extracted & published netlify-plugin-cache on NPM: https://github.com/jakejarvis/netlify-plugin-cache

plugins/netlify-plugin-cache/index.js

@@ -1,30 +0,0 @@
-// https://github.com/netlify/build/blob/master/packages/cache-utils/README.md
-
-module.exports = {
-  // try to restore cache before build begins, if it exists
-  onPreBuild: async ({ utils: { cache }, inputs }) => {
-    if (await cache.restore(inputs.paths)) {
-      const files = await cache.list(inputs.paths)
-      console.log(`Successfully restored: ${inputs.paths.join(', ')} ... ${files.length} files in total.`)
-    } else {
-      console.log(`A cache of ${inputs.paths.join(', ')} doesn't exist (yet).`)
-    }
-  },
-
-  // only save/update cache if build was successful
-  onSuccess: async ({ utils: { cache, status }, inputs }) => {
-    if (await cache.save(inputs.paths)) {
-      const files = await cache.list(inputs.paths)
-      console.log(`Successfully cached: ${inputs.paths.join(', ')} ... ${files.length} files in total.`)
-
-      // show success & more detail in deploy summary
-      status.show({
-        title: `${files.length} files cached`,
-        summary: 'These will be restored on the next build! ⚡',
-        text: `${inputs.paths.join(', ')}`,
-      })
-    } else {
-      console.log(`Failed caching ${inputs.paths.join(', ')}. :(`)
-    }
-  },
-}

plugins/netlify-plugin-cache/manifest.yml

@@ -1,5 +0,0 @@
-name: netlify-plugin-cache
-inputs:
-- name: paths
-  description: Array of files and/or directories to cache between builds.
-  required: true