scaffolder: add conditional rules

Signed-off-by: Vincenzo Scamporlino <vincenzos@spotify.com>

plugins/scaffolder-backend/src/service/conditionExports.ts

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2022 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { RESOURCE_TYPE_SCAFFOLDER_TEMPLATE } from '@backstage/plugin-scaffolder-common';
+import { createConditionExports } from '@backstage/plugin-permission-node';
+import { scaffolderRules } from './rules';
+import {
+  AllOfCriteria,
+  ConditionalPolicyDecision,
+  PermissionCondition,
+  PermissionRuleParams,
+  ResourcePermission,
+} from '@backstage/plugin-permission-common';
+
+const { conditions: scaffolderConditions, createConditionalDecision } =
+  createConditionExports({
+    pluginId: 'scaffolder',
+    resourceType: RESOURCE_TYPE_SCAFFOLDER_TEMPLATE,
+    rules: scaffolderRules,
+  });
+
+export { scaffolderConditions };
+
+export function createScaffolderConditionalDecision(
+  permission: ResourcePermission<typeof RESOURCE_TYPE_SCAFFOLDER_TEMPLATE>,
+  conditions: AllOfCriteria<
+    PermissionCondition<
+      typeof RESOURCE_TYPE_SCAFFOLDER_TEMPLATE,
+      PermissionRuleParams
+    >
+  >['allOf'],
+): ConditionalPolicyDecision {
+  return createConditionalDecision(permission, { allOf: conditions });
+}

plugins/scaffolder-backend/src/service/rules.ts

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2022 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { makeCreatePermissionRule } from '@backstage/plugin-permission-node';
+import {
+  RESOURCE_TYPE_SCAFFOLDER_TEMPLATE,
+  TemplateEntityV1beta3,
+} from '@backstage/plugin-scaffolder-common';
+import { z } from 'zod';
+
+import get from 'lodash/get';
+import unset from 'lodash/unset';
+import { TemplateTransform } from './helpers';
+import {
+  SecureTemplater,
+  SecureTemplateRenderer,
+} from '../lib/templating/SecureTemplater';
+
+export const createScaffolderPermissionRule = makeCreatePermissionRule<
+  TemplateEntityV1beta3,
+  TemplateTransform,
+  typeof RESOURCE_TYPE_SCAFFOLDER_TEMPLATE
+>();
+
+let render: SecureTemplateRenderer;
+
+export const allowCapabilities = createScaffolderPermissionRule({
+  name: 'ALLOW_CAPABILITIES',
+  resourceType: RESOURCE_TYPE_SCAFFOLDER_TEMPLATE,
+  description: 'Allow capabilities based on permissions',
+  paramsSchema: z.object({
+    capabilities: z.array(z.string()),
+    templateRef: z.string().optional(),
+  }),
+  apply: () => true,
+  toQuery:
+    ({ capabilities }) =>
+    template => {
+      const capabilitiesObj = capabilities.reduce((acc, c) => {
+        acc[c] = true;
+        return acc;
+      }, {} as Record<string, boolean>);
+
+      const parametersPath = ['spec', 'parameters'];
+      const capabilitiesKey = 'backstage:capabilities';
+
+      if (Array.isArray(template.spec.parameters)) {
+        template.spec.parameters.forEach((parameter, index) => {
+          const parameterPath = [...parametersPath, index.toString()];
+          stripParams(parameterPath);
+          if (parameter.properties) {
+            Object.keys(parameter.properties).forEach(p => {
+              if (stripParams([...parameterPath, 'properties', p])) {
+                const requiredProperties = get(template, [
+                  ...parameterPath,
+                  'required',
+                ]);
+                if (Array.isArray(requiredProperties)) {
+                  requiredProperties.splice(requiredProperties.indexOf(p), 1);
+                }
+              }
+            });
+          }
+        });
+      } else {
+        stripParams(parametersPath);
+      }
+
+      template.spec.steps.forEach((_p, index) =>
+        stripParams(['spec', 'steps', index.toString()]),
+      );
+
+      function stripParams(path: string[]) {
+        const jsonObject = get(template, path);
+
+        if (
+          typeof jsonObject[capabilitiesKey] === 'string' &&
+          render(jsonObject[capabilitiesKey], {
+            capabilities: capabilitiesObj,
+          }) !== 'true'
+        ) {
+          const parent = get(template, [...path].splice(0, path.length - 1));
+          if (Array.isArray(parent)) {
+            parent.splice(parent.indexOf(jsonObject), 1);
+          } else {
+            unset(template, path);
+          }
+
+          return path[path.length - 1];
+        }
+        return undefined;
+      }
+
+      return template;
+    },
+});
+
+SecureTemplater.loadRenderer().then(r => (render = r));
+
+export const scaffolderRules = { allowCapabilities };