feat(v2): blog + docs multi-instance plugins (#3204)

* stable createData namespacing + second-blog dogfooding

* Docs: support multi-instance + make community docs a separate instance

* tests: add 2nd docs instance to versioned site

* fix docs version cli tests

* fix docs versioning cli

* typo

* team: add link to my site

* better extendCli integration

* fix metadata tests

* tests for versioned site with second docs instance

* move some validation code to utils-validation

* fix missing dependency

* fix bad compiled output due to importing constants in ./client folder

* make docs tests easier to maintain

* refactors

* prevent lodash imports in client bundle

* redirect old community docs to new urls

packages/docusaurus-utils-validation/src/validationUtils.ts

@@ -0,0 +1,85 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import * as Joi from '@hapi/joi';
+import chalk from 'chalk';
+import {PluginIdSchema} from './validationSchemas';
+
+// TODO temporary escape hatch for alpha-60: to be removed soon
+// Our validation schemas might be buggy at first
+// will permit users to bypass validation until we fix all validation errors
+// see for example: https://github.com/facebook/docusaurus/pull/3120
+// Undocumented on purpose, as we don't want users to keep using it over time
+// Maybe we'll make this escape hatch official some day, with a better api?
+export const isValidationDisabledEscapeHatch =
+  process.env.DISABLE_DOCUSAURUS_VALIDATION === 'true';
+
+if (isValidationDisabledEscapeHatch) {
+  console.error(
+    chalk.red(
+      'You should avoid using DISABLE_DOCUSAURUS_VALIDATION escape hatch, this will be removed',
+    ),
+  );
+}
+
+export const logValidationBugReportHint = () => {
+  console.log(
+    `\n${chalk.red('A validation error occured.')}${chalk.cyanBright(
+      '\nThe validation system was added recently to Docusaurus as an attempt to avoid user configuration errors.' +
+        '\nWe may have made some mistakes.' +
+        '\nIf you think your configuration is valid and should keep working, please open a bug report.',
+    )}\n`,
+  );
+};
+
+export function normalizePluginOptions<T extends {id?: string}>(
+  schema: Joi.ObjectSchema<T>,
+  options: unknown,
+) {
+  // All plugins can be provided an "id" option (multi-instance support)
+  // we add schema validation automatically
+  const finalSchema = schema.append({
+    id: PluginIdSchema,
+  });
+  const {error, value} = finalSchema.validate(options, {
+    convert: false,
+  });
+  if (error) {
+    logValidationBugReportHint();
+    if (isValidationDisabledEscapeHatch) {
+      console.error(error);
+      return options;
+    } else {
+      throw error;
+    }
+  }
+  return value;
+}
+
+export function normalizeThemeConfig<T>(
+  schema: Joi.ObjectSchema<T>,
+  themeConfig: unknown,
+) {
+  // A theme should only validate his "slice" of the full themeConfig,
+  // not the whole object, so we allow unknown attributes
+  // otherwise one theme would fail validating the data of another theme
+  const finalSchema = schema.unknown();
+
+  const {error, value} = finalSchema.validate(themeConfig, {
+    convert: false,
+  });
+
+  if (error) {
+    logValidationBugReportHint();
+    if (isValidationDisabledEscapeHatch) {
+      console.error(error);
+      return themeConfig;
+    } else {
+      throw error;
+    }
+  }
+  return value;
+}