Add option in SSG for outputting SRI hashes as JSON

[Bwc9876]

Hey there, this project seems super handy!

One thing is that in an SSR context where the Astro output is being used by a framework written in another language (Django, Flask, Rocket, etc) it may be handy to have an option to output SRI hashes of a statically generated site to JSON instead of a JS module.

[castarco]

Hi @Bwc9876, that sounds like a good idea 😃. I have some doubts about your proposal, though.

How do you expect it to work? In my mind I have something quite simple, just having an exact equivalent of the "hashes module" but in JSON format.

So, if today we have sri.hashesModule, we would also have the option sri.hashesJson (or something similar, I'd have to think about its name).

[Bwc9876]

Yeah I was thinking the same thing, another option to specify a path to output the JSON to like sri.hashesJson would work.

[rgant]

This would be quite useful to have. JSON is pretty universal.

Would save me from having to implement a build process to rename the .mjs file into TypeScript, or one to convert it into JSON like so:

#!/usr/bin/env -S node --experimental-strip-types --disable-warning=ExperimentalWarning
import { writeFileSync } from 'node:fs'; // eslint-disable-line import-x/no-nodejs-modules -- This is a node script
import { resolve } from 'node:path'; // eslint-disable-line unicorn/import-style, import-x/no-nodejs-modules -- This is a node script

import { perResourceSriHashes } from '../generated/sriHashes.mjs';

/** Enable JSON pretty printing for clearer diffs */
const INDENT = 2;
const NOOP_REPLACER = undefined;
// writeFileSync is happiest with an absolute file path.
const JSON_FILE = resolve(import.meta.dirname, '..', 'generated', 'sriHashes.json');

const getHashes = (key: 'scripts' | 'styles'): string => {
  const hashes = Object.values(perResourceSriHashes[key]);
  if (hashes.length > 0) {
    return `'${hashes.join("' '")}'`;
  }

  return '';
};

const sriHashes = {
  scripts: getHashes('scripts'),
  styles: getHashes('styles'),
};

const jsonStr = JSON.stringify(sriHashes, NOOP_REPLACER, INDENT);
writeFileSync(JSON_FILE, jsonStr);