Add entrypoint to allow file override.

Dockerfile

@@ -1,3 +1,8 @@
 FROM nginx:latest
 
 COPY www /usr/share/nginx/html
+COPY entrypoint.sh /entrypoint.sh
+
+RUN chmod +x /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]

entrypoint.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+# Check if the folder /extra exists, if so, copy all files from /extra to /usr/share/nginx/html
+if [ -d "/extra" ]; then
+    echo "Copying files from /extra to /usr/share/nginx/html"
+    cp -r /extra/* /usr/share/nginx/html/
+fi
+
+echo "Executing command: $@"
+exec "$@"