A Contrarian Viewpoint on Container Networking by James Kelly

With DockerCon in Austin happening this week, I’m reminded of last year’s DockerCon Seattle, and watching some announcements with utter fascination or utter disappointment. Let’s see if we can’t turn the disappointments into positives.

The first disappointment has a recent happy ending. It was a broadly shared observation in Seattle, the media, and discussion forums: Docker was overstepping when they bundled in Swarm with the core of Docker Engine in 1.12. This led to the trial balloon that forking Docker was a potential solution towards a lighter-weight Docker that could serve in Mesos and Kubernetes too. Last September I covered this in my blog sparing little disdain over the idea of forking Docker Engine simply because it had become too monolithic. There are other good options, and I’m happy to say Docker heeded the community’s outcry and cleanly broke out a component of Docker Engine called containerd which is the crux of the container runtime. This gets back to the elegant Unix-tool inspired modularization and composition, and I’m glad to see containerd and rkt have recently been accepted into the CNCF. Crisis #1 averted.

My next disappointment was not so widely shared, and in fact it is still a problem at large today: the viewpoint on container networking. Let’s have a look.

Is container networking special?

When it comes to containers, there’s a massive outpour of innovation from both mature vendors and startups alike. When it comes to SDN there’s no exception.

Many of these solutions you can discount because, as I said in my last blog, as shiny and interesting as they may be on the surface or in the community, their simplicity is quickly discovered as a double-edged sword. In other words, they may be easy to get going and wrap your head around, but they have serious performance issues, security issues, scale issues, and “experiential cliffs” to borrow a turn of phrase from the Kubernetes founders when they commented on the sometimes over-simplicity of many PaaS systems (iow. they hit a use case where the system just can’t do that experience/feature that is needed).

Back to DockerCon Seattle…

Let’s put aside the SDN startups that to various extents suffer from the over-simplicity or lack of soak and development time, leading to the issues above. The thing that really grinds my gears about last year’s DockerCon can be boiled down to Docker, a powerful voice in the community, really advocating that container networking was making serious strides, when at the same time they were using the most primitive of statements (and solution) possible, introducing “Multi-host networking”

You may recall my social post/poke at the photo of this slide with my sarcastic caption.

Of course, Docker was talking about their overlay-based approach to networking that was launched as the (then) new default mode to enable networking in Swarm clusters. The problem is that most of the community are not SDN experts, and so they really don’t know any better than to believe this is an aww!-worthy contribution. A few of us that have long-worked in networking were less impressed.

Because of the attention that container projects get, Docker being the biggest, these kind of SDN solutions are still seen today by the wider community of users as good networking solutions to go with because they easily work in the very basic CaaS use cases that most users start playing with. Just because they work for your cluster today, however, doesn’t make them a solid choice. In the future your netops team will ask about X, Y and Z (and yet more stuff down the road they won’t have the foresight to see today). Also in the future you’ll expand and mature your use cases and start to care about non-functional traits of the network which often happens too late in production or when problems arise. I totally get it. Networking isn’t the first thing you want to think about in the cool new world of container stacks. It’s down in the weeds. It’s more exciting to contemplate the orchestration layer, and things we understand like our applications.

On top of the fact that many of these new SDN players offer primitive solutions with hidden pitfalls down the road that you won’t see until it’s too late, another less pardonable nuisance is the fact that most of them are perpetrating the myth that container networking is somehow special. I’ve heard this a lot in various verbiage over the ~7 years that SDN has arisen for cloud use cases. Just this week, I read a meetup description that started, “Containers require a new approach to networking.” Because of all the commotion in the container community with plenty of new SDN projects and companies having popped up, you may be duped into believing that, but it’s completely false. These players have a vested interest, though, in making you see it that way.

The truth about networking containers

The truth is that while workload connectivity to the network may change with containers (see CNM or CNI) or with the next new thing, the network itself doesn’t need to change to address the new endpoint type. Where networks did need some work, however, is on the side of plugging into the orchestration systems. This meant that networks needed better programmability and then integration to connect-up workloads in lock-step with how the orchestration system created, deleted and moved workloads. This meant plugging into systems like vSphere, OpenStack, Kubernetes, etc. In dealing with that challenge, there were again two mindsets to making the network more programmable, automated, and agile: one camp created totally net-new solutions with entirely new protocols (OpenFlow, STT, VxLAN, VPP, etc.), and the other camp used existing protocols to build new more dynamic solutions that met the new needs.

Today the first camp solutions are falling by the wayside, and the camp that built based on existing open standards and with interoperability in mind is clearly winning. OpenContrail is the most successful of these solutions.

The truth about networks is that they are pervasive and they connect everything. Interoperability is key. 1) Interoperability across networks: If you build a network that is an island of connectivity, it can’t be successful. If you build a network that requires special/new gateways, then it doesn’t connect quickly and easily to other networks using existing standards, and it won’t be successful. 2) Interoperability across endpoints connections: If you build a network that is brilliant at connecting only containers, even if it’s interoperable with other networks, then you’ve still created an island. It’s an island of operational context because the ops team needs a different solution for connecting bare-metal nodes and virtual machines. 3) Interoperability across infrastructure: If you have an SDN solution that requires a lot from the underlay/underlying infrastructure, it’s a failure. We’ve seen this with SDNs like NSX that required multicast in the underlay. We’ve seen this with ACI that requires Cisco switches to work. We’ve even seen great SDN solutions in the public cloud, but they’re specific to AWS or GCP. If your SDN solution isn’t portable anywhere, certainly to most places, then it’s still doomed.

If you want one unified network, you need one SDN solution

This aspect of interoperability and portability actually applies to many IT tools if you’re really going to realize a hybrid cloud and streamline ops, but perhaps nowhere is it more important than in the network because of its inherently pervasive nature.

If you’re at DockerCon this week, you’ll be happy to know that the best solution for container networking, OpenContrail, is also the best SDN for Kubernetes, Mesos, OpenStack, NFV, bare-metal node network automation, and VMware. While this is one SDN to rule and connect them all, and very feature rich in its 4th year of development, it’s also never been more approachable, both commercially turn-key and in open source. You can deploy it on top of any public cloud or atop of private clouds with OpenStack or VMware, or equally easily on bare-metal CaaS, especially with Kubernetes, thanks to Helm.

Please drop by and ask for an OpenContrail demo and sticker! for your laptop or phone at the Juniper Networks booth, and booths of partners of Juniper’s that have Juniper Contrail Networking integrations: Red Hat, Mirantis, Canonical, and we’re now happy to welcome Platform9 to the party too. We at Juniper will be showcasing a joint demo with Platform9 that you can read more about on the Platform9 blog.

PS. If you’re running your CaaS atop of OpenStack, then even more reason that you’ll want to stop by and get a sneak peak of what you’ll also hear more about at the upcoming Red Hat and OpenStack Summits in Boston.

Meet the Fockers! What the Fork? by James Kelly

In the past week, all the rage (actual hacker rage in some forums) in the already hot area of containers is about forking Docker code, and I have to say, “what the fork?”

What the Fork?

Really!? Maybe it is because I work in IT infrastructure, but I believe standards and consolidation are good and useful...especially “down in the weeds,” so that we can focus on the bigger picture of new tech problems and the apps that directly add value. This blog installment summarizes Docker’s problems of the past year or so, introduces you to the “Fockers” as I call them, and points out an obvious solution that, strangely, very few folks are mentioning.

This reminds me of the debate about overlay networking protocols a few years back – only then we didn’t blow up Twitter doing it. This is a bigger deal than that of overlay protocols however, so my friends in networking may relate this to deciding upon the packet standard (a laugh about the joy of standards). We have IP today, but it wasn’t always so pervasive.

Docker is actually decently pervasive today as far as containers go, so if you’re new to this topic, you might wonder where the problem is. Quick recap… The first thing you should know is that Docker is not one thing, even though we techies talk about it colloquially like this. There’s Docker Inc., Docker’s open source github code and the community and Docker products. Most notably, Docker Engine is usually just “Docker,” and even that is actually a cli tool and a daemon (background process). The core tech that made Docker famous is a packaging, distribution, and execution wrapper over Linux containers that is very developer and ops friendly. It was genius, open source, and everyone fell in love. There were cheers of “lightning in a bottle,” and “VMs are the new legacy!” Even Microsoft has had a whale of a time joining the Docker ecosystem more and more.

Containers and good tech around them has absolutely let tech move faster, transforming CI/CD, devops, cloud computing, and NFV, well…it hasn’t quite hit NFV absolutely yet, but that’s a different blog.

Docker wasn’t perfect, but when they delivered v1.0 (summer 2014), it was very successful. But then something happened. Our darling started to make promises she didn’t keep and worse, she got fat. No not literally, but Docker received a lot more VC funding, and grew organically and with a few acquisitions. This product growth took them away from just running and wrapping containers into orchestration, analytics, networking etc. (Hmm. Reminds me of VMware actually. Was that successful for them? :/) Growing adjacent or outside of core competencies is always difficult for businesses, let alone doing it with the pressure of having taken VC funding and expected to multiply it. At the same time, as Docker started releasing more features and more frequently, quality and performance suffered.

By and large I expect that most folks using Docker, weren’t using it with Docker Inc. nor anyone’s support, but nonetheless, with Docker dissatisfaction, boycotts and breakups starting to surface, in came some alternatives: fairly new entrants Core OS and Rancher, with more support from other traditional Linux vendors Red Hat (Project Atomic) and Canonical (LXD).

Containers, being fundamentally enabled by the Linux kernel, all Linux vendors have some stake in seeing that containers remain successful and proliferate. Enter OCP – wait that name is taken – OCI, I mean OCI. OCI aims to standardize a container specification: What goes in the container “packet” both as an on-disk and portable file format and what it means to a runtime. If we can all agree on that, then we can innovate around it. There is also a reference implementation, runC, donated by Docker, and I believe that as of Docker Engine v1.11 it adheres to the specification. However, according to the OCI site, the spec is still in progress, which I interpret as a moving target.

You may imagine the differing opinions at the OCI table (and thrown across blogs and Twitter – more below if you’re in the mood for some tech drama) and otherwise just the slow progress has some folks wanting to fork Docker so we can quickly get to a standard.

But wait there’s more! In Docker v1.12, near-released and announced at DockerCon June 2016, Docker Inc. refactored their largest tool, called Swarm, into the Docker Engine core product. When Docker made acquisitions like SocketPlane that competed with the container ecosystem, it stepped on the toes of other vendors, but they have a marketing mantra to prove they’re not at all malevolent: “Batteries included, but replaceable.” Ok fine we’ll overlook some indiscretions. But what about bundling the Swarm orchestration tools with Docker Engine? Those aren’t batteries. That’s bundling an airline with the sale of the airplanes.

Swarm is competing with Kubernetes, Mesosphere and Nomad for container orchestration (BTW. Kubernetes and Kubernetes-based PaaSs are the most popular currently), and this Docker move appears to be a ploy to force feed Docker users with Swarm whether they want it or not. Of course they don’t have to use it, but it is grossly excessive to have around if not used, not to mention detrimental to quality, time-to-deploy, and security. For many techies, aside from being too smart to have the Swarm pulled over their eyes, this was the last straw for another technical reason: the philosophy that decomposition into simple building blocks is good, and solutions should be loosely coupled integrations of these building blocks with clean, ideally standardized, interfaces.

Meet the Fockers! So, what do you when you are using Docker, but you’re increasingly are at odds with the way that Docker Inc. uses its open source project as a development ground for a monolithic product, a product you mostly don’t want? Fork them!

Especially among hard-core open source infrastructure users, people have a distaste for proprietary appliances, and Docker Engine is starting to look like one. All-in-ones are usually not so all-in-wonderful. That’s because functions built as decomposed units can proceed on their own innovation paths with more focus and thus, more often than not, beat the same function in an all-in-one. Of course, I’m not saying all-in-ones aren’t right for some, but they’re not for those that demand the best, nor for those that want choice to change components instead of getting locked into a monolith.

All-in-ones are usually not so all-in-wonderful.

Taking all this into account, all the talk of forking Docker seems bothersome to me for a few reasons.

First of all there are already over 10000 forks of Docker. Hello! Forking on github is click-button easy, and many have done it. As many have said, forking = fragmentation, and makes it harder for those that need to use and support multiple forks or test integrations with them aka the container ecosystem of users and vendors.

Second, creating a fork, someone presumably wants to change their fork (BTW non-techies, that’s the new copy that you now own – thanks for reading). I haven’t seen anybody actually comment on what they would change if they forked the Docker code. All this discussion and no prescription :( Presumably you would fix bugs that affect you or try to migrate fixes that others have developed, including Docker Inc who will obviously continue to develop them. What else would you do? Probably scrap Swarm because most of you (in discussions) seem to be Kubernetes fans (me too). Still, in truth you have to remove and split out a lot more if you really want to decompose this into its basic functions. That’s not trivial.

Third, let’s say there is “the” fork. Not my fork or yours, but the royal fork. Who starts this? Who do you think should own it? Maybe it would be best for Docker if they just did this! They could re-split out Swarm and other tools too.

Don’t fork, make love.

Finally, and my preferred solution. Don’t fork, make love. In seriousness, what I mean is two things:

1.       There is a standards body, the OCI. Make sure Docker has a seat at the table, and get on with it! If they’re not willing to play ball, then let it be widely known, and move OCI forward without them. I would think they have the most to lose here, so they would cooperate. The backlash if they didn’t may be unforgiving.

2.       There is already a great compliant alternative to Docker today that few are talking about: rkt (pronounced Rocket). This is pioneered by CoreOS, and now supported on many Linux operating systems. rkt is very lightweight. It has no accompanying daemon. It is a single, small, simple function that helps start containers. Therefore, it passes the test of a small decomposed function. Even better, the most likely Fockers are probably not Swarm users, and all other orchestration systems support rkt: Kubernetes’s rktnetes, Mesos’s unified containerizer, and Nomad’s rkt driver. We all have a vote, with our wallet and free choices, so maybe it is time rock it on over to rkt.


In closing, I offer some more ecosystem observations:

In spite of this criticism (much is not mine in fact, but that of others to which I’m witness) I’m a big fan of Docker and its people. I’m not a fan of recent strategy to include Swarm into core however. I believe it goes against the generally accepted principles of computer science and Unix. IMO Docker Engine was already too big pre-v1.12. Take it out, and compete on the battle ground of orchestration on your own merits and find new business models (like Docker Cloud).

I feel like the orchestration piece is important and the momentum is with Kubernetes. I see the orchestration race a little like OpenStack vs. Cloud Stack vs. Eucalyptus 5 years ago where the momentum then was with OpenStack, and today it’s with Kubernetes but for different reasons. It has well-designed and cleanly defined interfaces and abstractions. It is very easy to try and learn. Those who say it is hard to learn, setup and use, what was your experience with OpenStack? Moreover, there are tons of vanilla Kubernetes users; can’t say that about OpenStack. In the OpenStack space, there are OpenStack vendors adding value with support and getting to day-1, but with Kubernetes the vendor space is adding features on top of Kubernetes, moving toward PaaS. That’s a good sign that the Kubernetes scope is about right.

I’ve seen 99% Docker love and 1% anti-Docker sentiment in my own experience. My employer, Juniper, is a Docker partner and uses Docker Engine. We have SDN and switching integrations for Docker Engine, and so personally, my hope is that Docker finds a way through this difficulty by re-evaluating how it is using open source and business together. Open source is not a vehicle to drive business nor shareholder value which is inherently competitive. Open source is a way to drive value to the IT community at large in a way that is intentionally cooperative.