Throw error if using --build-memory-limit

repo2docker/__main__.py

@@ -140,7 +140,8 @@ def get_argparser():
 
     argparser.add_argument(
         "--build-memory-limit",
-        help="Total Memory that can be used by the docker build process",
+        # Removed argument, but we still want to support printing an error message if this is passed
+        help=argparse.SUPPRESS
     )
 
     argparser.add_argument(
@@ -434,12 +435,10 @@ def make_r2d(argv=None):
         sys.exit(1)
 
     if args.build_memory_limit:
-        # if the string only contains numerals we assume it should be an int
-        # and specifies a size in bytes
-        if args.build_memory_limit.isnumeric():
-            r2d.build_memory_limit = int(args.build_memory_limit)
-        else:
-            r2d.build_memory_limit = args.build_memory_limit
+        # We no longer support build_memory_limit, it must be set in the builder instance
+        print("--build-memory-limit is no longer supported", file=sys.stderr)
+        print("Use `docker buildx create` to create a custom builder with appropriate memory limits instead", file=sys.stderr)
+        sys.exit(-1)
 
     if args.environment and not r2d.run:
         print("To specify environment variables, you also need to run " "the container")

repo2docker/app.py

@@ -165,13 +165,20 @@ class Repo2Docker(Application):
     build_memory_limit = ByteSpecification(
         0,
         help="""
-        Total memory that can be used by the docker image building process.
+        Unsupported.
 
-        Set to 0 for no limits.
+        When using docker, please use `docker buildx create` to create a new buildkit
+        builder with appropriate limits instead.
         """,
         config=True,
     )
 
+    @observe("build_memory_limit")
+    def build_memory_limit_changed(self, change):
+        print("Setting build_memory_limit is not supported", file=sys.stderr)
+        print("Use `docker buildx create` to create a custom builder with appropriate memory limits instead", file=sys.stderr)
+        sys.exit(-1)
+
     volumes = Dict(
         {},
         help="""
@@ -856,6 +863,7 @@ class Repo2Docker(Application):
                     for l in picked_buildpack.build(
                         docker_client,
                         self.output_image_spec,
+                        # This is deprecated, but passing it anyway to not break backwards compatibility
                         self.build_memory_limit,
                         build_args,
                         self.cache_from,

tests/unit/test_args.py

@@ -50,11 +50,8 @@ def test_mem_limit():
     """
     Test various ways of passing --build-memory-limit
     """
-    r2d = make_r2d(["--build-memory-limit", "1024", "."])
-    assert int(r2d.build_memory_limit) == 1024
-
-    r2d = make_r2d(["--build-memory-limit", "3K", "."])
-    assert int(r2d.build_memory_limit) == 1024 * 3
+    with pytest.raises(SystemExit):
+        r2d = make_r2d(["--build-memory-limit", "1024", "."])
 
 
 def test_run_required():