This only works with "Text" body types like JSON/XML/etc. Other body types, like form application/x-www-form-urlencoded, have a body object that looks different:

{
  mimeType: 'application/x-www-form-urlencoded', 
  params: [{name: 'foo', value: 'bar'}]
}

The final body for these content-types is computed a few lines above, making it pretty easy to support application/x-www-form-urlencoded. However, binary uploads and multipart/form-data are handled by Curl so we don't ever know the final result of those. It would be possible to handle those other two cases ourselves but would take more work (maybe not worth it).

For the cases we don't support, it's probably worth throwing an error. The following code will throw an error for anything that isn't Text or application/x-www-form-urlencoded.

const isForm = body.mimeType === 'multipart/form-data';
const isFile = body.fileName;
const isUnsupported = isForm || isFile;
if (isUnsupported) {
  throw new Error('AWS authentication not supported for provided body type');
}

For x-www-form-urlencoded if it's all just name/contents pairs I can convert that to a final string so aws4 can add it to the signature. But if there's file uploads I'm not sure how to get that to work properly.

I've added the code for an exception for unsupported bodies. Here's my remaining questions:

• Do you want me to convert the x-www-form-urlencoded array of key/value objects which we pass to curl to a finalized and encoded string so it can be passed into aws4 to be signed?
• When running under npm run dev I can see the unsupported body exception is thrown but the UI doesn't seem to indicate this anywhere.
• I'm seeing my entered auth values disappear as I navigate off the AWS tab. Is that expected? Is there something about the new code that's not right that's causing that?

Not sure what AWS expects here, but should this be parsedUrl.host instead of parsedUrl.hostname? I think the only difference is that host would include the port if it were specified.

I think parsedUrl.hostname is correct. I tried explicitly including :443 in my URL and using host but AWS gave me a 403 for that. Since in all normal cases AWS services are accessed via HTTPS using the default port, I think omitting the port is correct.

Nice 👍 Might be worth adding a comment beside it so someone doesn't ask the same question again?

Should we not be passing req.headers into this?

I don't think so. We could, but first we'd need to convert them to a node format object instead of an array of name/value objects. aws4 only looks at a few key headers (Content-Type, Content-Length, Host) plus the AWS-specific ones.

I assume this wouldn't be needed if we passed the content-type header in the initial options above?

Yes I think you're correct here. Refactoring.

Actually without this we end up sending a duplicate Content-Type header and the signature won't verify.

Ok, I think this is good now 👍

These two lines should be:

accessKeyId: oldAuth.accesKeyId || '',
secretAccessKey: oldAuth.secretAccessKey || ''

Ok, I think this is good now 👍

This should be

name: authentication.accesKeyId || '',
value: authentication.secretAccessKey || ''

This explains why you are seeing your values disappear from the UI.