azureblob: Add support for custom upload headers

backend/azureblob/azureblob.go

@@ -1685,6 +1685,26 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 		}
 	}
 
+	// Apply upload options (also allows one to overwrite content-type)
+	for _, option := range options {
+		key, value := option.Header()
+		lowerKey := strings.ToLower(key)
+		switch lowerKey {
+		case "":
+			// ignore
+		case "cache-control":
+			httpHeaders.CacheControl = value
+		case "content-disposition":
+			httpHeaders.ContentDisposition = value
+		case "content-encoding":
+			httpHeaders.ContentEncoding = value
+		case "content-language":
+			httpHeaders.ContentLanguage = value
+		case "content-type":
+			httpHeaders.ContentType = value
+		}
+	}
+
 	uploadParts := maxUploadParts
 	if uploadParts < 1 {
 		uploadParts = 1

docs/content/azureblob.md

@@ -514,6 +514,18 @@ Properties:
 
 {{< rem autogenerated options stop >}}
 
+### Custom upload headers
+
+You can set custom upload headers with the `--header-upload` flag. 
+
+- Cache-Control
+- Content-Disposition
+- Content-Encoding
+- Content-Language
+- Content-Type
+
+Eg `--header-upload "Content-Type: text/potato"`
+
 ## Limitations
 
 MD5 sums are only uploaded with chunked files if the source has an MD5