Add User Definable Variable Substitution

charts/vc-authn-oidc/templates/deployment.yaml

@@ -39,6 +39,12 @@ spec:
         - name: auth-session-ttl
           configMap:
             name: {{ include "global.fullname" . }}-session-timeout
+        - name: custom-variable-substitution
+          configMap:
+            name:  {{ include "global.fullname" . }}-variable-substitution-config
+            items:
+              - key: user_variable_substitution.py
+                path: user_variable_substitution.py
       containers:
         - name: {{ .Chart.Name }}
           securityContext:
@@ -72,6 +78,8 @@ spec:
               value: {{ .Values.controller.presentationExpireTime | quote }}
             # - name: CONTROLLER_SESSION_TIMEOUT_CONFIG_FILE
             #   value: /home/aries/sessiontimeout.json
+            - name: CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE
+              value: /home/aries/user_variable_substitution.py
             - name: CONTROLLER_PRESENTATION_CLEANUP_TIME
               value: {{ .Values.controller.sessionTimeout.duration | quote }}
             - name: ACAPY_AGENT_URL
@@ -133,6 +141,9 @@ spec:
             - name: auth-session-ttl
               mountPath: /home/aries/sessiontimeout.json
               subPath: sessiontimeout.json
+            - name: custom-variable-substitution
+              mountPath: /home/aries/user_variable_substitution.py
+              subPath: user_variable_substitution.py
       {{- with .Values.nodeSelector }}
       nodeSelector:
         {{- toYaml . | nindent 8 }}

docker/docker-compose.yaml

@@ -27,6 +27,7 @@ services:
       - CONTROLLER_PRESENTATION_EXPIRE_TIME=${CONTROLLER_PRESENTATION_EXPIRE_TIME}
       - CONTROLLER_PRESENTATION_CLEANUP_TIME=${CONTROLLER_PRESENTATION_CLEANUP_TIME}
       - CONTROLLER_SESSION_TIMEOUT_CONFIG_FILE=${CONTROLLER_SESSION_TIMEOUT_CONFIG_FILE}
+      - CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE=${CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE}
       - ACAPY_TENANCY=${AGENT_TENANT_MODE}
       - ACAPY_AGENT_URL=${AGENT_ENDPOINT}
       - ACAPY_ADMIN_URL=${AGENT_ADMIN_URL}
@@ -45,6 +46,7 @@ services:
     volumes:
       - ../oidc-controller:/app:rw
       - ./oidc-controller/config/sessiontimeout.json:/home/aries/sessiontimeout.json
+      - ./oidc-controller/config/user_variable_substitution.py:/home/aries/user_variable_substitution.py
     networks:
       - vc_auth
 

docker/manage

@@ -179,6 +179,9 @@ configureEnvironment() {
   # The path to the auth_session timeouts config file
   export CONTROLLER_SESSION_TIMEOUT_CONFIG_FILE="/home/aries/sessiontimeout.json"
 
+  # Extend Variable Substitutions
+  export CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE="/home/aries/user_variable_substitution.py"
+
   #controller app settings
   export INVITATION_LABEL=${INVITATION_LABEL:-"VC-AuthN"}
   export SET_NON_REVOKED="True"

docker/oidc-controller/config/user_variable_substitution_example.py

@@ -0,0 +1,24 @@
+def sub_days_plus_one(days: str) -> int:
+    """Strings like '$sub_days_plus_one_4' will be replaced with the
+    final number incremented by one. In this case 5.
+    $sub_days_plus_one_4 -> 5
+    $sub_days_plus_one_10 -> 11"""
+    return int(days) + 1
+
+
+variable_substitution_map.add_variable_substitution(
+    r"\$sub_days_plus_one_(\d+)", sub_days_plus_one
+)
+
+
+def sub_string_for_sure(_: str) -> str:
+    """Turns strings like $sub_string_for_sure_something into the string 'sure'
+    $sub_string_for_sure_something -> sure
+    $sub_string_for_sure_i -> sure
+    """
+    return "sure"
+
+
+variable_substitution_map.add_variable_substitution(
+    r"\$sub_string_for_sure_(.+)", sub_string_for_sure
+)

docs/ConfigurationGuide.md

@@ -125,12 +125,42 @@ and at runtime when the user navigates to the QR code page, the proof would incl
 See the `oidc-controller\api\verificationConfigs\variableSubstitutions.py` file for implementations.
 
 #### Customizing variables
+For user defined variable substitutions users can set the environment
+variable to point at a python file defining new substitutions.
 
-In `oidc-controller\api\verificationConfigs\variableSubstitutions.py` there are the built-in variables above.
-For an advanced use case, if you require further customization, it could be possible to just replace that `variableSubstitutions.py` file 
-in a VC-AuthN implementation and the newly introduced variables would be run if they are included in a proof request configuration.
+##### User Defined Variable API
+In `oidc-controller\api\verificationConfigs\variableSubstitutions.py`
+you will find the method `add_variable_substitution` which can be used
+to modify the existing instance of `VariableSubstitutionMap` named
+`variable_substitution_map`.
 
-For regular variables they can be added to the `static_map`, mapping your variable name to a function doing the operation.  
-For "dynamic" ones alter `__contains__` and `__getitem__` to use a regex to parse and extract what is needed.
+Takes a valid regular expression `pattern` and a function who's
+arguments correspond with each regex group `substitution_function`. Each
+captured regex group will be passed to the function as a `str`.
 
-The file `oidc-controller\api\verificationConfigs\helpers.py` contains the function that recurses through the config doing any substitutions, so it would pick up whatever is available in `variableSubstitutions.py` 
+Here is an example python file that would define a new variable
+substitution `$today_plus_x_times_y` which will add X days multiplied
+by Y days to today's date
+
+```python
+from datetime import datetime, timedelta
+
+def today_plus_times(added_days: str, multiplied_days: str) -> int:
+	return int(
+		((datetime.today() + timedelta(days=int(added_days))) * timedelta(days=int(multiplied_days)))
+	).strftime("%Y%m%d"))
+
+# variable_substitution_map will already be defined in variableSubstitutions.py
+variable_substitution_map.add_variable_substitution(r"\$today_plus_(\d+)_times_(\d+)", today_plus_times)
+```
+
+For an example of this python file see `docker/oidc-controller/config/user_variable_substitution_example.py`
+
+All that is necessary is the adding of substitution variables.These
+changes will be applied by vc-authn during startup. The variable
+`variable_substitution_map` **will already be defined**.
+
+After loading the python file during the service startup each new user
+defined variable is logged for confirmation. Any failures to load
+these changes will be logged. If no new definitions are found
+indication of this will also be logged

oidc-controller/api/core/config.py

@@ -8,6 +8,7 @@
 from pathlib import Path
 from pydantic_settings import BaseSettings
 from pydantic import ConfigDict
+from typing import Any
 
 import structlog
 
@@ -227,6 +228,9 @@ class GlobalConfig(BaseSettings):
     )
     SET_NON_REVOKED: bool = strtobool(os.environ.get("SET_NON_REVOKED", True))
 
+    CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE: str | None = os.environ.get(
+        "CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE"
+    )
     model_config = ConfigDict(case_sensitive=True)
 
 

oidc-controller/api/verificationConfigs/tests/test_variable_substitutions.py

@@ -1,4 +1,5 @@
 import time
+from typing_extensions import Callable
 import pytest
 from datetime import datetime, timedelta
 from api.verificationConfigs.variableSubstitutions import VariableSubstitutionMap
@@ -27,7 +28,17 @@ def test_get_threshold_years_date():
     expected_date = (
         datetime.today().replace(year=datetime.today().year - years).strftime("%Y%m%d")
     )
-    assert vsm.get_threshold_years_date(years) == int(expected_date)
+    assert vsm.get_threshold_years_date(str(years)) == int(expected_date)
+
+
+def test_user_defined_func():
+    vsm = VariableSubstitutionMap()
+    func: Callable[[int], int] = lambda x, y: int(x) + int(y)
+    vsm.add_variable_substitution(r"\$years since (\d+) (\d+)", func)
+    days = 10
+    years = 22
+    assert f"$years since {years} {days}" in vsm
+    assert vsm[f"$years since {years} {days}"]() == years + days
 
 
 def test_contains_static_variable():

oidc-controller/api/verificationConfigs/variableSubstitutions.py

@@ -8,6 +8,15 @@
 from datetime import datetime, timedelta
 import time
 import re
+import copy
+
+import structlog
+from typing_extensions import Callable
+from ..core.config import settings
+
+logger: structlog.typing.FilteringBoundLogger = structlog.getLogger(__name__)
+
+SubstitutionFunction = Callable[..., int | str]
 
 
 class VariableSubstitutionMap:
@@ -20,7 +29,25 @@ def __init__(self):
             "$tomorrow_int": self.get_tomorrow_date,
         }
 
-    def get_threshold_years_date(self, years: int) -> int:
+        self.user_static_map: dict[re.Pattern[str], SubstitutionFunction] = {
+            re.compile(r"\$threshold_years_(\d+)"): self.get_threshold_years_date
+        }
+
+    def add_variable_substitution(
+        self, pattern: str, substitution_function: SubstitutionFunction
+    ):
+        """Takes a valid regular expression PATTERN and a function
+        who's arguments correspond with each regex group
+        SUBSTITUTION_FUNCTION. Each captured regex group will be
+        passed to the function as a str.
+
+        Examples:
+        vsm.add_variable_substitution(r\"\\$years since (\\d+) (\\d+)\", lambda x, y: int(x) + int(y))
+        vsm[f"$years since {10} {12}"] => 22
+        """
+        self.user_static_map[re.compile(pattern)] = substitution_function
+
+    def get_threshold_years_date(self, years: str) -> int:
         """
         Calculate the threshold date for a given number of years.
 
@@ -30,7 +57,9 @@ def get_threshold_years_date(self, years: int) -> int:
         Returns:
             int: The current date minux X years in YYYYMMDD format.
         """
-        threshold_date = datetime.today().replace(year=datetime.today().year - years)
+        threshold_date = datetime.today().replace(
+            year=datetime.today().year - int(years)
+        )
         return int(threshold_date.strftime("%Y%m%d"))
 
     def get_now(self) -> int:
@@ -63,16 +92,47 @@ def get_tomorrow_date(self) -> int:
     # For "dynamic" variables, use a regex to match the key and return a lambda function
     # So a proof request can use $threshold_years_X to get the years back for X years
     def __contains__(self, key: str) -> bool:
-        return key in self.static_map or re.match(r"\$threshold_years_(\d+)", key)
+        res = key in self.static_map
+        if not res:
+            for i in self.user_static_map.keys():
+                if re.match(i, key):
+                    return True
+        return res
 
     def __getitem__(self, key: str):
         if key in self.static_map:
             return self.static_map[key]
-        match = re.match(r"\$threshold_years_(\d+)", key)
-        if match:
-            return lambda: self.get_threshold_years_date(int(match.group(1)))
+        for i, j in self.user_static_map.items():
+            if nmatch := re.match(i, key):
+                return lambda: j(*nmatch.groups())
         raise KeyError(f"Key {key} not found in format_args_function_map")
 
 
 # Create an instance of the custom mapping class
 variable_substitution_map = VariableSubstitutionMap()
+
+
+def apply_user_variables():
+    try:
+        with open(settings.CONTROLLER_VARIABLE_SUBSTITUTION_OVERRIDE) as user_file:
+            code = user_file.read()
+    except TypeError:
+        logger.warning("No user defined variable substitutions file provided")
+        return None
+    except FileNotFoundError:
+        logger.warning("User defined variable substitutions file could not be found")
+        return None
+    else:
+        og_substitution_map = copy.copy(variable_substitution_map.user_static_map)
+        exec(code)
+        if len(variable_substitution_map.user_static_map) <= 1:
+            logger.info("No new user created variable substitution where found")
+
+        for pattern, func in variable_substitution_map.user_static_map.items():
+            if pattern not in og_substitution_map:
+                logger.info(
+                    f'New user created variable substitution: The pattern "{pattern.pattern}" is now mapped to the function {func.__name__}'
+                )
+
+
+apply_user_variables()