add explicit buildbase option to use temporary container for backend builds

Author: kpedro88

build.py

@@ -2591,6 +2591,12 @@ def enable_all():
         required=False,
         help='Use specified Docker image in build as <image-name>,<full-image-name>. <image-name> can be "base", "gpu-base", or "pytorch".',
     )
+    parser.add_argument(
+        "--use-buildbase",
+        default=False,
+        action="store_true",
+        help='Use local temporary "buildbase" Docker image as "base" image to build backends',
+    )
 
     parser.add_argument(
         "--enable-all",
@@ -2934,6 +2940,8 @@ def enable_all():
 
     # Initialize map of docker images.
     images = {}
+    if FLAGS.use_buildbase:
+        images["base"] = "tritonserver_buildbase"
     for img in FLAGS.image:
         parts = img.split(",")
         fail_if(