Try building in root directory

Dockerfile

@@ -0,0 +1,10 @@
+# SPDX-FileCopyrightText: Free Software Foundation Europe e.V.
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+# Build site
+FROM klakegg/hugo:0.101.0-ext-debian-onbuild AS hugo
+
+# Serve site
+FROM pierrezemb/gostatic
+COPY --from=hugo /target/ /srv/http/

docker-compose.yml

@@ -7,7 +7,9 @@ services:
   pmpc:
     container_name: pmpc
     build:
-      context: site
+      context: .
+      args:
+        - HUGO_DIR=/src/site
     image: pmpc
     restart: always
     logging: