Prgrammatic SEA blob generation API

[james-pre]

Currently, CLI commands and many files are involved in generating a SEA using Javascript.

For example:

import { execSync } from 'node:child_process';
import { copyFileSync, readFileSync, writeFileSync } from 'node:fs';
import { inject } from 'postject';

const main = 'path/to/main.js',
	blobPath = 'path/to/sea.blob',
	configPath = 'path/to/sea.json',
	outputPath = 'path/to/executable';

writeFileSync(
	configPath,
	JSON.stringify({
		main,
		output: blobPath,
		disableExperimentalSEAWarning: true,
	})
);
execSync('node --experimental-sea-config ' + configPath, { stdio: 'inherit' });
copyFileSync(process.execPath, outputPath);
await inject(outputPath, 'NODE_SEA_BLOB', readFileSync(blobPath), {
	machoSegmentName: 'NODE_SEA',
	sentinelFuse: 'NODE_SEA_FUSE_fce680ab2cc467b6e072b8b5df1996b2',
});

It would be nice if Node.js provided a Javascript API for generating SEA blobs. This would eliminate extra file creation and streamline the SEA creation process. I propose adding a function to the node:sea module/API (Typescript used for clarity):

/**
 * Configuration options for generating a SEA blob
 * @see https://nodejs.org/api/single-executable-applications.html#generating-single-executable-preparation-blobs
 */
interface BlobConfiguration {
	main: string;
	disableExperimentalSEAWarning?: boolean;
	useSnapshot?: boolean;
	useCodeCache?: boolean;
	assets?: Record<string, string>;
}

/**
 * Generates a SEA blob to be injected into an executable
 * @param config configuration options for the blob
 * @returns The blob contents in a buffer
 */
function generateBlob(config: BlobConfiguration): Buffer;

This new function in the SEA API would allow for more streamlined and readable code:

import { copyFileSync } from 'node:fs';
import { generateBlob } from 'node:sea';
import { inject } from 'postject';

const outputPath = 'path/to/executable';

const blob = generateBlob({
	main: 'path/to/main.js',
	disableExperimentalSEAWarning: true,
});
copyFileSync(process.execPath, outputPath);
await inject(outputPath, 'NODE_SEA_BLOB', blob, {
	machoSegmentName: 'NODE_SEA',
	sentinelFuse: 'NODE_SEA_FUSE_fce680ab2cc467b6e072b8b5df1996b2',
});

Which could even be inlined:

import { copyFileSync } from 'node:fs';
import { generateBlob } from 'node:sea';
import { inject } from 'postject';

const outputPath = 'path/to/executable';

copyFileSync(process.execPath, outputPath);
await inject(
	outputPath,
	'NODE_SEA_BLOB',
	generateBlob({
		main: 'path/to/main.js',
		disableExperimentalSEAWarning: true,
	}),
	{
		machoSegmentName: 'NODE_SEA',
		sentinelFuse: 'NODE_SEA_FUSE_fce680ab2cc467b6e072b8b5df1996b2',
	}
);