Support feature worker declaration from gitlab.teklia.com

Closes #1883 (closed)

• Requires tests

arkindex/process/management/commands/update_system_workers.py

+from collections import defaultdict
+
 from django.conf import settings
 from django.core.management.base import BaseCommand, CommandError
 from django.db import transaction
 from django.db.models import Max
-from teklia_toolbox.config import ConfigParser
+from teklia_toolbox.config import ConfigParser, ConfigurationError
 
 from arkindex.process.models import ArkindexFeature, FeatureUsage, Worker, WorkerType, WorkerVersion, WorkerVersionState
 
@@ -17,12 +19,25 @@ def parse_config():
         feature_parser = features_parser.add_subparser(feature.value, allow_extra_keys=False, default={})
         feature_parser.add_option("image", type=str, default=None)
         feature_parser.add_option("command", type=str, default=None)
-        teklia_worker_parser = feature_parser.add_subparser("teklia_worker", allow_extra_keys=False, default={})
+        teklia_worker_parser = feature_parser.add_subparser("teklia_worker", allow_extra_keys=False, default=None)
         teklia_worker_parser.add_option("name", type=str, default=None)
         teklia_worker_parser.add_option("version", type=str, default=None)
         teklia_worker_parser.add_option("slug", type=str, default=None)
 
-    return parser.parse(settings.BASE_DIR / "system_workers.yml")
+    parsed = parser.parse(settings.BASE_DIR / "system_workers.yml")
+
+    errors = defaultdict(list)
+    for feature, config in parsed["features"].items():
+        if config["image"] and config["teklia_worker"]:
+            errors[feature].append("Exactly one of image/command or teklia_parser must be set")
+            continue
+        if (subparser := config["teklia_worker"]) and (None in subparser.values()):
+            errors[feature].append("teklia_parser configuration must define a name, a version and a slug")
+        if (config["command"] and config["image"] is None):
+            errors[feature].append("command argument must be set with the image argument")
+    if errors:
+        raise ConfigurationError(errors)
+    return parsed
 
 
 class Command(BaseCommand):