Docker support deprecated in Kubernetes will break your clusters, says CNCF ambassador. It's only the runtime, says Docker

Admins have until late 2021 to move away, but Windows containers need caution

"Docker support is being deprecated in Kubernetes. You need to pay attention to this and plan for it. THIS WILL BREAK YOUR CLUSTERS," said CNCF Ambassador Ian Coldwater on Twitter.

This caused consternation among developers but it is admins who need to take note – Kubernetes will still run Docker containers.

Coldwater's tweet was intended to attract attention, and it did. Docker containers are everywhere and embedded in modern application development and deployment. What is going on?

The problem is that "Docker" means different things in different contexts. The release notes for the forthcoming Kubernetes 1.20 state:

Docker support in the kubelet is now deprecated and will be removed in a future release. The kubelet uses a module called "dockershim" which implements CRI support for Docker and it has seen maintenance issues in the Kubernetes community. We encourage you to evaluate moving to a container runtime that is a full-fledged implementation of CRI (v1alpha1 or v1 compliant) as they become available.

CRI stands for Container Runtime Interface, an API to the runtime that (among other things) starts and stops containers. Docker is a container runtime but it does not implement CRI, hence the need for the shim mentioned in the release notes. It is better to use alternative runtimes such as containerd or CRI-O. Docker itself uses containerd, wrapped with additional features useful in development but generally not required by Kubernetes.

"Developers can still use Docker to build images, no change there," a Docker spokesperson told us. "This primarily impacts ops/admins using Docker Engine for runtime as Kubernetes will just use containerd to run them instead. They will need to transition to using containerd as the container runtime for their Kubernetes clusters. Docker Engine is containerd with some extra stuff like UX that developers don't really need for Kubernetes anyway. This streamlining is good news as containerd now becomes a core for both Docker and for Kubernetes."

Note also that Kubernetes 1.20 still supports Docker. A hasty FAQ on the subject says that "the only thing changing in 1.20 is a single warning log printed at kubelet startup if using Docker as the runtime." The earliest release without dockershim "would be 1.23 in late 2021," said the team.


Docker finally enforces pull rate limits, but reckons only 1.5% of users are affected


That said, there are some issues with changing from Docker to a different runtime. The above FAQ has a list, including logging configuration, node provisioning scripts, Kubectl (command-line tool for Kubernetes) plugins that may require Docker, and integration with GPUs or other special hardware.

It is not mentioned in the FAQ, but there is also an issue with Windows containers. Up until Kubernetes 1.18, Docker was "the only supported container runtime for Windows," as explained in this post. In 1.18, containerd support was added but is alpha quality, so not intended for production use. As of now, "Docker EE-basic 19.03+ is the recommended container runtime for all Windows Server versions. This works with the dockershim code included in the kubelet," state the docs, though "ContainerD 1.4.0-beta.2+ can also be used as the container runtime for Windows Kubernetes nodes." ContainerD Windows support has a "stable release target" for Kubernetes 1.20 or later. The message for those using Windows containers is not to be hasty about switching.

"Fascinating how this docker/docker-shim deprecation has created mass confusion," said VMware's Joe Beda, a co-founder of Kubernetes; while Coldwater reflected: "I'm sorry I caused panic this morning. I wanted to call attention to the deprecation of Docker support in advance so people could make a plan for it, because for some it will be a major breaking change that will take time to fix. It, uh, worked? But it also stressed people out." ®

Similar topics

Other stories you might like

  • Warehouse belonging to Chinese payment terminal manufacturer raided by FBI

    PAX Technology devices allegedly infected with malware

    US feds were spotted raiding a warehouse belonging to Chinese payment terminal manufacturer PAX Technology in Jacksonville, Florida, on Tuesday, with speculation abounding that the machines contained preinstalled malware.

    PAX Technology is headquartered in Shenzhen, China, and is one of the largest electronic payment providers in the world. It operates around 60 million point-of-sale (PoS) payment terminals in more than 120 countries.

    Local Jacksonville news anchor Courtney Cole tweeted photos of the scene.

    Continue reading
  • Everything you wanted to know about modern network congestion control but were perhaps too afraid to ask

    In which a little unfairness can be quite beneficial

    Systems Approach It’s hard not to be amazed by the amount of active research on congestion control over the past 30-plus years. From theory to practice, and with more than its fair share of flame wars, the question of how to manage congestion in the network is a technical challenge that resists an optimal solution while offering countless options for incremental improvement.

    This seems like a good time to take stock of where we are, and ask ourselves what might happen next.

    Congestion control is fundamentally an issue of resource allocation — trying to meet the competing demands that applications have for resources (in a network, these are primarily link bandwidth and router buffers), which ultimately reduces to deciding when to say no and to whom. The best framing of the problem I know traces back to a paper [PDF] by Frank Kelly in 1997, when he characterized congestion control as “a distributed algorithm to share network resources among competing sources, where the goal is to choose source rate so as to maximize aggregate source utility subject to capacity constraints.”

    Continue reading
  • How business makes streaming faster and cheaper with CDN and HESP support

    Ensure a high video streaming transmission rate

    Paid Post Here is everything about how the HESP integration helps CDN and the streaming platform by G-Core Labs ensure a high video streaming transmission rate for e-sports and gaming, efficient scalability for e-learning and telemedicine and high quality and minimum latencies for online streams, media and TV broadcasters.

    HESP (High Efficiency Stream Protocol) is a brand new adaptive video streaming protocol. It allows delivery of content with latencies of up to 2 seconds without compromising video quality and broadcasting stability. Unlike comparable solutions, this protocol requires less bandwidth for streaming, which allows businesses to save a lot of money on delivery of content to a large audience.

    Since HESP is based on HTTP, it is suitable for video transmission over CDNs. G-Core Labs was among the world’s first companies to have embedded this protocol in its CDN. With 120 points of presence across 5 continents and over 6,000 peer-to-peer partners, this allows a service provider to deliver videos to millions of viewers, to any devices, anywhere in the world without compromising even 8K video quality. And all this comes at a minimum streaming cost.

    Continue reading
  • Cisco deprecates Microsoft management integrations for UCS servers

    Working on Azure integration – but not there yet

    Cisco has deprecated support for some third-party management integrations for its UCS servers, and emerged unable to play nice with Microsoft's most recent offerings.

    Late last week the server contender slipped out an end-of-life notice [PDF] for integrations with Microsoft System Center's Configuration Manager, Operations Manager, and Virtual Machine Manager. Support for plugins to VMware vCenter Orchestrator and vRealize Orchestrator have also been taken out behind an empty rack with a shotgun.

    The Register inquired about the deprecations, and has good news and bad news.

    Continue reading
  • Protonmail celebrates Swiss court victory exempting it from telco data retention laws

    Doesn't stop local courts' surveillance orders, though

    Encrypted email provider Protonmail has hailed a recent Swiss legal ruling as a "victory for privacy," after winning a lawsuit that sees it exempted from data retention laws in the mountainous realm.

    Referring to a previous ruling that exempted instant messaging services from data capture and storage laws, the Protonmail team said this week: "Together, these two rulings are a victory for privacy in Switzerland as many Swiss companies are now exempted from handing over certain user information in response to Swiss legal orders."

    Switzerland's Federal Administrative Court ruled on October 22 that email providers in Switzerland are not considered telecommunications providers under Swiss law, thereby removing them from the scope of data retention requirements imposed on telcos.

    Continue reading
  • Japan picks AWS and Google for first gov cloud push

    Local players passed over for Digital Agency’s first project

    Japan's Digital Agency has picked Amazon Web Services and Google Cloud for its first big reform push.

    The Agency started operations in September 2021, years after efforts like the UK's Government Digital Service (GDS) or Australia's Digital Transformation Agency (DTA). The body was a signature reform initiated by Prime Minister Yoshihide Suga, who spent his year-long stint in the top job trying to curb Japan's reliance on paper documents, manual processes, and faxes. Japan's many government agencies also operated their websites independently of each other, most with their own design and interface.

    The new Agency therefore has a remit to "cut across all ministries" and "provide services that are driven not toward ministries, agency, laws, or systems, but toward users and to improve user-experience".

    Continue reading
  • Singaporean minister touts internet 'kill switch' that finds kids reading net nasties and cuts 'em off ASAP

    Fancies a real-time crowdsourced content rating scheme too

    A Minister in the Singapore government has suggested the creation of an internet kill switch that would prevent minors from reading questionable material online – perhaps using ratings of content created in real time by crowdsourced contributors.

    "The post-COVID world will bring new challenges globally, including to us in the security arena," said Minister for Defence Dr Ng Eng Hen at a Tuesday ceremony to award the city-state's 2021 Defense Technology Prize.

    "For operations, the SAF (Singapore Armed Force) has to expand its capabilities in the digital domain. Whether for administrative or operational purposes, I think that we will need to leverage technology to the maximum," he declared.

    Continue reading
  • China Telecom booted out of USA as Feds worry it could disrupt or spy on local networks

    FCC urges more action against Huawei and DJI, too

    The US Federal Communications Commission (FCC) has terminated China Telecom's authority to provide communications services in the USA.

    In its announcement of the termination, the government agency explained the decision is necessary because the national security environment has changed in the years since 2002. That was when China Telecom was first allowed to operate in the USA.

    The FCC now believes – partly based on classified advice from national security agencies – that China Telecom can "access, store, disrupt, and/or misroute US communications, which in turn allow them to engage in espionage and other harmful activities against the United States." And because China Telecom is state-controlled, China's government can compel the carrier to act as it sees fit, without judicial review or oversight.

    Continue reading

Biting the hand that feeds IT © 1998–2021