Preserve response body on api requests with XML response types.

[taeold]

Today, apiv2 will try to parse XML responses as JSON with poor results, e.g.

⚠ functions: Upload Error: Unable to parse JSON: SyntaxError: Unexpected token < in JSON at position 0

Error: Unable to parse JSON: SyntaxError: Unexpected token < in JSON at position 0

Here, we explicitly add support for xml as a responseType and deal with it as a string. E.g.

⚠  functions: Upload Error: HTTP Error: 400, <?xml version='1.0' encoding='UTF-8'?><Error><Code>EntityTooLarge</Code><Message>Your proposed upload is larger than the maximum object size specified in your Policy Document.</Message><Details>Content-length exceeds upper bound on range</Details></Error>

Error: HTTP Error: 400, <?xml version='1.0' encoding='UTF-8'?><Error><Code>EntityTooLarge</Code><Message>Your proposed upload is larger than the maximum object size specified in your Policy Document.</Message><Details>Content-length exceeds upper bound on range</Details></Error>

Fixes #4146

[bkendall]

Forgive me a silly question: could we not just add accept: application/json to get JSON responses from this API? Or does it exclusively respond in XML?

It feels a little weird to add support for XML for a single place - not that it's wrong, but everywhere else returns JSON, so it's an outlier...

[taeold]

It's strictly an XML endpoint we are using since the URL returned by GCF when we call "generateUploadURL" works against it:

https://cloud.google.com/storage/docs/xml-api/overview

We could do some work to move everything to JSON API

https://cloud.google.com/storage/docs/json_api/v1/buckets/patch

But that's gonna be a lot more work than this.

[taeold]

(Looks like XML is the encoding of choice over JSON in the storage API world)

[taeold]

whoops more correct answer - signed URL only supports XML API:

https://cloud.google.com/storage/docs/access-control/signed-urls