self.HugePages_Total)
 
 
+@alias("kernel.slab")
 class SlabInfo():
 
     def __init__(self, filter_names=None):
@@ -284,6 +289,7 @@ def high_order_seq(self):
         return count
 
 
+@alias('kernel.memchecks')
 class MemoryChecks():
 
     @property

hotsos/core/plugins/kernel/net.py

@@ -6,6 +6,7 @@
 from hotsos.core.host_helpers import SYSCtlFactory, CLIHelperFile
 from hotsos.core.log import log
 from hotsos.core.search import FileSearcher, SearchDef, ResultFieldInfo
+from hotsos.core.alias import alias
 
 
 class ProcNetBase(abc.ABC):
@@ -109,6 +110,7 @@ def __init__(self):
                                         'proc/net/snmp'))
 
 
+@alias('kernel.net.snmp.tcp')
 class SNMPTcp(SNMPBase):
 
     def _percent_in_segs(self, field):
@@ -154,6 +156,7 @@ def __getattr__(self, fld):
         return super().__getattr__(fld)
 
 
+@alias('kernel.net.snmp.udp')
 class SNMPUdp(SNMPBase):
 
     @property
@@ -208,6 +211,7 @@ def __init__(self):
         self.net_snmp_tcp = SNMPTcp()
 
 
+@alias('kernel.net.netstat.tcp')
 class NetStatTCP(NetStatBase):
 
     @property
@@ -286,6 +290,7 @@ def __getattr__(self, fld):
         return super().__getattr__(fld)
 
 
+@alias('kernel.net.sockstat')
 class SockStat(ProcNetBase):
 
     """
@@ -534,6 +539,7 @@ def all_with_inode(self, inode):
         return list(filter(lambda x: (x.NODE == inode), self.data))
 
 
+@alias('kernel.net.netlink')
 class NetLink(STOVParserBase):
     """
     Provides a way to extract fields from /proc/net/netlink.

hotsos/core/plugins/kernel/sysfs.py

@@ -4,6 +4,7 @@
 from hotsos.core.config import HotSOSConfig
 from hotsos.core import host_helpers
 from hotsos.core.plugins.system.system import SystemBase
+from hotsos.core.alias import alias
 
 
 class SYSFSBase():
@@ -23,6 +24,7 @@ def get(relpath):
             return fd.read().strip()
 
 
+@alias('kernel.sysfs.cpu')
 class CPU(SYSFSBase):
 
     @property

hotsos/core/plugins/lxd/common.py

@@ -11,13 +11,14 @@
     FileSearcher, SearchDef,
     SequenceSearchDef
 )
-
+from hotsos.core.alias import alias
 
 CORE_APT = ['lxd', 'lxc']
 CORE_SNAPS = [r"(?:snap\.)?{}".format(p) for p in CORE_APT]
 SERVICE_EXPRS = [r"{}\S*".format(s) for s in CORE_SNAPS]
 
 
+@alias('lxd')
 class LXD():
 
     @cached_property

hotsos/core/plugins/mysql.py

@@ -11,12 +11,14 @@
     host_helpers,
     plugintools,
 )
+from hotsos.core.alias import alias
 
 SVC_VALID_SUFFIX = r'[0-9a-zA-Z-_]*'
 MYSQL_SVC_EXPRS = [r'mysql{}'.format(SVC_VALID_SUFFIX)]
 CORE_APT = ['mysql']
 
 
+@alias('mysql')
 class MySQLChecksBase(plugintools.PluginPartBase):
     plugin_name = 'mysql'
     plugin_root_index = 3

hotsos/core/plugins/openstack/common.py

@@ -26,8 +26,10 @@
 from hotsos.core.plugins.openstack.octavia import OctaviaBase
 from hotsos.core import plugintools
 from hotsos.core.ycheck.events import EventHandlerBase, EventCallbackBase
+from hotsos.core.alias import alias
 
 
+@alias('openstack')
 class OpenstackBase():
 
     def __init__(self, *args, **kwargs):
@@ -239,6 +241,7 @@ def apache2_allow_encoded_slashes_on(self):
         return False
 
 
+@alias('openstack.checks')
 class OpenstackChecksBase(OpenstackBase, plugintools.PluginPartBase):
     plugin_name = "openstack"
     plugin_root_index = 4

hotsos/core/plugins/openstack/neutron.py

@@ -9,6 +9,7 @@
     OpenstackConfig,
     OSTServiceBase,
 )
+from hotsos.core.alias import alias
 
 # See https://github.com/openstack/neutron-lib/blob/master/neutron_lib/constants.py#L346  # noqa, pylint: disable=C0301
 IP_HEADER_BYTES = 20
@@ -44,6 +45,7 @@ def bind_interfaces(self):
         return interfaces
 
 
+@alias('neutron.service_checks')
 class ServiceChecks():
 
     @cached_property
@@ -128,6 +130,7 @@ def find_router_with_vr_id(self, vr_id):
         return None
 
 
+@alias('neutron.config')
 class Config(FactoryBase):
 
     def __getattr__(self, path):