7 files changed, 96 insertions, 10 deletions
diff --git a/src/services/api/graphql/bindings.py b/src/services/api/graphql/bindings.py
index 049d59de7..0b1260912 100644
--- a/src/services/api/graphql/bindings.py
+++ b/src/services/api/graphql/bindings.py
@@ -17,6 +17,7 @@ import vyos.defaults
 from . graphql.queries import query
 from . graphql.mutations import mutation
 from . graphql.directives import directives_dict
+from . graphql.errors import op_mode_error
 from . utils.schema_from_op_mode import generate_op_mode_definitions
 from ariadne import make_executable_schema, load_schema_from_path, snake_case_fallback_resolvers
 
@@ -27,6 +28,6 @@ def generate_schema():
 
     type_defs = load_schema_from_path(api_schema_dir)
 
-    schema = make_executable_schema(type_defs, query, mutation, snake_case_fallback_resolvers, directives=directives_dict)
+    schema = make_executable_schema(type_defs, query, op_mode_error, mutation, snake_case_fallback_resolvers, directives=directives_dict)
 
     return schema
diff --git a/src/services/api/graphql/graphql/errors.py b/src/services/api/graphql/graphql/errors.py
new file mode 100644
index 000000000..1066300e0
--- /dev/null
+++ b/src/services/api/graphql/graphql/errors.py
@@ -0,0 +1,8 @@
+
+from ariadne import InterfaceType
+
+op_mode_error = InterfaceType("OpModeError")
+
+@op_mode_error.type_resolver
+def resolve_op_mode_error(obj, *_):
+    return obj['name']
diff --git a/src/services/api/graphql/graphql/mutations.py b/src/services/api/graphql/graphql/mutations.py
index c8ae0f516..1b77cff87 100644
--- a/src/services/api/graphql/graphql/mutations.py
+++ b/src/services/api/graphql/graphql/mutations.py
@@ -22,6 +22,8 @@ from makefun import with_signature
 from .. import state
 from .. import key_auth
 from api.graphql.session.session import Session
+from api.graphql.session.errors.op_mode_errors import op_mode_err_msg, op_mode_err_code
+from vyos.opmode import Error as OpModeError
 
 mutation = ObjectType("Mutation")
 
@@ -86,10 +88,19 @@ def make_mutation_resolver(mutation_name, class_name, session_func):
                 "success": True,
                 "data": data
             }
+        except OpModeError as e:
+            typename = type(e).__name__
+            return {
+                "success": False,
+                "errore": ['op_mode_error'],
+                "op_mode_error": {"name": f"{typename}",
+                                 "message": op_mode_err_msg.get(typename, "Unknown"),
+                                 "vyos_code": op_mode_err_code.get(typename, 9999)}
+            }
         except Exception as error:
             return {
                 "success": False,
-                "errors": [str(error)]
+                "errors": [repr(error)]
             }
 
     return func_impl
diff --git a/src/services/api/graphql/graphql/queries.py b/src/services/api/graphql/graphql/queries.py
index 921a66274..8ae61b704 100644
--- a/src/services/api/graphql/graphql/queries.py
+++ b/src/services/api/graphql/graphql/queries.py
@@ -22,6 +22,8 @@ from makefun import with_signature
 from .. import state
 from .. import key_auth
 from api.graphql.session.session import Session
+from api.graphql.session.errors.op_mode_errors import op_mode_err_msg, op_mode_err_code
+from vyos.opmode import Error as OpModeError
 
 query = ObjectType("Query")
 
@@ -86,10 +88,19 @@ def make_query_resolver(query_name, class_name, session_func):
                 "success": True,
                 "data": data
             }
+        except OpModeError as e:
+            typename = type(e).__name__
+            return {
+                "success": False,
+                "errors": ['op_mode_error'],
+                "op_mode_error": {"name": f"{typename}",
+                                 "message": op_mode_err_msg.get(typename, "Unknown"),
+                                 "vyos_code": op_mode_err_code.get(typename, 9999)}
+            }
         except Exception as error:
             return {
                 "success": False,
-                "errors": [str(error)]
+                "errors": [repr(error)]
             }
 
     return func_impl
diff --git a/src/services/api/graphql/session/errors/op_mode_errors.py b/src/services/api/graphql/session/errors/op_mode_errors.py
new file mode 100644
index 000000000..7ba75455d
--- /dev/null
+++ b/src/services/api/graphql/session/errors/op_mode_errors.py
@@ -0,0 +1,13 @@
+
+
+op_mode_err_msg = {
+    "UnconfiguredSubsystem": "subsystem is not configured or not running",
+    "DataUnavailable": "data currently unavailable",
+    "PermissionDenied": "client does not have permission"
+}
+
+op_mode_err_code = {
+    "UnconfiguredSubsystem": 2000,
+    "DataUnavailable": 2001,
+    "PermissionDenied": 1003
+}
diff --git a/src/services/api/graphql/session/session.py b/src/services/api/graphql/session/session.py
index 23bc7154c..93e1c328e 100644
--- a/src/services/api/graphql/session/session.py
+++ b/src/services/api/graphql/session/session.py
@@ -22,6 +22,7 @@ from vyos.config import Config
 from vyos.configtree import ConfigTree
 from vyos.defaults import directories
 from vyos.template import render
+from vyos.opmode import Error as OpModeError
 
 from api.graphql.utils.util import load_op_mode_as_module, split_compound_op_mode_name
 
@@ -177,10 +178,10 @@ class Session:
 
         mod = load_op_mode_as_module(f'{scriptname}')
         func = getattr(mod, func_name)
-        if len(list(data)) > 0:
+        try:
             res = func(True, **data)
-        else:
-            res = func(True)
+        except OpModeError as e:
+            raise e
 
         return res
 
@@ -199,9 +200,9 @@ class Session:
 
         mod = load_op_mode_as_module(f'{scriptname}')
         func = getattr(mod, func_name)
-        if len(list(data)) > 0:
+        try:
             res = func(**data)
-        else:
-            res = func()
+        except OpModeError as e:
+            raise e
 
         return res
diff --git a/src/services/api/graphql/utils/schema_from_op_mode.py b/src/services/api/graphql/utils/schema_from_op_mode.py
index f990aae52..379d15250 100755
--- a/src/services/api/graphql/utils/schema_from_op_mode.py
+++ b/src/services/api/graphql/utils/schema_from_op_mode.py
@@ -21,7 +21,7 @@
 import os
 import json
 import typing
-from inspect import signature, getmembers, isfunction
+from inspect import signature, getmembers, isfunction, isclass, getmro
 from jinja2 import Template
 
 from vyos.defaults import directories
@@ -35,6 +35,7 @@ SCHEMA_PATH = directories['api_schema']
 DATA_DIR = directories['data']
 
 op_mode_include_file = os.path.join(DATA_DIR, 'op-mode-standardized.json')
+op_mode_error_schema = 'op_mode_error.graphql'
 
 schema_data: dict = {'schema_name': '',
                      'schema_fields': []}
@@ -53,6 +54,7 @@ type {{ schema_name }} {
 
 type {{ schema_name }}Result {
     data: {{ schema_name }}
+    op_mode_error: OpModeError
     success: Boolean!
     errors: [String]
 }
@@ -76,6 +78,7 @@ type {{ schema_name }} {
 
 type {{ schema_name }}Result {
     data: {{ schema_name }}
+    op_mode_error: OpModeError
     success: Boolean!
     errors: [String]
 }
@@ -85,6 +88,21 @@ extend type Mutation {
 }
 """
 
+error_template = """
+interface OpModeError {
+    name: String!
+    message: String!
+    vyos_code: Int!
+}
+{% for name in error_names %}
+type {{ name }} implements OpModeError {
+    name: String!
+    message: String!
+    vyos_code: Int!
+}
+{%- endfor %}
+"""
+
 def _snake_to_pascal_case(name: str) -> str:
     res = ''.join(map(str.title, name.split('_')))
     return res
@@ -136,7 +154,30 @@ def create_schema(func_name: str, base_name: str, func: callable) -> str:
 
     return res
 
+def create_error_schema():
+    from vyos import opmode
+
+    e = Exception
+    err_types = getmembers(opmode, isclass)
+    err_types = [k for k in err_types if issubclass(k[1], e)]
+    # drop base class, to be replaced by interface type. Find the class
+    # programmatically, in case the base class name changes.
+    for i in range(len(err_types)):
+        if err_types[i][1] in getmro(err_types[i-1][1]):
+            del err_types[i]
+            break
+    err_names = [k[0] for k in err_types]
+    error_data = {'error_names': err_names}
+    j2_template = Template(error_template)
+    res = j2_template.render(error_data)
+
+    return res
+
 def generate_op_mode_definitions():
+    out = create_error_schema()
+    with open(f'{SCHEMA_PATH}/{op_mode_error_schema}', 'w') as f:
+        f.write(out)
+
     with open(op_mode_include_file) as f:
         op_mode_files = json.load(f)