Limitations of single-host deployment
What could go wrong with deploying a Docker application to a single host? Plenty! While single-host deployment offers operational simplicity, it has some major limitations. Let's look at some of the limitations in the following sections.
No automatic failover
If either the database server container or the web service container fails and cannot be restarted automatically, the site will be down and will require manual intervention. This might be as simple as noticing that your monitoring system says that the site is down, and so you need to SSH in and reboot the server. But sometimes, a single server will be so low on memory that it must be manually rebooted from a higher-level console or even power-cycled manually. This tends to lead to significant periods of time where an application is down and not available to serve requests.
Inability to scale horizontally to accept more load
What happens if the traffic for the system exceeds...
