manifest-plugin.js

var fs = require("fs");
var fse = require("fs-extra");
const crypto = require("crypto");

var DEFAULT_PARAMS = {
    manifestFile: "/rails-app/config/sprockets-manifest.json",
    statsFile: "webpack-stats.json"
};

function WebpackSprocketsRailsManifestPlugin(options) {
    var params = options || {};

    this._manifestFile = params.manifestFile || DEFAULT_PARAMS.manifestFile;
    this._statsFile = params.statsFile || DEFAULT_PARAMS.statsFile;
}

function processFile(outputPath, sprockets, logicalPath, chunkFilename) {
    var chunkPath = outputPath + "/" + chunkFilename;
    var stat = fs.statSync(chunkPath);
    const fileBuffer = fs.readFileSync(chunkPath);
    const hashSum = crypto.createHash('sha256');
    hashSum.update(fileBuffer);
    const hash = hashSum.digest('base64');
    const hexHash = Buffer.from(hash, 'base64').toString('hex');

    sprockets.files[chunkFilename] = {
        "logical_path": logicalPath,
        "mtime": stat.mtime.toISOString(),
        "size": stat.size,
        "digest": hexHash,
        "integrity": "sha256-" + hash
    };
    sprockets.assets[logicalPath] = chunkFilename;
}

WebpackSprocketsRailsManifestPlugin.prototype.apply = function(compiler) {
    var manifestFile = this._manifestFile;
    var statsFile = this._statsFile;
    var sprockets = {
        files: {},
        assets: {}
    };

    compiler.hooks.done.tap("WebpackSprocketsRailsManifestPlugin", function(stats) {
        var statsJson = stats.toJson();
        var chunks = statsJson.chunks;
        var devServer = compiler.options.devServer;
        var outputPath;

        if (devServer && devServer.contentBase) {
            outputPath = devServer.contentBase;
        } else {
            outputPath = compiler.options.output.path;
        }

        var manifestPath = outputPath + "/" + manifestFile;

        chunks.forEach(function(chunk) {
            const logicalName = chunk.names[0];
            chunk.files.forEach(filename => {
                const chunkExtension = filename.split(".").pop();
                processFile(outputPath, sprockets, `${logicalName}.${chunkExtension}`, filename)
            });
            chunk.auxiliaryFiles
                .filter(name => !name.endsWith('.map'))
                .forEach(filename => {
                    const nameParts = filename.split(".");
                    processFile(outputPath, sprockets, `${nameParts[0]}.${nameParts[2]}`, filename)
                });
        });

        fse.mkdirpSync(outputPath);

        // delete files matching glob pattern
        let regex = /\.sprockets-manifest-.*\.json$/
        fs.readdirSync(outputPath)
            .filter(f => regex.test(f))
            .map(f => fs.unlinkSync(outputPath + "/" + f));
        fse.outputFileSync(manifestPath, JSON.stringify(sprockets, null, "  "));
    });
};

module.exports = WebpackSprocketsRailsManifestPlugin;