When I use OWNCLOUD_SUB_URL I got the owncloud landing page, but I can`t login with the configured credentials. When I removed the OWNCLOUD_SUB_URL everthing works!
docker run --name owncloud
-e OWNCLOUD_ADMIN_USERNAME=admin
-e OWNCLOUD_ADMIN_PASSWORD=admin
-e OWNCLOUD_DB_TYPE=mysql
-e OWNCLOUD_DB_NAME=owncloud_db
-e OWNCLOUD_DB_USERNAME=xxx
-e OWNCLOUD_DB_PASSWORD=xxx
-e OWNCLOUD_DB_HOST=xxx
-e OWNCLOUD_SUB_URL=/owncloud/
-d -p 8082:8080 owncloud/server