Add new `--bindings` command line argument

This argument is a JSON stringified array of all the bindings that are being passed from Wrangler in the same format as would be uploaded to a Worker during publishing…

For example, if you have the following vars in wrangler.toml:

[[vars]]
a = "10"
b = 20
c = { value: 30 }

Then we actually create bindings that look like:

[
 { "type": "plain_text", "name": "a", "text": "10" },
 { "type": "json", "name": "b", "json": "20" },
 { "type": "json", "name": "c", "json": "{ \"value\": 30 }" }
]

The same would apply to other binding types such as

• kv_namespace
• wasm_module
• text_blob
• durable_object_namespace
• r2_bucket

It is then up to Miniflare to parse the JSON and work out how to assign the bindings to the appropriate plugins. This would mean that Wrangler would not need to use the specific keys such as --kv, --binding, etc in a backwardly compatible way.

[mrbbot]

Hey everyone! 👋 Just had a chat with @JacobMGEvans and proposed an alternative. Instead of adding a --bindings CLI argument to Miniflare, I think Wrangler should be calling Miniflare via its API.

Basically instead of using require.resolve("miniflare/cli") here… https://github.com/cloudflare/wrangler2/blob/43417469ef071e4f673507ff1dfa11f3bde29428/packages/wrangler/src/dev.tsx#L298 …Wrangler would call its own separate script file that looked something like Miniflare’s cli.ts: https://github.com/cloudflare/miniflare/blob/870b401ef520c1826339ff060fd8a0a576392a91/packages/miniflare/src/cli.ts#L93-L104 It would be up to you to define the options format then, and you could use a stringified JSON array if you wanted. The API is much more amenable to Wrangler’s use case anyways and it already supports arbitrary bindings:

// See https://miniflare.dev/get-started/api#reference for reference
const options = {};

const bindings = JSON.parse(process.argv[2]);
for (const binding of bindings) {
  if (binding.type === "plain_text") {
    options.bindings ??= {};
    options.bindings[binding.name] = binding.text;
  }
  // ...
}

// Also already supports JSON bindings
options.bindings["b"] = 42;

const mf = new Miniflare(options);

cc @threepointone

[threepointone]

think a direct programmatic approach is cleanest, right? Rather than having another layer of indirection.

Just trying to avoid a major refactor at this point, but if that’s the only option we have, sure I guess.