implement creds in-memory cache solution (#139)

* implement creds inmemory cache solution

nautobot_plugin_nornir/plugins/credentials/nautobot_secrets.py

@@ -1,42 +1,118 @@
-"""Credentials class designed to work with Nautobot Secrets Functionality."""
+"""
+Credentials class designed to work with Nautobot Secrets Functionality.
+
+Nautobot Secrets Feature:
+
+secret-group:
+    secret: username <supports templating>
+        - Because of templating can be `n` number of actual values.
+    secret: password <supports templating>
+        - Because of templating can be `n` number of actual values.
+    secret: secret <supports templating>
+        - Because of templating can be `n` number of actual values.
+
+Caching Solution:
+
+creds_cache = {
+        "hashed key": "value"
+    }
+
+    - "hashed key" is the rendred.parameter which is post template rendered secret key.
+    - "value" is the literal secrets value.
+"""
 # pylint: disable=attribute-defined-outside-init
+import json
 
 from nautobot.extras.choices import SecretsGroupAccessTypeChoices, SecretsGroupSecretTypeChoices
-from nautobot.extras.models.secrets import SecretsGroupAssociation
 from nautobot_plugin_nornir.constants import PLUGIN_CFG
 
 from .nautobot_orm import MixinNautobotORMCredentials
 
 
-def _get_secret_value(secret_type, device_obj):
-    """Get value for a secret based on secret type and device.
+def _get_access_type_value(device_obj):
+    """Get value for access_type.
 
     Args:
-        secret_type (SecretsGroupSecretTypeChoices): Type of secret to check.
         device_obj (dcim.models.Device): Nautobot device object.
 
     Returns:
-        str: Secret value.
+        SecretsGroupAccessTypeChoices: Choice
     """
     if PLUGIN_CFG.get("use_config_context", {}).get("secrets"):
         access_type_str = device_obj.get_config_context()["nautobot_plugin_nornir"]["secret_access_type"].upper()
         access_type = getattr(SecretsGroupAccessTypeChoices, f"TYPE_{access_type_str}")
     else:
         access_type = SecretsGroupAccessTypeChoices.TYPE_GENERIC
-    try:
-        value = device_obj.secrets_group.get_secret_value(
-            access_type=access_type,
-            secret_type=secret_type,
-            obj=device_obj,
-        )
-    except SecretsGroupAssociation.DoesNotExist:
-        value = None
-    return value
+    return access_type
 
 
 class CredentialsNautobotSecrets(MixinNautobotORMCredentials):
     """Credentials Class designed to work with Nautobot Secrets Functionality."""
 
+    def __init__(self):
+        """Initialize class with empty creds_cache."""
+        self._creds_cache = {}
+
+    def _get_or_cache_secret_key(self, device, sec):
+        """Check if secret_key is already in cache, if not call setter method to add the entry.
+
+        Args:
+            device (dcim.Device): Nautobot Device object.
+            sec (extra.SecretGroup): Nautobot SecretGroup objects.
+
+        Returns:
+            str: A rendered secgret group hashed into a single hashed id to use as a unique key.
+
+        Examples:
+            >>> # Example of a Environment Variable rendered.
+            >>> device = Device.objects.first()
+            >>> sec = device.secrets_group.secrets.last()
+            >>> sec
+            >>> <Secret: router-u>
+            >>> sec.rendered_parameters(obj=device)
+            >>> {'variable': 'DEVICE_ROUTER_USERNAME'}
+            >>> str(hash(json.dumps(sec.rendered_parameters(obj=device), sort_keys=True)))
+            >>> '588946476233721127'
+            >>>
+            >>> # Example using hashicorp vault secrets provider backend.
+            >>> sec = device.secrets_group.secrets.first()
+            >>> sec.rendered_parameters(obj=device)
+            >>>
+            {'key': 'username',
+            'path': 'goldenconfig',
+            'kv_version': 'v2',
+            'mount_point': 'secret'}
+            >>> str(hash(json.dumps(sec.rendered_parameters(obj=device), sort_keys=True)))
+            >>> '-3888945057722956687'
+        """
+        # hash the rendered secrets params.
+        secret_key_hash = str(hash(json.dumps(sec.rendered_parameters(obj=device), sort_keys=True)))
+        if not self.creds_cache.get(secret_key_hash):
+            # If hashed value isn't in the cache, then call actual get_value to pull secret value itself and
+            # Update the cache property.
+            self.creds_cache = {secret_key_hash: sec.get_value(obj=device)}
+        return secret_key_hash
+
+    @property
+    def creds_cache(self):
+        """
+        Getter for in memory creds cache. This is useds to temporarily cache secrets-group creds to avoid re-querying secrets providers over and over per device if the same secret-group was used.
+
+        Example:
+            {"123435": 'supersecret'}
+        """
+        return self._creds_cache
+
+    @creds_cache.setter
+    def creds_cache(self, new_cred):
+        """
+        Setter for creds_cache.
+
+        Args:
+            new_cred (dict): new secret group key and values.
+        """
+        self._creds_cache.update(new_cred)
+
     def get_device_creds(self, device):
         """Return the credentials for a given device.
 
@@ -49,13 +125,31 @@ def get_device_creds(self, device):
             secret (string):
         """
         if device.secrets_group:
-            self.username = _get_secret_value(
-                secret_type=SecretsGroupSecretTypeChoices.TYPE_USERNAME, device_obj=device
-            )
-            self.password = _get_secret_value(
-                secret_type=SecretsGroupSecretTypeChoices.TYPE_PASSWORD, device_obj=device
-            )
-            self.secret = _get_secret_value(secret_type=SecretsGroupSecretTypeChoices.TYPE_SECRET, device_obj=device)
+            self.secret = None
+            for sec in device.secrets_group.secrets.all():
+                secret_value = self.creds_cache.get(self._get_or_cache_secret_key(device, sec))
+                current_secret_type = getattr(
+                    SecretsGroupSecretTypeChoices, f"TYPE_{sec.secrets_group_associations.first().secret_type.upper()}"
+                )
+                current_access_type = getattr(
+                    SecretsGroupAccessTypeChoices, f"TYPE_{sec.secrets_group_associations.first().access_type.upper()}"
+                )
+                configured_access_type = _get_access_type_value(device)
+                if (
+                    current_secret_type == SecretsGroupSecretTypeChoices.TYPE_USERNAME
+                    and configured_access_type == current_access_type
+                ):
+                    self.username = secret_value
+                if (
+                    current_secret_type == SecretsGroupSecretTypeChoices.TYPE_PASSWORD
+                    and configured_access_type == current_access_type
+                ):
+                    self.password = secret_value
+                if (
+                    current_secret_type == SecretsGroupSecretTypeChoices.TYPE_SECRET
+                    and configured_access_type == current_access_type
+                ):
+                    self.secret = secret_value
             if not self.secret:
                 self.secret = self.password
             return (self.username, self.password, self.secret)