Unlike the other two containers, we will leave the database in one container due to a combination of things:

• MongoDB can scale to high GB/low TB dataset sizes easily with vertical scaling.
• Databases are extremely difficult to scale up without in-depth knowledge of volumes (covered in the next chapter).
• Sharding and replica sets of databases are generally complicated enough for whole books to be written on this topic alone.

We may cover this topic in a later chapter, but here, it would derail us from our general goal of learning how to deploy services so we will just have our single database instance that we used in the previous chapter for now.