feat(backend): fail on unknown keys in ACL config file

cmd/karma/tests/testscript/074_acl_extra_fileds.txt

@@ -0,0 +1,36 @@
+# Raises an error if --authorization.acl points to a file that contains unknown keys
+karma.bin-should-fail --log.format=text --log.config=false --check-config
+! stdout .
+! stderr 'msg="Configuration is valid"'
+stderr 'msg="Reading silence ACL config file acl.yaml"'
+stderr 'msg="Failed to parse silence ACL configuration file \\"acl.yaml\\": yaml: unmarshal errors:\\n  line 6: field nameFoo not found in type config.SilenceFilters"'
+
+-- karma.yaml --
+authentication:
+  header:
+    name: "X-User"
+    value_re: "(.+)"
+authorization:
+  groups:
+    - name: admins
+      members:
+        - alice
+        - bob
+    - name: users
+      members:
+        - john
+  acl:
+    silences: acl.yaml
+alertmanager:
+  servers:
+    - name: default
+      uri: https://localhost:9093
+
+-- acl.yaml --
+rules:
+  - action: block
+    reason: prod cluster cannot be silenced
+    scope:
+      filters:
+        - nameFoo: cluster
+          value: prod

internal/config/acl.go

@@ -52,7 +52,7 @@ func ReadSilenceACLConfig(path string) (*silencesACLSchema, error) {
 		return nil, fmt.Errorf("Failed to load silence ACL configuration file %q: %v", path, err)
 	}
 
-	err = yaml.Unmarshal(f, &cfg)
+	err = yaml.UnmarshalStrict(f, &cfg)
 	if err != nil {
 		return nil, fmt.Errorf("Failed to parse silence ACL configuration file %q: %v", path, err)
 	}