Revert "Remove layering violation in utils"

This reverts commit 0359a8f.

cmk/base/automations/check_mk.py

@@ -58,7 +58,6 @@
 from cmk.base.core_factory import create_core
 from cmk.base.diagnostics import DiagnosticsDump
 from cmk.base.discovered_labels import DiscoveredHostLabels, DiscoveredServiceLabels, ServiceLabel
-from cmk.fetchers import factory  # pylint: disable=cmk-module-layer-violation
 
 HistoryFile = str
 HistoryFilePair = Tuple[HistoryFile, HistoryFile]
@@ -1401,7 +1400,6 @@ def _execute_snmp(
             snmp_config,
             "",
             ('.1.3.6.1.2.1.1', ['1.0', '4.0', '5.0', '6.0']),  # type: ignore[arg-type]
-            backend=factory.backend(snmp_config),
         )
 
         if data:

cmk/base/snmp.py

@@ -20,21 +20,18 @@
 from cmk.utils.exceptions import MKBailOut, MKGeneralException
 from cmk.utils.log import console
 from cmk.utils.type_defs import (
-    ABCSNMPBackend,
-    DecodedString,
-    HostName,
     OID,
+    HostName,
     RawValue,
+    DecodedString,
     SNMPHostConfig,
     SNMPRowInfo,
 )
 
 import cmk.base.cleanup
 import cmk.base.config as config
 import cmk.base.ip_lookup as ip_lookup
-from cmk.fetchers import factory  # pylint: disable=cmk-module-layer-violation
-from cmk.fetchers.snmp_backend import (StoredWalkSNMPBackend  # pylint: disable=cmk-module-layer-violation,
-                                      )
+from cmk.fetchers.factory import SNMPBackendFactory  # pylint: disable=cmk-module-layer-violation
 
 try:
     from cmk.fetchers.cee.snmp_backend import inline  # pylint: disable=cmk-module-layer-violation, ungrouped-imports
@@ -71,8 +68,8 @@ def create_snmp_host_config(hostname):
 
 
 # Contextes can only be used when check_plugin_name is given.
-def get_single_oid(snmp_config, oid, check_plugin_name=None, do_snmp_scan=True, *, backend):
-    # type: (SNMPHostConfig, str, Optional[str], bool, ABCSNMPBackend) -> Optional[DecodedString]
+def get_single_oid(snmp_config, oid, check_plugin_name=None, do_snmp_scan=True):
+    # type: (SNMPHostConfig, str, Optional[str], bool) -> Optional[DecodedString]
     # The OID can end with ".*". In that case we do a snmpgetnext and try to
     # find an OID with the prefix in question. The *cache* is working including
     # the X, however.
@@ -93,7 +90,7 @@ def get_single_oid(snmp_config, oid, check_plugin_name=None, do_snmp_scan=True,
     console.vverbose("       Getting OID %s: " % oid)
     for context_name in snmp_config.snmpv3_contexts_of(check_plugin_name):
         try:
-            value = backend.get(
+            value = SNMPBackendFactory.get(
                 snmp_config,
                 oid=oid,
                 context_name=context_name,
@@ -123,7 +120,7 @@ def get_single_oid(snmp_config, oid, check_plugin_name=None, do_snmp_scan=True,
 
 def walk_for_export(snmp_config, oid):
     # type: (SNMPHostConfig, OID) -> SNMPRowInfoForStoredWalk
-    rows = StoredWalkSNMPBackend().walk(snmp_config, oid=oid)
+    rows = SNMPBackendFactory.walk(snmp_config, use_cache=False, oid=oid)
     return _convert_rows_for_stored_walk(rows)
 
 
@@ -323,10 +320,9 @@ def do_snmpget(oid, hostnames):
     for hostname in hostnames:
         #TODO what about SNMP management boards?
         snmp_config = create_snmp_host_config(hostname)
-        backend = factory.backend(snmp_config)
         snmp_cache.initialize_single_oid_cache(snmp_config)
 
-        value = get_single_oid(snmp_config, oid, backend=backend)
+        value = get_single_oid(snmp_config, oid)
         sys.stdout.write("%s (%s): %r\n" % (hostname, snmp_config.ipaddress, value))
         cmk.base.cleanup.cleanup_globals()
 

cmk/base/snmp_scan.py

@@ -21,7 +21,6 @@
 from cmk.base.api import PluginName
 from cmk.base.api.agent_based.section_types import SNMPDetectAtom, SNMPDetectSpec
 from cmk.base.snmp_utils import ScanFunction
-from cmk.fetchers import factory  # pylint: disable=cmk-module-layer-violation
 
 
 def _evaluate_snmp_detection(oid_function, detect_spec):
@@ -78,7 +77,6 @@ def _snmp_scan(host_config,
                for_mgmt_board=False):
     # type: (SNMPHostConfig, str, bool, bool, bool) -> Set[CheckPluginName]
     import cmk.base.inventory_plugins as inventory_plugins  # pylint: disable=import-outside-toplevel
-    backend = factory.backend(host_config)
 
     # Make hostname globally available for scan functions.
     # This is rarely used, but e.g. the scan for if/if64 needs
@@ -91,10 +89,7 @@ def _snmp_scan(host_config,
                                                         config.snmp_without_sys_descr):
         for oid, name in [(".1.3.6.1.2.1.1.1.0", "system description"),
                           (".1.3.6.1.2.1.1.2.0", "system object")]:
-            value = snmp.get_single_oid(host_config,
-                                        oid,
-                                        do_snmp_scan=do_snmp_scan,
-                                        backend=backend)
+            value = snmp.get_single_oid(host_config, oid, do_snmp_scan=do_snmp_scan)
             if value is None:
                 raise MKSNMPError(
                     "Cannot fetch %s OID %s. This might be OK for some bogus devices. "
@@ -133,11 +128,7 @@ def _snmp_scan(host_config,
 
             def oid_function(oid, default_value=None, cp_name=check_plugin_name):
                 # type: (OID, Optional[DecodedString], Optional[CheckPluginName]) -> Optional[DecodedString]
-                value = snmp.get_single_oid(host_config,
-                                            oid,
-                                            cp_name,
-                                            do_snmp_scan=do_snmp_scan,
-                                            backend=backend)
+                value = snmp.get_single_oid(host_config, oid, cp_name, do_snmp_scan=do_snmp_scan)
                 return default_value if value is None else value
 
             if callable(detection_spec):

cmk/fetchers/factory.py

@@ -6,7 +6,15 @@
 
 from typing import Optional
 
-from cmk.utils.type_defs import ABCSNMPBackend, SNMPHostConfig
+from cmk.utils.type_defs import (
+    ABCSNMPBackend,
+    CheckPluginName,
+    ContextName,
+    OID,
+    RawValue,
+    SNMPHostConfig,
+    SNMPRowInfo,
+)
 
 from .snmp_backend import ClassicSNMPBackend, StoredWalkSNMPBackend
 
@@ -15,7 +23,7 @@
 except ImportError:
     inline = None  # type: ignore[assignment]
 
-__all__ = ["backend"]
+__all__ = ["SNMPBackendFactory"]
 
 _force_stored_walks = False
 
@@ -31,14 +39,43 @@ def get_force_stored_walks():
     return _force_stored_walks
 
 
-def backend(snmp_config, *, use_cache=None):
-    # type: (SNMPHostConfig, Optional[bool]) -> ABCSNMPBackend
-    if use_cache is None:
-        use_cache = get_force_stored_walks()
-    if use_cache or snmp_config.is_usewalk_host:
-        return StoredWalkSNMPBackend()
+class SNMPBackendFactory(object):  # pylint: disable=useless-object-inheritance
+    @staticmethod
+    def _factory(snmp_config, *, use_cache):
+        # type: (SNMPHostConfig, Optional[bool]) -> ABCSNMPBackend
+        if use_cache is None:
+            use_cache = get_force_stored_walks()
+        if use_cache or snmp_config.is_usewalk_host:
+            return StoredWalkSNMPBackend()
 
-    if snmp_config.is_inline_snmp_host:
-        return inline.InlineSNMPBackend(snmp_config.record_stats)
+        if snmp_config.is_inline_snmp_host:
+            return inline.InlineSNMPBackend(snmp_config.record_stats)
 
-    return ClassicSNMPBackend()
+        return ClassicSNMPBackend()
+
+    @classmethod
+    def get(cls, snmp_config, *, oid, context_name=None, use_cache=None):
+        # type: (SNMPHostConfig, OID, Optional[ContextName], bool) -> Optional[RawValue]
+        return cls._factory(snmp_config, use_cache=use_cache).get(
+            snmp_config,
+            oid=oid,
+            context_name=context_name,
+        )
+
+    @classmethod
+    def walk(cls,
+             snmp_config,
+             *,
+             oid,
+             context_name=None,
+             check_plugin_name=None,
+             table_base_oid=None,
+             use_cache=None):
+        # type: (SNMPHostConfig, OID, Optional[ContextName], Optional[CheckPluginName], Optional[OID], Optional[bool]) -> SNMPRowInfo
+        return cls._factory(snmp_config, use_cache=use_cache).walk(
+            snmp_config,
+            oid=oid,
+            context_name=context_name,
+            check_plugin_name=check_plugin_name,
+            table_base_oid=table_base_oid,
+        )

cmk/fetchers/snmp.py

@@ -5,16 +5,13 @@
 # conditions defined in the file COPYING, which is part of this source code package.
 
 import logging
-from functools import partial
 from types import TracebackType
 from typing import Dict, List, Optional, Type, Union
 
 import cmk.utils.snmp_table as snmp_table
 from cmk.utils.check_utils import section_name_of
 from cmk.utils.type_defs import ABCSNMPTree, OIDInfo, RawSNMPData, SNMPHostConfig, SNMPTable
 
-from . import factory
-
 
 class SNMPDataFetcher:
     def __init__(
@@ -53,9 +50,7 @@ def data(self):
 
             # oid_info can now be a list: Each element  of that list is interpreted as one real oid_info
             # and fetches a separate snmp table.
-            get_snmp = partial(snmp_table.get_snmp_table_cached
-                               if self._use_snmpwalk_cache else snmp_table.get_snmp_table,
-                               backend=factory.backend(self._snmp_config))
+            get_snmp = snmp_table.get_snmp_table_cached if self._use_snmpwalk_cache else snmp_table.get_snmp_table
             if isinstance(oid_info, list):
                 # branch: List[ABCSNMPTree]
                 check_info = []  # type: List[SNMPTable]

cmk/utils/snmp_table.py

@@ -21,7 +21,6 @@
     OID_END_BIN,
     OID_END_OCTET_STRING,
     OID_STRING,
-    ABCSNMPBackend,
     ABCSNMPTree,
     CheckPluginName,
     Column,
@@ -42,19 +41,21 @@
     SNMPValueEncoding,
 )
 
+from cmk.fetchers.factory import SNMPBackendFactory  # pylint: disable=cmk-module-layer-violation
+
 ResultColumnsUnsanitized = List[Tuple[OID, SNMPRowInfo, SNMPValueEncoding]]
 ResultColumnsSanitized = List[Tuple[List[RawValue], SNMPValueEncoding]]
 ResultColumnsDecoded = List[List[DecodedValues]]
 
 
-def get_snmp_table(snmp_config, check_plugin_name, oid_info, *, backend):
-    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree], ABCSNMPBackend) -> SNMPTable
-    return _get_snmp_table(snmp_config, check_plugin_name, oid_info, False, backend=backend)
+def get_snmp_table(snmp_config, check_plugin_name, oid_info):
+    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree]) -> SNMPTable
+    return _get_snmp_table(snmp_config, check_plugin_name, oid_info, False)
 
 
-def get_snmp_table_cached(snmp_config, check_plugin_name, oid_info, *, backend):
-    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree], ABCSNMPBackend) -> SNMPTable
-    return _get_snmp_table(snmp_config, check_plugin_name, oid_info, True, backend=backend)
+def get_snmp_table_cached(snmp_config, check_plugin_name, oid_info):
+    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree]) -> SNMPTable
+    return _get_snmp_table(snmp_config, check_plugin_name, oid_info, True)
 
 
 SPECIAL_COLUMNS = [
@@ -67,8 +68,8 @@ def get_snmp_table_cached(snmp_config, check_plugin_name, oid_info, *, backend):
 
 
 # TODO: OID_END_OCTET_STRING is not used at all. Drop it.
-def _get_snmp_table(snmp_config, check_plugin_name, oid_info, use_snmpwalk_cache, *, backend):
-    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree], bool, ABCSNMPBackend) -> SNMPTable
+def _get_snmp_table(snmp_config, check_plugin_name, oid_info, use_snmpwalk_cache):
+    # type: (SNMPHostConfig, CheckPluginName, Union[OIDInfo, ABCSNMPTree], bool) -> SNMPTable
     oid, suboids, targetcolumns = _make_target_columns(oid_info)
 
     index_column = -1
@@ -96,13 +97,8 @@ def _get_snmp_table(snmp_config, check_plugin_name, oid_info, use_snmpwalk_cache
                     "You can only use one of OID_END, OID_STRING, OID_BIN, OID_END_BIN and OID_END_OCTET_STRING."
                 )
 
-            rowinfo = _get_snmpwalk(snmp_config,
-                                    check_plugin_name,
-                                    oid,
-                                    fetchoid,
-                                    column,
-                                    use_snmpwalk_cache,
-                                    backend=backend)
+            rowinfo = _get_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid, column,
+                                    use_snmpwalk_cache)
 
             if column in SPECIAL_COLUMNS:
                 index_column = len(columns)
@@ -245,9 +241,8 @@ def _key_oid_pairs(pair1):
     return _oid_to_intlist(pair1[0].lstrip('.'))
 
 
-def _get_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid, column, use_snmpwalk_cache, *,
-                  backend):
-    # type: (SNMPHostConfig, CheckPluginName, OID, OID, Column, bool, ABCSNMPBackend) -> SNMPRowInfo
+def _get_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid, column, use_snmpwalk_cache):
+    # type: (SNMPHostConfig, CheckPluginName, OID, OID, Column, bool) -> SNMPRowInfo
     if column in SPECIAL_COLUMNS:
         return []
 
@@ -256,23 +251,23 @@ def _get_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid, column, use_snm
     cached = _get_cached_snmpwalk(snmp_config.hostname, fetchoid) if get_from_cache else None
     if cached is not None:
         return cached
-    rowinfo = _perform_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid, backend=backend)
+    rowinfo = _perform_snmpwalk(snmp_config, check_plugin_name, oid, fetchoid)
     if save_to_cache:
         _save_snmpwalk_cache(snmp_config.hostname, fetchoid, rowinfo)
     return rowinfo
 
 
-def _perform_snmpwalk(snmp_config, check_plugin_name, base_oid, fetchoid, *, backend):
-    # type: (SNMPHostConfig, CheckPluginName, OID, OID, ABCSNMPBackend) -> SNMPRowInfo
+def _perform_snmpwalk(snmp_config, check_plugin_name, base_oid, fetchoid):
+    # type: (SNMPHostConfig, CheckPluginName, OID, OID) -> SNMPRowInfo
     added_oids = set([])  # type: Set[OID]
     rowinfo = []  # type: SNMPRowInfo
 
     for context_name in snmp_config.snmpv3_contexts_of(check_plugin_name):
-        rows = backend.walk(snmp_config,
-                            oid=fetchoid,
-                            check_plugin_name=check_plugin_name,
-                            table_base_oid=base_oid,
-                            context_name=context_name)
+        rows = SNMPBackendFactory.walk(snmp_config,
+                                       oid=fetchoid,
+                                       check_plugin_name=check_plugin_name,
+                                       table_base_oid=base_oid,
+                                       context_name=context_name)
 
         # I've seen a broken device (Mikrotik Router), that broke after an
         # update to RouterOS v6.22. It would return 9 time the same OID when