feat(gatsby-plugin-offline): Allow appending custom scripts to sw.js

packages/gatsby-plugin-offline/README.md

@@ -19,44 +19,127 @@ in the service worker.
 plugins: [`gatsby-plugin-offline`]
 ```
 
-## Overriding options
+## Available options
 
-When adding this plugin to your `gatsby-config.js`, you can pass in options (via the `options` key) to
-override the default [Workbox](https://developers.google.com/web/tools/workbox/modules/workbox-build) config.
+As of `gatsby-plugin-offline` 3.0.0, the following options are available:
 
-The default config is as follows. Warning: You can break the offline support by
-changing these options, so tread carefully.
+- `appendScript` lets you specify a file to be appended at the end of the generated service worker (`sw.js`). For example:
+
+  ```javascript:title=gatsby-config.js
+  plugins: [
+    {
+      resolve: `gatsby-plugin-offline`,
+      options: {
+        appendScript: `src/custom-sw-code.js`,
+      },
+    },
+  ]
+  ```
+
+  ```javascript:title=src/custom-sw-code.js
+  // show a notification after 15 seconds (the notification
+  // permission must be granted first)
+  setTimeout(() => {
+    self.registration.showNotification("Hello, world!")
+  }, 15000)
+
+  // register a custom navigation route
+  const customRoute = new workbox.routing.NavigationRoute(({ event }) => {
+    // ...
+  })
+  workbox.routing.registerRoute(customRoute)
+  ```
+
+- `workboxConfig` allows you to override the default Workbox options - see [Overriding Workbox configuration](#overriding-workbox-configuration). For example:
+
+  ```javascript:title=gatsby-config.js
+  plugins: [
+    {
+      resolve: `gatsby-plugin-offline`,
+      options: {
+        workboxConfig: {
+          importWorkboxFrom: `cdn`,
+        },
+      },
+    },
+  ]
+  ```
+
+## Upgrading from 2.x
+
+To upgrade from 2.x to 3.x, move any existing options into the `workboxConfig` option. If you haven't specified any options, you have nothing to do.
+
+For example, here is a 2.x config:
+
+```javascript
+plugins: [
+  {
+    resolve: `gatsby-plugin-offline`,
+    options: {
+      importWorkboxFrom: `cdn`,
+    },
+  },
+]
+```
+
+Here is the equivalent 3.x config:
+
+```javascript
+plugins: [
+  {
+    resolve: `gatsby-plugin-offline`,
+    options: {
+      workboxConfig: {
+        importWorkboxFrom: `cdn`,
+      },
+    },
+  },
+]
+```
+
+In version 3, Workbox is also upgraded to version 4 so you may need to update your `workboxConfig` if any of those changes apply to you. Please see the [docs on Google Developers](https://developers.google.com/web/tools/workbox/guides/migrations/migrate-from-v3) for more information.
+
+## Overriding Workbox configuration
+
+When adding this plugin to your `gatsby-config.js`, you can use the option `workboxConfig` to override the default Workbox config. To see the full list of options, see [this article on Google Developers](https://developers.google.com/web/tools/workbox/modules/workbox-build#full_generatesw_config).
+
+The default `workboxConfig` is as follows. Note that some of these options are configured automatically, e.g. `globPatterns`. If you're not sure about what all of these options mean, it's best to leave them as-is - otherwise, you may end up causing errors on your site, causing old files to be remain cached, or even breaking offline support.
 
 ```javascript
 const options = {
   importWorkboxFrom: `local`,
   globDirectory: rootDir,
   globPatterns,
-  modifyUrlPrefix: {
+  modifyURLPrefix: {
     // If `pathPrefix` is configured by user, we should replace
     // the default prefix with `pathPrefix`.
     "/": `${pathPrefix}/`,
   },
   cacheId: `gatsby-plugin-offline`,
   // Don't cache-bust JS or CSS files, and anything in the static directory,
   // since these files have unique URLs and their contents will never change
-  dontCacheBustUrlsMatching: /(\.js$|\.css$|static\/)/,
+  dontCacheBustURLsMatching: /(\.js$|\.css$|static\/)/,
   runtimeCaching: [
     {
       // Use cacheFirst since these don't need to be revalidated (same RegExp
       // and same reason as above)
       urlPattern: /(\.js$|\.css$|static\/)/,
-      handler: `cacheFirst`,
+      handler: `CacheFirst`,
+    },
+    {
+      // page-data.json files are not content hashed
+      urlPattern: /^https?:.*\page-data\/.*\/page-data\.json/,
+      handler: `NetworkFirst`,
     },
     {
       // Add runtime caching of various other page resources
       urlPattern: /^https?:.*\.(png|jpg|jpeg|webp|svg|gif|tiff|js|woff|woff2|json|css)$/,
-      handler: `staleWhileRevalidate`,
+      handler: `StaleWhileRevalidate`,
     },
     {
       // Google Fonts CSS (doesn't end in .css so we need to specify it)
       urlPattern: /^https?:\/\/fonts\.googleapis\.com\/css/,
-      handler: `staleWhileRevalidate`,
+      handler: `StaleWhileRevalidate`,
     },
   ],
   skipWaiting: true,

packages/gatsby-plugin-offline/package.json

@@ -12,7 +12,7 @@
     "idb-keyval": "^3.2.0",
     "lodash": "^4.17.15",
     "slash": "^3.0.0",
-    "workbox-build": "^3.6.3"
+    "workbox-build": "^4.3.1"
   },
   "devDependencies": {
     "@babel/cli": "^7.5.5",

packages/gatsby-plugin-offline/src/__tests__/fixtures/custom-sw-code.js

@@ -0,0 +1 @@
+console.log(`Hello, world!`)

packages/gatsby-plugin-offline/src/__tests__/gatsby-node.js

@@ -0,0 +1,59 @@
+const { onPostBuild } = require(`../gatsby-node`)
+const fs = require(`fs`)
+
+jest.mock(`fs`)
+jest.mock(`../get-resources-from-html`, () => () => [])
+
+let swText = ``
+
+jest.mock(`workbox-build`, () => {
+  return {
+    generateSW() {
+      return Promise.resolve({ count: 1, size: 1, warnings: [] })
+    },
+  }
+})
+
+describe(`onPostBuild`, () => {
+  const componentChunkName = `chunkName`
+  const chunks = [`chunk1`, `chunk2`]
+
+  // Mock webpack.stats.json
+  const stats = {
+    assetsByChunkName: {
+      [componentChunkName]: chunks,
+    },
+  }
+
+  // Mock out filesystem functions
+  fs.readFileSync.mockImplementation(file => {
+    if (file === `${process.cwd()}/public/webpack.stats.json`) {
+      return JSON.stringify(stats)
+    } else if (file === `public/sw.js`) {
+      return swText
+    } else if (file.match(/\/sw-append\.js/)) {
+      return ``
+    } else {
+      return jest.requireActual(`fs`).readFileSync(file)
+    }
+  })
+
+  fs.appendFileSync.mockImplementation((file, text) => {
+    swText += text
+  })
+
+  fs.createReadStream.mockImplementation(() => {
+    return { pipe() {} }
+  })
+
+  fs.createWriteStream.mockImplementation(() => {})
+
+  it(`appends to sw.js`, async () => {
+    await onPostBuild(
+      { pathPrefix: `` },
+      { appendScript: `${__dirname}/fixtures/custom-sw-code.js` }
+    )
+
+    expect(swText).toContain(`console.log(\`Hello, world!\`)`)
+  })
+})

packages/gatsby-plugin-offline/src/gatsby-node.js

@@ -70,47 +70,46 @@ exports.onPostBuild = (args, pluginOptions) => {
     importWorkboxFrom: `local`,
     globDirectory: rootDir,
     globPatterns,
-    modifyUrlPrefix: {
+    modifyURLPrefix: {
       // If `pathPrefix` is configured by user, we should replace
       // the default prefix with `pathPrefix`.
       "/": `${pathPrefix}/`,
     },
     cacheId: `gatsby-plugin-offline`,
     // Don't cache-bust JS or CSS files, and anything in the static directory,
     // since these files have unique URLs and their contents will never change
-    dontCacheBustUrlsMatching: /(\.js$|\.css$|static\/)/,
+    dontCacheBustURLsMatching: /(\.js$|\.css$|static\/)/,
     runtimeCaching: [
       {
         // Use cacheFirst since these don't need to be revalidated (same RegExp
         // and same reason as above)
         urlPattern: /(\.js$|\.css$|static\/)/,
-        handler: `cacheFirst`,
+        handler: `CacheFirst`,
       },
       {
         // page-data.json files are not content hashed
         urlPattern: /^https?:.*\page-data\/.*\/page-data\.json/,
-        handler: `networkFirst`,
+        handler: `NetworkFirst`,
       },
       {
         // Add runtime caching of various other page resources
         urlPattern: /^https?:.*\.(png|jpg|jpeg|webp|svg|gif|tiff|js|woff|woff2|json|css)$/,
-        handler: `staleWhileRevalidate`,
+        handler: `StaleWhileRevalidate`,
       },
       {
         // Google Fonts CSS (doesn't end in .css so we need to specify it)
         urlPattern: /^https?:\/\/fonts\.googleapis\.com\/css/,
-        handler: `staleWhileRevalidate`,
+        handler: `StaleWhileRevalidate`,
       },
     ],
     skipWaiting: true,
     clientsClaim: true,
   }
 
-  // pluginOptions.plugins is assigned automatically when the user hasn't
-  // specified custom options - Workbox throws an error with unsupported
-  // parameters, so delete it.
-  delete pluginOptions.plugins
-  const combinedOptions = _.defaults(pluginOptions, options)
+  const combinedOptions = {
+    ...options,
+    ...pluginOptions.workboxConfig,
+  }
 
   const idbKeyvalFile = `idb-keyval-iife.min.js`
   const idbKeyvalSource = require.resolve(`idb-keyval/dist/${idbKeyvalFile}`)
@@ -129,6 +128,17 @@ exports.onPostBuild = (args, pluginOptions) => {
         .replace(/%appFile%/g, appFile)
 
       fs.appendFileSync(`public/sw.js`, `\n` + swAppend)
+
+      if (pluginOptions.appendScript) {
+        let userAppend
+        try {
+          userAppend = fs.readFileSync(pluginOptions.appendScript, `utf8`)
+        } catch (e) {
+          throw new Error(`Couldn't find the specified offline inject script`)
+        }
+        fs.appendFileSync(`public/sw.js`, `\n` + userAppend)
+      }
+
       console.log(
         `Generated ${swDest}, which will precache ${count} files, totaling ${size} bytes.`
       )

packages/gatsby-plugin-offline/src/sw-append.js

@@ -25,7 +25,8 @@ const navigationRoute = new NavigationRoute(async ({ event }) => {
   }
 
   const offlineShell = `%pathPrefix%/offline-plugin-app-shell-fallback/index.html`
-  return await caches.match(offlineShell)
+  const offlineShellWithKey = workbox.precaching.getCacheKeyForURL(offlineShell)
+  return await caches.match(offlineShellWithKey)
 })
 
 workbox.routing.registerRoute(navigationRoute)