fix(docker): enable IPv6 explicitly by env variable (#8449)

Enabling IPv6 address and port for IPv6 addresses
caused backward incompatible issues in the docker image.
If one wants to use it, it must be turned on explicitly
with PORT_IPV6 env variable.

Refs #8447
Refs #8437

docker/docker-entrypoint.d/40-swagger-ui.sh

@@ -39,6 +39,11 @@ if [[ -f "$SWAGGER_JSON" ]]; then
   sed -i "s|http://example.com/api|$REL_PATH|g" $INITIALIZER_SCRIPT
 fi
 
+# enable/disable the address and port for IPv6 addresses that nginx listens on
+if [[ -n "${PORT_IPV6}" ]]; then
+    sed -i "s|8080;|8080;\n    listen            [::]:${PORT_IPV6};|g" $NGINX_CONF
+fi
+
 # replace the PORT that nginx listens on if PORT is supplied
 if [[ -n "${PORT}" ]]; then
     sed -i "s|8080|${PORT}|g" $NGINX_CONF