Add support for --build-arg option

podman_compose.py

@@ -1071,7 +1071,7 @@ def build_one(compose, args, cnt):
     if getattr(args, 'pull_always', None): build_args.append("--pull-always")
     elif getattr(args, 'pull', None): build_args.append("--pull")
     args_list = norm_as_list(build_desc.get('args', {}))
-    for build_arg in args_list:
+    for build_arg in args_list + args.build_arg:
         build_args.extend(("--build-arg", build_arg,))
     build_args.append(ctx)
     compose.podman.run(build_args, sleep=0)
@@ -1364,6 +1364,8 @@ def compose_build_parse(parser):
         help="attempt to pull a newer version of the image", action='store_true')
     parser.add_argument("--pull-always",
         help="attempt to pull a newer version of the image, Raise an error even if the image is present locally.", action='store_true')
+    parser.add_argument("--build-arg", metavar="key=val", action="append", default=[],
+        help="Set build-time variables for services.")
 
 
 def main():

tests/build/context/Dockerfile-alt

@@ -1,7 +1,9 @@
 FROM busybox
 ARG buildno=1
 ARG httpd_port=80
+ARG other_variable=not_set
 ENV httpd_port ${httpd_port}
+ENV other_variable ${other_variable}
 RUN mkdir -p /var/www/html/ && \
     echo "ALT buildno=$buildno port=$httpd_port `date -Iseconds`" > /var/www/html/index.txt
 CMD httpd -f -p "$httpd_port" -h /var/www/html

tests/build/docker-compose.yml

@@ -17,3 +17,9 @@ services:
       image: my-busybox-httpd2
       ports:
       - 8000:8000
+    test_build_arg_argument:
+      build:
+        context: ./context
+        dockerfile: Dockerfile-alt
+      image: my-busybox-httpd2
+      command: env