Plugin env

[alfredosalzillo]

Added an env plugin to replace {{ENV_VAR_NAME}} with the value at compile time.

Why

It's useful to use env variables in SSG mode or SSR without using the useDeno hook.

Example usage

// file aleph.config.js
import env from 'https://deno.land/x/aleph/plugins/env.ts'
export default {
  plugins: [
   env(),
  ],
};

into code

const API_URL = '{{APP_BASE_API_URL}}';

will replace {{APP_BASE_API_URL}} with the result of Deno.env.get('APP_BASE_API_URL').

[shadowtime2000]

Not a big fan of the idea of replacing {{env variable}}. Might better to use some AST transformations instead.

[alfredosalzillo]

The problem with an AST transformation is that as of today there isn't any AST library for deno. We should use the node typescript.compileSource.

Adding the AST API to the deno namespace was discussed but for now, is on standby denoland/deno#6893 (comment).

[shadowtime2000]

@alfredosalzillo The Deno team has decided not to have an AST API in the Deno namespace but there are other solutions, like deno_swc which seems like a good one.

[shadowtime2000]

I am going to close this PR, I am going to open another issue to discuss this before we implement it.