Remove --arch in favor of DOCKER_DEFAULT_PLATFORM env var

CHANGELOG.rst

@@ -1,6 +1,14 @@
 Changelog
 =========
 
+
+2023-05-24
+----------
+
+* Removed `--arch` param from `./build.py` in favor of Docker's
+  `DOCKER_DEFAULT_PLATFORM` environment variable.
+
+
 2023-05-11
 ----------
 

README.rst

@@ -11,9 +11,10 @@ To locally build an image, run the following command::
 
    ./build.py --repo divio/base --tag 0.00-py3.6-alpine3.7 build
 
-To build for a specific architecture (eg. ARM64), add `--arch` flag::
+To build for a different architecture then your machine's one, set the
+`DOCKER_DEFAULT_PLATFORM` environment variable::
 
-   ./build.py --repo divio/base --arch arm64 --tag 1.1-py3.11-slim-bullseye build
+   DOCKER_DEFAULT_PLATFORM=linux/arm64 ./build.py --repo divio/base --tag 1.1-py3.11-slim-bullseye build
 
 Check `./build.py --help` for additional information.
 

build.py

@@ -29,16 +29,14 @@ def get_context_path_from_tag(tag):
     return directory
 
 
-def get_build_command(repo, tag, target, arch):
+def get_build_command(repo, tag, target):
     return [
         "docker",
         "build",
         "-t",
         get_image_name(repo, tag, target),
         "--build-arg",
         "TARGET={}".format(target),
-        "--build-arg",
-        "TARGETARCH={}".format(arch),
         "--no-cache",
         get_context_path_from_tag(tag=tag),
     ]
@@ -124,11 +122,6 @@ def main():
         default=os.environ.get("TARGET", "prod"),
         help="The build target (dev or prod).",
     )
-    parser.add_argument(
-        "--arch",
-        default=os.environ.get("ARCH", "amd64"),
-        help="The build architecture (amd64, arm64, x86_64 etc).",
-    )
 
     args = parser.parse_args()
 
@@ -144,7 +137,6 @@ def main():
         repo = str(args.repo)
         tag = str(args.tag)
         target = str(args.target)
-        arch = str(args.arch)
     if not (repo and tag and target):
         print("Missing parameters!")
         exit(code=1)
@@ -157,15 +149,14 @@ def main():
 
     if operation == "build":
         command = get_build_command(
-            repo=repo, tag=tag, target=target, arch=arch
+            repo=repo, tag=tag, target=target
         )
     elif operation == "test":
         command = get_test_command(repo=repo, tag=tag, target=target)
 
     print("repo: {}".format(repo))
     print("tag: {}".format(tag))
     print("target: {}".format(target))
-    print("arch: {}".format(arch))
     print("command:")
     print(" ".join(command))
     os.execvp(command[0], command)

py3.10-slim-bullseye/Dockerfile

@@ -2,7 +2,7 @@
 FROM python:3.10.11-slim-bullseye AS build
 
 ARG TARGET=prod
-ARG TARGETARCH=amd64
+ARG TARGETARCH
 
 ENV PYTHONUNBUFFERED=1 \
     PATH=/root/.local/bin:$PATH \

py3.11-slim-bullseye/Dockerfile

@@ -2,7 +2,7 @@
 FROM python:3.11.3-slim-bullseye AS build
 
 ARG TARGET=prod
-ARG TARGETARCH=amd64
+ARG TARGETARCH
 
 ENV PYTHONUNBUFFERED=1 \
     PATH=/root/.local/bin:$PATH \

py3.8-slim-buster/Dockerfile

@@ -2,7 +2,7 @@
 FROM python:3.8.16-slim-buster AS build
 
 ARG TARGET=prod
-ARG TARGETARCH=amd64
+ARG TARGETARCH
 
 ENV PYTHONUNBUFFERED=1 \
     PATH=/root/.local/bin:$PATH \

py3.9-slim-buster/Dockerfile

@@ -2,7 +2,7 @@
 FROM python:3.9.16-slim-buster AS build
 
 ARG TARGET=prod
-ARG TARGETARCH=amd64
+ARG TARGETARCH
 
 ENV PYTHONUNBUFFERED=1 \
     PATH=/root/.local/bin:$PATH \