Added a hook for the authentication header

Author: Aaron Aichlmayr

.gitignore

@@ -37,3 +37,5 @@ package.tgz
 !/packages/yarnpkg-pnp/lib/hook.js
 
 /vscode-case-study
+
+.idea

.yarn/versions/c743d681.yml

@@ -0,0 +1,8 @@
+releases:
+  "@yarnpkg/plugin-npm": minor
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/cli"
+  - "@yarnpkg/core"

packages/plugin-npm/sources/Hooks.ts

@@ -0,0 +1,8 @@
+import {Configuration, Ident} from "@yarnpkg/core";
+
+export type Hooks = {
+  getNpmAuthenticationHeader?: (currentHeader: string | undefined, registry: string, {
+    configuration,
+    ident,
+  }: { configuration: Configuration, ident?: Ident }) => Promise<string | undefined>
+};

packages/plugin-npm/sources/index.ts

@@ -1,5 +1,6 @@
 import {Plugin, SettingsType, miscUtils} from '@yarnpkg/core';
 
+import {Hooks}                           from './Hooks';
 import {NpmHttpFetcher}                  from './NpmHttpFetcher';
 import {NpmRemapResolver}                from './NpmRemapResolver';
 import {NpmSemverFetcher}                from './NpmSemverFetcher';
@@ -12,6 +13,7 @@ import * as npmPublishUtils              from './npmPublishUtils';
 export {npmConfigUtils};
 export {npmHttpUtils};
 export {npmPublishUtils};
+export type {Hooks};
 
 const authSettings = {
   npmAlwaysAuth: {

packages/plugin-npm/sources/npmConfigUtils.ts

@@ -5,6 +5,7 @@ export enum RegistryType {
   PUBLISH_REGISTRY = `npmPublishRegistry`,
 }
 
+
 export interface MapLike {
   get(key: string): any;
 }

packages/plugin-npm/sources/npmHttpUtils.ts

@@ -56,7 +56,7 @@ export async function get(path: string, {configuration, headers, ident, authType
   if (typeof registry !== `string`)
     throw new Error(`Assertion failed: The registry should be a string`);
 
-  const auth = getAuthenticationHeader(registry, {authType, configuration, ident});
+  const auth = await getAuthenticationHeader(registry, {authType, configuration, ident});
   if (auth)
     headers = {...headers, authorization: auth};
 
@@ -83,7 +83,7 @@ export async function post(path: string, body: httpUtils.Body, {attemptedAs, con
   if (typeof registry !== `string`)
     throw new Error(`Assertion failed: The registry should be a string`);
 
-  const auth = getAuthenticationHeader(registry, {authType, configuration, ident});
+  const auth = await getAuthenticationHeader(registry, {authType, configuration, ident});
   if (auth)
     headers = {...headers, authorization: auth};
 
@@ -117,7 +117,7 @@ export async function put(path: string, body: httpUtils.Body, {attemptedAs, conf
   if (typeof registry !== `string`)
     throw new Error(`Assertion failed: The registry should be a string`);
 
-  const auth = getAuthenticationHeader(registry, {authType, configuration, ident});
+  const auth = await getAuthenticationHeader(registry, {authType, configuration, ident});
   if (auth)
     headers = {...headers, authorization: auth};
 
@@ -151,7 +151,7 @@ export async function del(path: string, {attemptedAs, configuration, headers, id
   if (typeof registry !== `string`)
     throw new Error(`Assertion failed: The registry should be a string`);
 
-  const auth = getAuthenticationHeader(registry, {authType, configuration, ident});
+  const auth = await getAuthenticationHeader(registry, {authType, configuration, ident});
   if (auth)
     headers = {...headers, authorization: auth};
 
@@ -178,13 +178,21 @@ export async function del(path: string, {attemptedAs, configuration, headers, id
   }
 }
 
-function getAuthenticationHeader(registry: string, {authType = AuthType.CONFIGURATION, configuration, ident}: {authType?: AuthType, configuration: Configuration, ident: RegistryOptions['ident']}) {
+async function getAuthenticationHeader(registry: string, {authType = AuthType.CONFIGURATION, configuration, ident}: {authType?: AuthType, configuration: Configuration, ident: RegistryOptions['ident']}) {
   const effectiveConfiguration = npmConfigUtils.getAuthConfiguration(registry, {configuration, ident});
   const mustAuthenticate = shouldAuthenticate(effectiveConfiguration, authType);
 
   if (!mustAuthenticate)
     return null;
 
+  const header = await configuration.reduceHook(hooks => {
+    return hooks.getNpmAuthenticationHeader;
+  }, undefined, registry, {configuration, ident});
+
+  if (header)
+    return header;
+
+
   if (effectiveConfiguration.get(`npmAuthToken`))
     return `Bearer ${effectiveConfiguration.get(`npmAuthToken`)}`;
   if (effectiveConfiguration.get(`npmAuthIdent`))