remove image remote http format sniffing based on HTTP Range

Instead:

- Use the file extension
- Only auto-detect if no format is specified, unlike the current
  implmentation which always autodetects and errors on inconsistency
  of specified vs auto-detected.

Closes: #958

Author: dmacvicar

libvirt/resource_libvirt_volume.go

@@ -127,6 +127,7 @@ func resourceLibvirtVolumeCreate(ctx context.Context, d *schema.ResourceData, me
 		if _, ok := d.GetOk("size"); ok {
 			return diag.Errorf("'size' can't be specified when also 'source' is given (the size will be set to the size of the source image")
 		}
+
 		if _, ok := d.GetOk("base_volume_id"); ok {
 			return diag.Errorf("'base_volume_id' can't be specified when also 'source' is given")
 		}
@@ -139,17 +140,16 @@ func resourceLibvirtVolumeCreate(ctx context.Context, d *schema.ResourceData, me
 			return diag.FromErr(err)
 		}
 
-		// figure out the format of the image
-		isQCOW2, err := img.IsQCOW2()
-		if err != nil {
-			return diag.Errorf("error while determining image type for %s: %s", img.String(), err)
-		}
-		if isQCOW2 {
-			volumeDef.Target.Format.Type = "qcow2"
-		}
+		// if no format is given, autodetect
+		if !isFormatGiven {
+			isQCOW2, err := img.IsQCOW2()
+			if err != nil {
+				return diag.Errorf("error while determining image type for %s: %s", img.String(), err)
+			}
 
-		if isFormatGiven && isQCOW2 && givenFormat != "qcow2" {
-			return diag.Errorf("format other than QCOW2 explicitly specified for image detected as QCOW2 image: %s", img.String())
+			if isQCOW2 {
+				volumeDef.Target.Format.Type = "qcow2"
+			}
 		}
 
 		// update the image in the description, even if the file has not changed

libvirt/volume_image.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"path"
 	"path/filepath"
 	"runtime"
 	"strconv"
@@ -126,37 +127,8 @@ func (i *httpImage) Size() (uint64, error) {
 	return uint64(length), nil
 }
 
-//nolint:mnd
 func (i *httpImage) IsQCOW2() (bool, error) {
-	client := &http.Client{}
-	req, _ := http.NewRequest("GET", i.url.String(), nil)
-	req.Header.Set("Range", "bytes=0-7")
-	response, err := client.Do(req)
-	if err != nil {
-		return false, err
-	}
-	defer response.Body.Close()
-
-	if response.StatusCode != http.StatusPartialContent {
-		return false, fmt.Errorf(
-			"can't retrieve partial header of resource to determine file type: %s - %s",
-			i.url.String(),
-			response.Status)
-	}
-
-	header, err := io.ReadAll(response.Body)
-	if err != nil {
-		return false, err
-	}
-
-	if len(header) < 8 {
-		return false, fmt.Errorf(
-			"can't retrieve read header of resource to determine file type: %s - %d bytes read",
-			i.url.String(),
-			len(header))
-	}
-
-	return isQCOW2Header(header)
+	return strings.ToLower(strings.TrimPrefix(path.Ext(i.url.Path), ".")) == "qcow2", nil
 }
 
 func (i *httpImage) Import(uploader func(io.Reader) error, vol libvirtxml.StorageVolume) error {