Make the local cache opt-in (rather than opt-out)

packages/gatsby/content/advanced/lexicon.md

@@ -67,6 +67,14 @@ See also: the [`Linker` interface](https://github.com/yarnpkg/berry/blob/master/
 
 See also: the [`Installer` interface](https://github.com/yarnpkg/berry/blob/master/packages/yarnpkg-core/sources/Installer.ts#L18)
 
+### Local Cache
+
+The local cache is a way to protect against registries going down by keeping a cache of your packages within your very project (often checked-in within the repository). While not always practical (it causes the repository size to grow, although we have ways to mitigate it significantly), it presents various interesting properties:
+
+- It doesn't require additional infrastructure, such as a [Verdaccio proxy](https://verdaccio.org/)
+- The install fetch step is as fast as it can be, with no data transfer at all
+- It lets you reach [zero-installs](https://yarnpkg.com/features/zero-installs) if you also use the PnP linker
+
 ### Locator
 
 A locator is a combination of a package name (for example `lodash`) and a package <abbr>reference</abbr> (for example `1.2.3`). Locators are used to identify a single unique package (interestingly, all valid locators also are valid <abbr>descriptors</abbr>).

packages/plugin-npm/sources/NpmHttpFetcher.ts

@@ -1,6 +1,6 @@
 import {Fetcher, FetchOptions, MinimalFetchOptions} from '@yarnpkg/core';
 import {Locator}                                    from '@yarnpkg/core';
-import {structUtils, tgzUtils}                      from '@yarnpkg/core';
+import {formatUtils, structUtils, tgzUtils}         from '@yarnpkg/core';
 import semver                                       from 'semver';
 
 import {PROTOCOL}                                   from './constants';
@@ -50,6 +50,7 @@ export class NpmHttpFetcher implements Fetcher {
       throw new Error(`Assertion failed: The archiveUrl querystring parameter should have been available`);
 
     const sourceBuffer = await npmHttpUtils.get(params.__archiveUrl, {
+      customErrorMessage: npmHttpUtils.customPackageError,
       configuration: opts.project.configuration,
       ident: locator,
     });

packages/plugin-npm/sources/NpmSemverFetcher.ts

@@ -50,6 +50,7 @@ export class NpmSemverFetcher implements Fetcher {
     let sourceBuffer;
     try {
       sourceBuffer = await npmHttpUtils.get(NpmSemverFetcher.getLocatorUrl(locator), {
+        customErrorMessage: npmHttpUtils.customPackageError,
         configuration: opts.project.configuration,
         ident: locator,
       });
@@ -58,6 +59,7 @@ export class NpmSemverFetcher implements Fetcher {
       // OK: https://registry.yarnpkg.com/@emotion%2fbabel-preset-css-prop/-/babel-preset-css-prop-10.0.7.tgz
       // KO: https://registry.yarnpkg.com/@xtuc%2fieee754/-/ieee754-1.2.0.tgz
       sourceBuffer = await npmHttpUtils.get(NpmSemverFetcher.getLocatorUrl(locator).replace(/%2f/g, `/`), {
+        customErrorMessage: npmHttpUtils.customPackageError,
         configuration: opts.project.configuration,
         ident: locator,
       });

packages/plugin-npm/sources/NpmSemverResolver.ts

@@ -48,6 +48,7 @@ export class NpmSemverResolver implements Resolver {
       throw new Error(`Expected a valid range, got ${descriptor.range.slice(PROTOCOL.length)}`);
 
     const registryData = await npmHttpUtils.get(npmHttpUtils.getIdentUrl(descriptor), {
+      customErrorMessage: npmHttpUtils.customPackageError,
       configuration: opts.project.configuration,
       ident: descriptor,
       jsonResponse: true,
@@ -118,6 +119,7 @@ export class NpmSemverResolver implements Resolver {
       throw new ReportError(MessageName.RESOLVER_NOT_FOUND, `The npm semver resolver got selected, but the version isn't semver`);
 
     const registryData = await npmHttpUtils.get(npmHttpUtils.getIdentUrl(locator), {
+      customErrorMessage: npmHttpUtils.customPackageError,
       configuration: opts.project.configuration,
       ident: locator,
       jsonResponse: true,

packages/plugin-npm/sources/npmHttpUtils.ts

@@ -1,4 +1,4 @@
-import {Configuration, Ident, httpUtils} from '@yarnpkg/core';
+import {Configuration, Ident, formatUtils, httpUtils} from '@yarnpkg/core';
 import {MessageName, ReportError}        from '@yarnpkg/core';
 import {prompt}                          from 'enquirer';
 import {URL}                             from 'url';
@@ -42,8 +42,18 @@ export async function handleInvalidAuthenticationError(error: any, {attemptedAs,
   }
 }
 
-export function customPackageError(error: httpUtils.RequestError) {
-  return error.response?.statusCode === 404 ? `Package not found` : null;
+export function customPackageError(error: httpUtils.RequestError, configuration: Configuration) {
+  const statusCode = error.response?.statusCode;
+  if (!statusCode)
+    return null;
+
+  if (statusCode === 404)
+    return `Package not found`;
+
+  if (statusCode >= 500 && statusCode < 600)
+    return `The registry appears to be down (using a ${formatUtils.applyHyperlink(configuration, `local cache`, `https://yarnpkg.com/advanced/lexicon#local-cache`)} might have protected you against such outages)`;
+
+  return null;
 }
 
 export function getIdentUrl(ident: Ident) {

packages/yarnpkg-core/sources/Configuration.ts

@@ -214,7 +214,7 @@ export const coreDefinitions: {[coreSettingName: string]: SettingsDefinition} =
   enableGlobalCache: {
     description: `If true, the system-wide cache folder will be used regardless of \`cache-folder\``,
     type: SettingsType.BOOLEAN,
-    default: false,
+    default: true,
   },
 
   // Settings related to the output style

packages/yarnpkg-core/sources/httpUtils.ts

@@ -47,14 +47,14 @@ function prettyResponseCode({statusCode, statusMessage}: Response, configuration
   return formatUtils.applyHyperlink(configuration, `${prettyStatusCode}${statusMessage ? ` (${statusMessage})` : ``}`, href);
 }
 
-async function prettyNetworkError(response: Promise<Response<any>>, {configuration, customErrorMessage}: {configuration: Configuration, customErrorMessage?: (err: RequestError) => string | null}) {
+async function prettyNetworkError(response: Promise<Response<any>>, {configuration, customErrorMessage}: {configuration: Configuration, customErrorMessage?: (err: RequestError, configuration: Configuration) => string | null}) {
   try {
     return await response;
   } catch (err) {
     if (err.name !== `HTTPError`)
       throw err;
 
-    let message = customErrorMessage?.(err) ?? err.response.body?.error;
+    let message = customErrorMessage?.(err, configuration) ?? err.response.body?.error;
 
     if (message == null) {
       if (err.message.startsWith(`Response code`)) {
@@ -65,7 +65,7 @@ async function prettyNetworkError(response: Promise<Response<any>>, {configurati
     }
 
     if (err instanceof TimeoutError && err.event === `socket`)
-      message += `(can be increased via ${formatUtils.pretty(configuration, `httpTimeout`, formatUtils.Type.SETTING)})`;
+      message += ` (can be increased via ${formatUtils.pretty(configuration, `httpTimeout`, formatUtils.Type.SETTING)})`;
 
     const networkError = new ReportError(MessageName.NETWORK_ERROR, message, report => {
       if (err.response) {
@@ -166,7 +166,7 @@ export enum Method {
 
 export type Options = {
   configuration: Configuration;
-  customErrorMessage?: (err: RequestError) => string | null;
+  customErrorMessage?: (err: RequestError, configuration: Configuration) => string | null;
   headers?: {[headerName: string]: string};
   jsonRequest?: boolean;
   jsonResponse?: boolean;
@@ -183,9 +183,9 @@ export async function request(target: string | URL, body: Body, {configuration,
   return await executor();
 }
 
-export async function get(target: string, {configuration, jsonResponse, ...rest}: Options) {
+export async function get(target: string, {configuration, jsonResponse, customErrorMessage, ...rest}: Options) {
   let entry = miscUtils.getFactoryWithDefault(cache, target, () => {
-    return prettyNetworkError(request(target, null, {configuration, ...rest}), {configuration}).then(response => {
+    return prettyNetworkError(request(target, null, {configuration, ...rest}), {configuration, customErrorMessage}).then(response => {
       cache.set(target, response.body);
       return response.body;
     });
@@ -202,19 +202,19 @@ export async function get(target: string, {configuration, jsonResponse, ...rest}
 }
 
 export async function put(target: string, body: Body, {customErrorMessage, ...options}: Options): Promise<Buffer> {
-  const response = await prettyNetworkError(request(target, body, {...options, method: Method.PUT}), options);
+  const response = await prettyNetworkError(request(target, body, {...options, method: Method.PUT}), {customErrorMessage, configuration: options.configuration});
 
   return response.body;
 }
 
 export async function post(target: string, body: Body, {customErrorMessage, ...options}: Options): Promise<Buffer> {
-  const response = await prettyNetworkError(request(target, body, {...options, method: Method.POST}), options);
+  const response = await prettyNetworkError(request(target, body, {...options, method: Method.POST}), {customErrorMessage, configuration: options.configuration});
 
   return response.body;
 }
 
 export async function del(target: string, {customErrorMessage, ...options}: Options): Promise<Buffer> {
-  const response = await prettyNetworkError(request(target, null, {...options, method: Method.DELETE}), options);
+  const response = await prettyNetworkError(request(target, null, {...options, method: Method.DELETE}), {customErrorMessage, configuration: options.configuration});
 
   return response.body;
 }