DON-66 - fix index replacements + favicons

See angular/angular-cli#10881 for
discussion on replacing index files per-environment

Author: NoelLH

angular.json

@@ -39,12 +39,12 @@
                 {
                   "replace": "src/environments/environment.ts",
                   "with": "src/environments/environment.production.ts"
-                },
-                {
-                  "replace": "src/index.html",
-                  "with": "src/index.production.html"
                 }
               ],
+              "index": {
+                "input": "src/index.production.html",
+                "output": "index.html"
+              },
               "optimization": true,
               "outputHashing": "all",
               "sourceMap": false,
@@ -67,12 +67,12 @@
                 {
                   "replace": "src/environments/environment.ts",
                   "with": "src/environments/environment.staging.ts"
-                },
-                {
-                  "replace": "src/index.html",
-                  "with": "src/index.staging.html"
                 }
               ],
+              "index": {
+                "input": "src/index.staging.html",
+                "output": "index.html"
+              },
               "optimization": true,
               "outputHashing": "all",
               "sourceMap": false,
@@ -165,10 +165,6 @@
                 {
                   "replace": "src/environments/environment.ts",
                   "with": "src/environments/environment.production.ts"
-                },
-                {
-                  "replace": "src/index.html",
-                  "with": "src/index.production.html"
                 }
               ]
             },
@@ -177,10 +173,6 @@
                 {
                   "replace": "src/environments/environment.ts",
                   "with": "src/environments/environment.staging.ts"
-                },
-                {
-                  "replace": "src/index.html",
-                  "with": "src/index.staging.html"
                 }
               ]
             }

server.ts

@@ -49,18 +49,26 @@ app.get('/robots.txt', (req, res) => {
 });
 
 // Serve static files requested via /d/ from /browser/d - when deployed S3 serves these up to CloudFront
+app.get('/d/favicon.ico', (req, res) => {
+  res.sendFile(DIST_FOLDER + '/favicon.ico', {
+    maxAge: '7 days', // Don't make the favicon immutable in case we want to update it
+  });
+});
+
 app.use('/d', express.static(DIST_FOLDER, {
-  immutable: true,
-  maxAge: '1y',
+  immutable: true, // Everything in here should be named with an immutable hash
+  maxAge: '1 year',
 }));
 
-// And similar for /assets
 app.use('/assets', express.static(DIST_FOLDER + '/assets', {
-  maxAge: '1d',
+  maxAge: '1 day', // Assets should be served similarly but don't have name-hashes
 }));
 
 // All regular routes use the Universal engine
 app.get('*', (req, res) => {
+  // Note that the file output as `index.html` is actually dynamic. See `index` config keys in `angular.json`.
+  // See https://github.com/angular/angular-cli/issues/10881#issuecomment-530864193 for info on the undocumented use of
+  // this key to work around `fileReplacements` ending index support in Angular 8.
   res.render('index', { req });
 });