You've created your application, placed it into a container, and deployed it. However, your application seems to behave strangely. It is unable to connect to the database, your configuration file doesn't load properly, or you've got an error message that doesn't really say anything. So far, you've checked your container's logs and couldn't get enough information out of them. Wouldn't it be great to enter the container and check everything manually? And here comes the docker exec command....