WIP: implement _SnapFsConfigManager using slurmutils

dev-requirements.txt

@@ -1,2 +1,10 @@
+# lib deps
+slurmutils ~= 0.6.0
+python-dotenv ~= 1.0.1
+pyyaml >= 6.0.2
+
+# tests deps
+coverage[toml] ~= 7.6
+pyfakefs ~= 5.6.0
 pytest ~= 7.2
 pytest-order ~= 1.1

lib/charms/hpc_libs/v0/slurm_ops.py

@@ -67,19 +67,24 @@ def _on_install(self, _) -> None:
     "SnapManager",
 ]
 
-import json
 import logging
+import os
 import re
 import socket
 import subprocess
 from abc import ABC, abstractmethod
 from collections.abc import Mapping
+from contextlib import AbstractContextManager
 from enum import Enum
+from functools import partial
 from pathlib import Path
-from typing import Any, Optional, Type
+from typing import Any, Callable, Optional, Type, TypeAlias
 
 import dotenv
 import yaml
+from slurmutils.editors import slurmconfig, slurmdbdconfig
+from slurmutils.exceptions import ModelError
+from slurmutils.models.model import BaseModel as SlurmBaseConfig
 
 # The unique Charmhub library identifier, never change it
 LIBID = "541fd767f90b40539cf7cd6e7db8fabf"
@@ -92,7 +97,7 @@ def _on_install(self, _) -> None:
 LIBPATCH = 6
 
 # Charm library dependencies to fetch during `charmcraft pack`.
-PYDEPS = ["pyyaml>=6.0.2", "python-dotenv~=1.0.1"]
+PYDEPS = ["pyyaml>=6.0.2", "python-dotenv~=1.0.1", "slurmutils~=0.6.0"]
 
 _logger = logging.getLogger(__name__)
 _acronym = re.compile(r"(?<=[A-Z])(?=[A-Z][a-z])")
@@ -381,7 +386,7 @@ def get(self, key: Optional[str] = None) -> Any:
 
     def set(self, config: Mapping[str, Any]) -> None:
         """Set configuration for Slurm component."""
-        # Sanity check to avoid modifying the .env if the input keys are invalid.
+        # Check to avoid modifying the .env if the input keys are invalid.
         for key in config.keys():
             if key not in self._keys:
                 raise SlurmOpsError(
@@ -393,7 +398,7 @@ def set(self, config: Mapping[str, Any]) -> None:
 
     def unset(self, *keys: str) -> None:
         """Unset configuration for Slurm component."""
-        # Sanity check to avoid modifying the .env if the input keys are invalid.
+        # Check to avoid modifying the .env if the input keys are invalid.
         for key in keys:
             if key not in self._keys:
                 raise SlurmOpsError(
@@ -407,27 +412,64 @@ def unset(self, *keys: str) -> None:
             dotenv.unset_key(self._DOTENV_FILE, self.config_to_env_var(key))
 
 
-class _SnapConfigManager(ConfigManager):
-    """Control configuration of a Slurm component using Snap."""
+_EditorFetcher: TypeAlias = Callable[[], AbstractContextManager[SlurmBaseConfig]]
+_ConfigFetcher: TypeAlias = Callable[[], SlurmBaseConfig]
+_ConfigDeleter: TypeAlias = Callable[[], list]
 
-    def __init__(self, service: ServiceType) -> None:
-        self._name = service.config_name
+
+# TODO: probably move this abstraction (or something similar that enables the same) to slurmutils
+class _SnapFsConfigManager(ConfigManager, ABC):
+    """Control configuration of a Slurm component using a file."""
+
+    def __init__(
+        self, editor: _EditorFetcher, config: _ConfigFetcher, deleter=_ConfigDeleter
+    ) -> None:
+        self._editor_fetcher = editor
+        self._config_fetcher = config
+        self._config_deleter = deleter
 
     def get(self, key: Optional[str] = None) -> Any:
         """Get specific configuration value for Slurm component."""
-        key = f"{self._name}.{key}" if key else self._name
-        config = json.loads(_snap("get", "-d", "slurm", key))
-        return config[key]
+        config = self._config_fetcher().dict()
+
+        try:
+            for prop in key.split("."):
+                if isinstance(config, dict):
+                    config = config[prop]
+                elif isinstance(config, list):
+                    config = config[int(prop)]
+                else:
+                    raise SlurmOpsError(f"invalid configuration key `{key}`")
+            return config
+        except ModelError as e:
+            raise SlurmOpsError(e.message)
+        except KeyError:
+            raise SlurmOpsError(f"invalid configuration key `{key}`")
 
     def set(self, config: Mapping[str, Any]) -> None:
         """Set configuration for Slurm component."""
-        args = [f"{self._name}.{k}={json.dumps(v)}" for k, v in config.items()]
-        _snap("set", "slurm", *args)
+        with self._config_fetcher() as current_config:
+            new_config = current_config.from_dict(config)
+            current_config.update(new_config)
 
     def unset(self, *keys: str) -> None:
         """Unset configuration for Slurm component."""
-        args = [f"{self._name}.{k}" for k in keys] if len(keys) > 0 else [self._name]
-        _snap("unset", "slurm", *args)
+        if len(keys) == 0:
+            self._config_deleter()
+            return
+
+        with self._config_fetcher() as current_config:
+            for key in keys:
+                rest, last = key.rsplit(".", 1)
+                base = current_config
+                try:
+                    for prop in rest.split("."):
+                        base = getattr(base, prop)
+                    del base[last]
+                except ModelError as e:
+                    raise SlurmOpsError(e.message)
+                except KeyError:
+                    raise SlurmOpsError(f"invalid configuration key `{key}`")
 
 
 class _SnapMungeKeyManager(MungeKeyManager):
@@ -470,8 +512,16 @@ class SnapManager(SlurmOpsManager):
     """Slurm ops manager that uses Snap as its package manager."""
 
     _CONFIG_SERVICES = {
-        ServiceType.SLURMCTLD: _SnapConfigManager(ServiceType.SLURMCTLD),
-        ServiceType.SLURMDBD: _SnapConfigManager(ServiceType.SLURMDBD),
+        ServiceType.SLURMCTLD: _SnapFsConfigManager(
+            editor=partial(slurmconfig.edit, "/var/snap/slurm/common/etc/slurm/slurm.conf"),
+            config=partial(slurmconfig.load, "/var/snap/slurm/common/etc/slurm/slurm.conf"),
+            deleter=partial(os.remove, "/var/snap/slurm/common/etc/slurm/slurm.conf"),
+        ),
+        ServiceType.SLURMDBD: _SnapFsConfigManager(
+            editor=partial(slurmdbdconfig.edit, "/var/snap/slurm/common/etc/slurm/slurmdbd.conf"),
+            config=partial(slurmdbdconfig.load, "/var/snap/slurm/common/etc/slurm/slurmdbd.conf"),
+            deleter=partial(os.remove, "/var/snap/slurm/common/etc/slurm/slurmdbd.conf"),
+        ),
         ServiceType.MUNGED: _SnapEnvConfigManager(ServiceType.MUNGED.value, ["max-thread-count"]),
         ServiceType.SLURMD: _SnapEnvConfigManager(ServiceType.SLURMD.value, ["config-server"]),
         ServiceType.PROMETHEUS_EXPORTER: _SnapEnvConfigManager(

requirements.txt

@@ -1,4 +1 @@
 ops ~= 2.5
-slurmutils ~= 0.4.0
-python-dotenv ~= 1.0.1
-pyyaml >= 6.0.2