matrix-public-archive/server/hydrogen-render/render-hydrogen-to-string.js

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'use strict';
// Server-side render Hydrogen to a string.
//
// We use a `child_process` because we want to be able to exit the process after
// we receive the SSR results. We don't want Hydrogen to keep running after we
// get our initial rendered HTML.
const assert = require('assert');
const RethrownError = require('../lib/errors/rethrown-error');
const RouteTimeoutAbortError = require('../lib/errors/route-timeout-abort-error');
const UserClosedConnectionAbortError = require('../lib/errors/user-closed-connection-abort-error');
const runInChildProcess = require('../child-process-runner/run-in-child-process');
const resolvedRenderHydrogenToStringUnsafeScriptPath = require.resolve(
'./render-hydrogen-to-string-unsafe'
);
// The render should be fast. If it's taking more than 5 seconds, something has
// gone really wrong.
const RENDER_TIMEOUT = 5000;
async function renderHydrogenToString({ renderOptions, abortSignal }) {
assert(renderOptions);
// We expect `config` but we should sanity check that we aren't leaking the access token
// to the client if someone naievely copied the whole `config` object to here.
assert(renderOptions.vmRenderContext.config);
assert(
!renderOptions.vmRenderContext.config.matrixAccessToken,
'We should not be leaking the `config.matrixAccessToken` to the Hydrogen render function because this will reach the client!'
);
try {
// In development, if you're running into a hard to track down error with
// the render hydrogen stack and fighting against the multiple layers of
// complexity with `child_process `and `vm`; you can get away with removing
// the `child_process` part of it by using
// `render-hydrogen-to-string-unsafe` directly.
// ```js
// const _renderHydrogenToStringUnsafe = require('../hydrogen-render/render-hydrogen-to-string-unsafe');
// const hydrogenHtmlOutput = await _renderHydrogenToStringUnsafe(renderOptions);
// ```
//
// We use a child_process because we want to be able to exit the process after
// we receive the SSR results. We don't want Hydrogen to keep running after we
// get our initial rendered HTML.
const hydrogenHtmlOutput = await runInChildProcess(
resolvedRenderHydrogenToStringUnsafeScriptPath,
renderOptions,
{
timeout: RENDER_TIMEOUT,
abortSignal,
}
);
return hydrogenHtmlOutput;
} catch (err) {
// No need to wrap these errors since the abort originates from outside of the
// render process. And makes it easier to detect without having to look for
// underlying causes.
if (err instanceof RouteTimeoutAbortError || err instanceof UserClosedConnectionAbortError) {
throw err;
} else {
throw new RethrownError(
`Failed to render Hydrogen to string. In order to reproduce, feed in these arguments into \`renderHydrogenToString(...)\`:\n renderHydrogenToString arguments: ${JSON.stringify(
renderOptions
)}`,
err
);
}
}
}
module.exports = renderHydrogenToString;