Where is Docker headed?


I am heading to Copenhagen this week to attend DockerCon Europe 2017
you can still register for the conferencehere.
Because we created Rancher to serve the market needs resulting from the
widespread adoption of Docker technology, we have maintained a strong
presence at every DockerCon conference over the last three years.

DockerCon is special—not only is it a
gathering place for major industry players, it is one of the few events
that brings together far more users than vendors. The opportunity to
meet so many users in one place makes attending and sponsoring the
conference a worthwhile investment. Talking to our users and hearing
their ideas motivates us to work harder and improve the Rancher

The Docker technology evolution is
at a critical juncture, so I am particularly interested in what Docker,
Inc. will announce at this year’s DockerCon EU. We recently announced
the technical preview of Rancher
where we transitioned Rancher from a product built on Docker to a
product built on Kubernetes. As much success as Docker has achieved as
an application packaging and runtime standard, Kubernetes has overtaken
Docker in terms of container infrastructure, orchestration, and

Container infrastructure

Infrastructure goes beyond packaging and runtime; it includes storage,
networking, load balancing, and security. When we started Rancher three
years ago, we expected Docker to define industry standard plugin
interfaces for container networking and storage. Despite the excellent
work done by Docker and other early pioneers like SocketPlane (later
acquired by Docker), Weaveworks, and ClusterHQ as well as plenty of
support from industry leaders such as Cisco, EMC, and NetApp, Docker
interfaces like libnetwork, Container Network Model (CNM), and Docker
volume plugin failed to become viable standards. We tried very hard to
work with CNM and Docker volume plugins at Rancher, but we ran into
insurmountable challenges:

  1. We never figured out how to make CNM work outside of Docker’s
    built-in networking implementation. We were not able to, for
    example, create our own implementation of CNM that worked without
    Swarm mode.
  2. We were unable to make the Rancher implementation of Docker volume
    plugin work reliably with the Docker daemon. I remember a
    particularly challenging issue,
    which caused the Docker daemon to lock up from time to time. We
    were not able to get this issue fixed, nor were we able to find a

We solved these problems in Rancher 1.2 (released December 2016) by
switching to Kubernetes Container Network Interface (CNI) and Kubernetes
Flexvolume storage framework. Since Rancher 2.0 builds on Kubernetes,
any networking, storage, load balancer, and security solutions that
integrate with Kubernetes now work with Rancher out of the

Container orchestration

We developed a container orchestrator for Rancher, called Cattle, to
add a number of features missing from early Docker Swarm, including
service discovery, DNS, service upgrade, and a load balancer. We hoped
Cattle would eventually be superseded by Swarm as Swarm becomes more
full featured.

When Rancher 1.0 was released in March 2016, however, Swarm was still not quite ready. At the
time, Kubernetes was also still immature and the future of container
orchestration was uncertain. Therefore, we decided that Rancher 1.0
should provide support for multiple orchestrators: Cattle, Swarm,
Kubernetes, and Mesos. Our users loved the idea of being able to adopt
one product without having to commit to a particular container

We were really excited in June 2016 when Docker announced Swarm Mode. Swarm Mode offered many
features missing from early Docker Swarm and was much closer to what
Cattle could do. We quickly added Swarm Mode support in

By early 2017, however, it became apparent that Swarm Mode was not gaining traction. Perhaps early Swarm
mode implementations had quality issues, or perhaps Kubernetes
development was already too far ahead. A vast majority of Rancher users
were selecting Cattle or Kubernetes.

Rancher 2.0 builds on the industry-standard Kubernetes orchestrator.
Cattle is not gone—we will continue to develop it as it is now part of
the integrated Rancher experience. With 2.0, we provide a simple Docker
and Docker Compose user experience that builds on Kubernetes. Anyone
with basic understanding of Docker can get started with Rancher quickly,
and move to the more advanced native Kubernetes experience when they are
ready to do so.

Container ecosystem

DockerCon Europe has an impressive list of sponsors, which are no doubt
attracted by the ever-growing number of Docker users. I always look for
the latest number of total pulls from DockerHub as a benchmark of Docker
growth. At DockerCon Austin in April 2017, that number was 12 billion,
and has no doubt grown since then.

The Kubernetes ecosystem consists of largely the same set of companies, but
the engagement model is quite different. Most ecosystem partners like us
view Docker as mature technology with a lot of users. The Kubernetes
ecosystem is far more vibrant because that’s where active development,
innovation, and integration is happening.

Where will Docker go?

I have no real insight on what Docker will announce this week. And
that’s why I find I am really looking forward to attending this
DockerCon. Will Docker announce something this week that motivates
ecosystem partners to increase development efforts on Docker? Are they
going to announce any new projects or

Looking at the original containerd

Solomon Hykes published in December of 2016, I noticed one particular

containerd will use the OCI

In the new containerd world, Docker is positioned at the same level
as OpenShift (and Rancher 2.0), at a layer even higher than Kubernetes.
Perhaps there will be a new Docker built on Kubernetes? I can’t wait to
find out.

Rancher at DockerCon

Please stop by our booth (G16) to say hello, get a demo of Rancher 2.0
and pick-up a coveted Rancher t-shirt. It would also be great to see
you in one of our speaking sessions:

Kubernetes for Docker Users Speaker: Darren Shepherd When: Tuesday,
17 October from 16:35 – 16:55 Where: Ecosystem B – Auditorium 12

Using LinuxKit to Build Custom RancherOS Systems Speaker: Sven
Dowideit When: Thursday, 19 October Where: Moby Summit

Sheng is a co-founder and CEO of Rancher Labs. Prior to starting
Rancher, Sheng was CTO of the Cloud Platforms group at Citrix Systems
after their acquisition of Cloud.com, where he was co-founder and CEO.
Sheng has more than 15 years of experience building innovative
technology. He was a co-founder at Teros, which was acquired by Citrix
in 2005 and led large engineering teams at SEVEN Networks, and Openwave
Systems. Sheng started his career as a Staff Engineer in Java Software
at Sun Microsystems, where he designed the Java Native Interface (JNI)
and led the Java Virtual Machine (JVM) development for the Java 2
platform. Sheng has a B.S. from the University of Science and Technology
of China and a Ph.D. from Yale University.

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