hack: rework container_build function

Depending on the container engine and the target architecture,
multiple commands need to be executed to prepare the environment,
build the image, and clean up artifacts afterward.

To streamline this process, a tasks array (an array of lambdas) has
been introduced, its elements are executed sequencally at the end
of the container_build function.

Signed-off-by: Alexander Bachmann <a.t.bachmann@gmail.com>

Author: abachmann

hack/build-image

@@ -125,7 +125,6 @@ QUAL_FQIN = 'fqin'
 
 
 _DISCOVERED_CONTAINER_ENGINES = []
-_BUILDX_BUILDER_NAME = "samba-in-kubernetes"
 
 
 def check_kind(kind):
@@ -205,34 +204,41 @@ def container_engine(cli):
 def container_build(cli, target):
     """Construct and execute a command to build the target container image."""
     eng = container_engine(cli)
-    args = [eng, "build"]
-
-    if "docker" in args[0]:
-        # if the target arch and the host_arch are not the same, we need to use buildx
-        if target.arch != host_arch():
-            args = [
-                eng,
-                "buildx",
-                "build",
-                f"--builder={_BUILDX_BUILDER_NAME}",
-                f"--platform=linux/{target.arch}",
-                "--load"
-            ]
-            # Docker's default builder only supports the host architecture.
-            # Therefore, we need to create a new builder to support other
-            # architectures. Errors are suppressed to prevent issues when
-            # the builder is already available - this can be improved later.
-            run(cli, [eng, "buildx", "create", f"--name={_BUILDX_BUILDER_NAME}"], check=False)
-    elif target.arch != host_arch() or FORCE_ARCH_FLAG:
-        # We've noticed a few small quirks when using podman with the --arch
-        # option. The main issue is that building the client image works
-        # but then the toolbox image fails because it somehow doesn't see
-        # the image we just built as usable. This doesn't happen when
-        # --arch is not provided. So if the target arch and the host_arch
-        # are the same, skip passing the extra argument.
-        args.append(f"--arch={target.arch}")
-
-    run(cli, args + create_common_container_engine_args(cli, target), check=True)
+    tasks = []
+
+    # For docker cross-builds we need to use buildx
+    if "docker" in eng and target.arch != host_arch():       
+        args = [eng, "buildx"]
+
+        # Docker's default builder only supports the host architecture.
+        # Therefore, we need to create a new builder to support other
+        # architectures, and we must ensure we start with a fresh builder
+        # that does not contain any images from previous builds.
+        tasks.append(lambda : run(cli, args + ["rm", target.flat_name()], check=False))
+        tasks.append(lambda : run(cli, args + ["create", f"--name={target.flat_name()}"], check=True))
+
+        tasks.append(lambda : run(cli, args + [
+            "build",
+            f"--builder={target.flat_name()}",
+            f"--platform=linux/{target.arch}",
+            "--load"] + create_common_container_engine_args(cli, target), check=True))
+
+        tasks.append(lambda : run(cli, args + ["rm", target.flat_name()], check=True))
+    else:
+        args = [eng, "build"]
+        if target.arch != host_arch() or FORCE_ARCH_FLAG:
+            # We've noticed a few small quirks when using podman with the --arch
+            # option. The main issue is that building the client image works
+            # but then the toolbox image fails because it somehow doesn't see
+            # the image we just built as usable. This doesn't happen when
+            # --arch is not provided. So if the target arch and the host_arch
+            # are the same, skip passing the extra argument.
+            args += [f"--arch={target.arch}"]
+ 
+        tasks.append(lambda : run(cli, args + create_common_container_engine_args(cli, target), check=True))
+
+    for task in tasks:
+        task()
 
 def create_common_container_engine_args(cli, target):
     args = []