Persistent storage

Since we have covered transient local storage, we can now consider what other options we have for keeping data safe when the container dies or is moved. As we talked about previously, without being able to save data from the container in some fashion to an outside source if a node or the container unexpectedly dies while it is serving up something (such as your database), you will most likely lose some or all your data contained on it, which is definitively something we would like to avoid. Using some form of container-external storage for your data, like we did in earlier chapters with mounted volumes, we can begin to make the cluster really resilient and containers that run on it stateless.

By making containers stateless, you gain confidence to not worry much about exactly what container is running on which Docker Engine as long as they can pull the right image and run it with the right parameters. If you think about it for a minute, you may even notice how this approach...