feat: As a user, I want to to use the body-transformer plugin for other data formats without warnings

[jesse-r-s-hines]

Description

The body-transformer plugin is a very flexible plugin to modify the body content of requests and responses, and we can already use the body-transformer plugin to manipulate arbitrary data formats with the lua templates. However, if you don't specify input_format and Content-Type isn't JSON or XML it will always log a warning about "no input format to parse request/response body".

Adding another format to the input_format enum, none, that explicitly tells body-transformer to not try to parse or validate the body content and silences this warning would be convenient.

[shreemaan-abhishek]

would you like to contribute this?

[jesse-r-s-hines]

Sorry for the late reply. I probably won't get time to work on this one myself.

[smileby]

@shreemaan-abhishek feel good, I'd like to try it if needed ☺

[smileby]

@jesse-r-s-hines @shreemaan-abhishek
Hi, Can you provide a more detailed idea?
I have two questions:

• If no try to parse or validate are performed when set to none, does it need to process the template content?
• input_format is not specified and the Content-Type is not JSON or XML, is there an example of the request that can be provided and what to expect after execution?

Or have a better idea

[jesse-r-s-hines]

Currently, if you do not specify input_format and there's no Content-Type header the plugin will skip trying to parse the response body. This allows arbitrary transformations as it doesn't try to parse the body but still runs the template which can access the original body with _body.

The only problem is it spams warnings about "no input format to parse response body". I'd like an explicit "input_format": "none" to just silence that warning.

In our case we also have an upstream service that sometimes returns incorrect Content-Type headers, so it would be nice if "input_format": "none" caused it to not try to parse the content regardless of Content-Type and let the template logic do whatever is necessary to convert to the correct format. Currently if you don't strip Content-Type with response-rewrite the plugin will abort before calling the template if it can't parse the original response.

So something like:

Original response:

Content-Type: application/json
Body:
not actually json

Config:

"body-transformer": {
    "response": {
        "template": "{\"message\": \"{* string.gsub(_body, 'not ', '') *}\"}"
    }
}

Transformed response:

Content-Type: application/json
Body:
{"message": "actually json"}

Thanks!

[smileby]

@jesse-r-s-hines @shreemaan-abhishek
Hi, I submitted a PR to solve this issue. Please help confirm the correctness.