build(docs-infra): add new angular.io build configuration for release-candidates (#39470)

This commit adds a new build configuration/deployment mode (`rc`) for
deploying release-candidate versions to angular.io.

This is part of the work needed to prepare angular.io for our
[new versioning/branching process][1] (also tracked in #39366).

[1]: https://docs.google.com/document/d/197kVillDwx-RZtSVOBtPb4BBIAw0E9RT3q3v6DZkykU

PR Close #39470

aio/angular.json

@@ -81,6 +81,15 @@
               ],
               "serviceWorker": true
             },
+            "rc": {
+              "fileReplacements": [
+                {
+                  "replace": "src/environments/environment.ts",
+                  "with": "src/environments/environment.rc.ts"
+                }
+              ],
+              "serviceWorker": true
+            },
             "stable": {
               "fileReplacements": [
                 {
@@ -116,6 +125,9 @@
             "next": {
               "browserTarget": "site:build:next"
             },
+            "rc": {
+              "browserTarget": "site:build:rc"
+            },
             "stable": {
               "browserTarget": "site:build:stable"
             },

aio/src/app/app.component.spec.ts

@@ -835,6 +835,7 @@ describe('AppComponent', () => {
       const redirectionPerMode: {[mode: string]: boolean} = {
         archive: true,
         next: false,
+        rc: false,
         stable: false,
       };
 

aio/src/app/app.component.ts

@@ -152,6 +152,7 @@ export class AppComponent implements OnInit {
       // TODO(pbd): consider whether we can lookup the stable and next versions from the internet
       const computedVersions: NavigationNode[] = [
         { title: 'next', url: 'https://next.angular.io/' },
+        { title: 'rc', url: 'https://rc.angular.io/' },
         { title: 'stable', url: 'https://angular.io/' },
       ];
       if (this.deployment.mode === 'archive') {

aio/src/environments/environment.archive.ts

@@ -1,6 +1,6 @@
-// This is for archived sites, which are hosted at https://vX.angular.io, where X is the major Angular version.
+// This is for archived sites, which are hosted at https://vX.angular.io/, where X is the major Angular version.
 export const environment = {
   gaId: 'UA-8594346-15', // Production id (since it is linked from the main site)
   production: true,
-  mode: 'archive'
+  mode: 'archive',
 };

aio/src/environments/environment.next.ts

@@ -1,6 +1,6 @@
-// This is for the staging site, which is hosted at https://next.angular.io (and https://aio-staging.firebaseapp.org)
+// This is for the staging site, which is hosted at https://next.angular.io/.
 export const environment = {
   gaId: 'UA-8594346-15', // Production id (since it is linked from the main site)
   production: true,
-  mode: 'next'
+  mode: 'next',
 };

aio/src/environments/environment.rc.ts

@@ -0,0 +1,6 @@
+// This is for the release-candidate site, which is hosted at https://rc.angular.io/.
+export const environment = {
+  gaId: 'UA-8594346-15', // Production id (since it is linked from the main site)
+  production: true,
+  mode: 'rc',
+};

aio/src/environments/environment.stable.ts

@@ -1,6 +1,6 @@
-// This is for the production site, which is hosted at https://angular.io
+// This is for the production site, which is hosted at https://angular.io/.
 export const environment = {
   gaId: 'UA-8594346-15', // Production id
   production: true,
-  mode: 'stable'
+  mode: 'stable',
 };

aio/src/environments/environment.ts

@@ -1,11 +1,11 @@
 // The file contents for the current environment will overwrite these during build.
 // The build system defaults to the dev environment which uses `environment.ts`, but if you do
-// `ng build --env=prod` then `environment.prod.ts` will be used instead.
-// The list of which env maps to which file can be found in `angular-cli.json`.
+// `ng build --configuration=<foo>` then `environment.<foo>.ts` will be used instead.
+// The list of which configurations maps to which file can be found in `angular.json`.
 
 
 export const environment = {
   gaId: 'UA-8594346-26', // Development id
   production: false,
-  mode: 'stable'
+  mode: 'stable',
 };

aio/src/extra-files/rc/robots.txt

@@ -0,0 +1,3 @@
+# Disallow all URLs (see http://www.robotstxt.org/robotstxt.html)
+User-agent: *
+Disallow: /

aio/src/styles/2-modules/_deploy-theme.scss

@@ -5,3 +5,7 @@ aio-shell.mode-archive {
 aio-shell.mode-next {
   @include deployTheme(#DD0031, #C3002F);
 }
+
+aio-shell.mode-rc {
+  @include deployTheme(#DDA302, #C3A300);
+}