feat(gatsby): add cache control headers to serve command

integration-tests/functions/__tests__/__snapshots__/functions-prod.js.snap

@@ -80,6 +80,7 @@ Object {
 
 exports[`production response formats returns json correctly 2`] = `
 Object {
+  "cache-control": "public, max-age=0, must-revalidate",
   "connection": "close",
   "content-length": "16",
   "content-type": "application/json; charset=utf-8",
@@ -92,6 +93,7 @@ exports[`production response formats returns text correctly 1`] = `"I am typescr
 
 exports[`production response formats returns text correctly 2`] = `
 Object {
+  "cache-control": "public, max-age=0, must-revalidate",
   "connection": "close",
   "content-length": "15",
   "content-type": "text/html; charset=utf-8",

packages/gatsby/src/commands/serve.ts

@@ -8,6 +8,7 @@ import { match as reachMatch } from "@gatsbyjs/reach-router"
 import onExit from "signal-exit"
 import report from "gatsby-cli/lib/reporter"
 import telemetry from "gatsby-telemetry"
+import { isMatch, Options as MicroMatchOptions } from "micromatch"
 
 import { detectPortInUseAndPrompt } from "../utils/detect-port-in-use-and-prompt"
 import { getConfigFile } from "../bootstrap/get-config-file"
@@ -98,6 +99,36 @@ const matchPathRouter =
     return next()
   }
 
+const setCacheHeaders = (
+  req: express.Request,
+  res: express.Response,
+  next: express.NextFunction
+): void => {
+  function match(
+    pattern: string | ReadonlyArray<string>,
+    options?: MicroMatchOptions
+  ): boolean {
+    return isMatch(req.path, pattern, options)
+  }
+
+  if (req.method !== `GET`) {
+    next()
+    return
+  }
+
+  if ((match(`/static/**`) || match(`/**.+(js|css)`)) && !match(`/sw.js`)) {
+    res.header(`Cache-control`, `public, max-age=31536000, immutable`)
+
+    next()
+    return
+  }
+
+  res.header(`Cache-control`, `public, max-age=0, must-revalidate`)
+
+  next()
+  return
+}
+
 module.exports = async (program: IServeProgram): Promise<void> => {
   telemetry.trackCli(`SERVE_START`)
   telemetry.startBackgroundUpdate()
@@ -132,6 +163,7 @@ module.exports = async (program: IServeProgram): Promise<void> => {
   app.use(telemetry.expressMiddleware(`SERVE`))
 
   router.use(compression())
+  app.use(setCacheHeaders)
 
   router.use(
     configureTrailingSlash(