Support text/plain response as streaming request body

[mgyucht]

Changes

For APIs using the text/plain content type (today, only usage download), support these by simply streaming the response body back to the end user. This way, they can read the response and save it to a file or post-process it further.

Tests

Made a simple app that downloads billable usage to a temporary file:

package main

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"os"

	databricks "github.com/databricks/databricks-sdk-go"
	"github.com/databricks/databricks-sdk-go/logger"
	"github.com/databricks/databricks-sdk-go/service/billing"
)

func writeToTempFile(r io.ReadCloser) (*os.File, error) {
	// Ensure r is closed after reading
	defer r.Close()

	// Create a temporary file
	tmpFile, err := ioutil.TempFile("", "prefix-")
	if err != nil {
		return nil, err
	}

	// Copy data from io.ReadCloser to the temporary file
	_, err = io.Copy(tmpFile, r)
	if err != nil {
		tmpFile.Close() // Close and remove temporary file in case of errors
		os.Remove(tmpFile.Name())
		return nil, err
	}

	// Rewind the temporary file for further reading
	tmpFile.Seek(0, io.SeekStart)

	return tmpFile, nil
}

func main() {
	logger.DefaultLogger = &logger.SimpleLogger{Level: logger.LevelTrace}
	a, err := databricks.NewAccountClient(&databricks.Config{
		Profile:      "...",
		DebugHeaders: true,
	})
	if err != nil {
		panic(err)
	}
	ctx := context.Background()
	res, err := a.BillableUsage.Download(ctx, billing.DownloadRequest{
		StartMonth:   "2023-08",
		EndMonth:     "2023-09",
		PersonalData: true,
	})
	if err != nil {
		panic(err)
	}
	tmp, err := writeToTempFile(res.Contents)
	if err != nil {
		panic(err)
	}
	fmt.Printf("tmp: %v\n", tmp.Name())
}

This works.

Note that this test depends on a change to the content type for the OpenAPI spec for usage download to match the true content type.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Files	Coverage Δ
openapi/model.go	5.19% <ø> (ø)

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