Category: Docker

While the pundits keeps telling me Docker is dead (looking at its documentation I would say they’re right) and Kubernetes it the way to go (yay!), some people still have to deal with Docker networking, and at least some of them found the Docker Networking Deep Dive webinar useful. Here’s a recent review:

Setting up a network automation development environment is an interesting task:

• You have to install a half-dozen tools, each one with tons of dependencies;
• SSH libraries like paramiko have to installed manually;
• Ansible modules for individual network devices might need extra libraries;
• Parsing tools invoked with Ansible Jinja2 filters have to be installed separately;
• Add your pet peeve here ;)

Now imagine having to do that for a dozen networking engineers and software developers working on all sorts of semi-managed laptops. Containers seem to be one of the sane solutions¹.

Getting Docker to work with IPv6 is an interesting and under-documented (trying to stay diplomatic) adventure, but there’s a shortcut to the promised land: even if your Docker environment is pure IPv4 morass, you can still reach published container ports over IPv6 thanks to the userland proxy I described last week. The performance is obviously commensurate with traversing kernel-user boundary too many times.

In early September I explained the difference between exposed and published Docker container ports.

Now let’s peek behind the curtain and explore how Docker uses iptables to publish container ports, and why it runs a userland proxy process for every published port.

For even more details, explore the Docker Networking Deep Dive webinar.

Last week I published an overview of how complex (networking-wise) Docker Swarm services can get. This time let’s focus on something that should have been way simpler: running container-based services on a single Linux host.

In the first part of this article I’m focusing on the basics, including exposed ports, and published ports. The behind-the-scenes details are coming in a week or so; in the meantime you can enjoy (most of them) in the Docker Networking Deep Dive webinar.

Remember the claim that networking is becoming obsolete and that everyone else will simply bypass the networking teams (source)?

Good news for you – there are many fast growing overlay solutions that are adopted by apps and security teams and bypass the networking teams altogether.

That sounds awesome in a VC pitch deck. Let’s see how well that concept works out in reality using Docker Swarm as an example (Kubernetes is probably even worse).

A Docker networking rant coming from my good friend Marko Milivojević triggered a severe case of Deja-Moo, resulting in a flood of unpleasant memories caused by too-successful “disruptive” IT vendors.

Imagine you’re working for a startup creating a cool new product in the IT infrastructure space (if you have an oversized ego you would call yourself “disruptive thought leader” on your LinkedIn profile) but nobody is taking you seriously. How about some guerrilla warfare: advertising your product to people who hate the IT operations (today we’d call that Shadow IT).

One of my readers sent me a container security question after reading the Application Container Security Guide from NIST:

We are considering segregating dev/test/prod environments with bare-metal hardware. I did not find something in the standard concerning this. What should a financial institution do in your opinion?

I am no security expert and know just enough about containers to be dangerous, but there’s a rule that usually works well: use common sense and identify similar scenarios that have already been solved.

One of my readers wanted to know more about containers and wondered how ipSpace.net materials could help him. Here’s a short step-by-step guide:

I published this blog post to help ipSpace.net subscribers navigate through Docker- and containers-related material. You might want to skip it if you’re not one of them.