- [Instructor] According to the Docker
Certified Associate Exam Blueprint
when it comes to orchestration, you should be able
to sketch how a Dockerized application communicates
with legacy systems.
Now, of course, on the exam, they aren't going
to ask you to actually draw a sketch.
The point here is that you need
to understand some basic Docker networking concepts.
However, there's a lot to know
about Docker container networking,
but here's a quick overview of some of the fundamentals.
Now, similar in concept to virtual machines,
Docker containers have a few different options
when it comes to networking.
For example, by default, container networks are bridged
to the host network that they're running on.
In this diagram, you can see that we have a web
and database container and they share the same IP address
as the host that they're running on.
For the applications running in those containers
to connect out to the physical network,
talk to physical hosts, legacy applications,
maybe even out to the internet, they would go
through the traditional physical network,
exiting the Docker host
through the Docker's default ethernet interface.
So, as you see here, the two web containers running
on the Docker host are able to communicate
through the physical network adapter
on the Docker host to the physical servers running
out in, for example, a data center.
Now, other Docker container networking options allow you
to isolate the containers on their own network, for example,
connecting just one container to a network
to isolate that container or you could isolate a handful
of containers creating a private container network
just for those containers.
Docker also offers the overlay networking feature
that allows containers on multiple hosts
to communicate on a private network tunneling
through the physical network to do so.
For more information on Docker container networking,
I recommend that you take some time
to review the Docker reference architecture
that covers designing scalable
and portable Docker container networks.
It offers a number of other diagrams
besides the one that I showed here
on the Docker container networking model
and goes into great detail
on how Docker container networking works.
For complete coverage of Docker container networking,
check out my other course in this Docker learning path
on Docker container networking.