decouple asset hashing from webpack

build/app/asset-hashes.js

@@ -0,0 +1,20 @@
+const path = require('path');
+const fs = require('fs');
+const crypto = require('crypto');
+
+module.exports = () => {
+	const hashes = fs.readdirSync(path.join(process.cwd(), 'public'))
+		.filter(asset => !/(\.map|about\.json|asset-hashes\.json)$/.test(asset))
+		.map(name => {
+			const file = fs.readFileSync(path.join(process.cwd(), 'public', name), 'utf8');
+			const hash = crypto.createHash('sha1').update(file).digest('hex');
+			const hashedName = `${hash.substring(0, 8)}/${name}`;
+			return { name, hashedName };
+		})
+		.reduce((previous, current) => {
+			previous[current.name] = current.hashedName;
+			previous[current.name + '.map'] = current.hashedName + '.map';
+			return previous;
+		}, {});
+	fs.writeFileSync('./public/asset-hashes.json', JSON.stringify(hashes, null, 2), { encoding: 'UTF8' });
+}

build/app/cli.js

@@ -5,6 +5,7 @@ const path = require('path');
 const shellpromise = require('shellpromise');
 const shellpipe = require('./shellpipe');
 const downloadAssets = require('./download-assets');
+const assetHashes = require('./asset-hashes')
 
 const exit = err => {
 	logger.error(err);
@@ -50,6 +51,7 @@ program
 		devAdvice();
 
 		shellpipe(`webpack ${options.production ? '--bail' : '--dev'} --config ${webpackConfPath}`)
+			.then(assetHashes)
 			.then(aboutJson)
 			.then(downloadAssets)
 			.then(() => {

build/app/webpack.js

@@ -4,7 +4,6 @@ const fs = require('fs');
 const join = require('path').join;
 const Wrap = require('../lib/addons/wrap');
 const headCss = require('../lib/head-css')
-const hashedAssets = require('../lib/hashed-assets')
 
 const gitignore = fs.readFileSync(join(process.cwd(), '.gitignore'), 'utf8')
 	.split('\n');
@@ -47,9 +46,9 @@ noGitignoreWildcard();
 // we no longer build a main.js for the app when generating the standard asset variants
 const variants = [
 	// all entry points excluding main.js generated as normal
-	hashedAssets(headCss(nWebpack(Object.assign({}, baseConfig, {
+	headCss(nWebpack(Object.assign({}, baseConfig, {
 		entry: filterEntryKeys(baseConfig.entry, /main\.js$/, true)
-	}))))
+	})))
 ]
 
 // new entry point for main.js declaring external n-ui
@@ -69,7 +68,7 @@ mainJs.plugins.push(
 	)
 );
 
-variants.push(hashedAssets(mainJs));
+variants.push(mainJs);
 
 if (process.env.NEXT_APP_SHELL === 'local') {
 	const nWebpackWarning = `