Amazon EKS ended support for Dockershim - Amazon EKS

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Amazon EKS ended support for Dockershim

Kubernetes no longer supports Dockershim. The Kubernetes team removed the runtime in Kubernetes version 1.24. For more information, see Kubernetes is Moving on From Dockershim: Commitments and Next Steps on the Kubernetes Blog.

Amazon EKS also ended support for Dockershim starting with the Kubernetes version 1.24 release. Amazon EKS AMIs that are officially published have containerd as the only runtime starting with version 1.24. This topic covers some details, but more information is available in All you need to know about moving to containerd on Amazon EKS.

There's a kubectl plugin that you can use to see which of your Kubernetes workloads mount the Docker socket volume. For more information, see Detector for Docker Socket (DDS) on GitHub. Amazon EKS AMIs that run Kubernetes versions that are earlier than 1.24 use Docker as the default runtime. However, these Amazon EKS AMIs have a bootstrap flag option that you can use to test out your workloads on any supported cluster using containerd. For more information, see Test migration from Docker to containerd.

We will continue to publish AMIs for existing Kubernetes versions until the end of their support date. For more information, see Amazon EKS Kubernetes release calendar. If you require more time to test your workloads on containerd, use a supported version before 1.24. But, when you want to upgrade official Amazon EKS AMIs to version 1.24 or later, make sure to validate that your workloads run on containerd.

The containerd runtime provides more reliable performance and security. containerd is the runtime that's being standardized on across Amazon EKS. Fargate and Bottlerocket already use containerd only. containerd helps to minimize the number of Amazon EKS AMI releases that are required to address Dockershim Common Vulnerabilities and Exposures (CVEs). Because Dockershim already uses containerd internally, you might not need to make any changes. However, there are some situations where changes might or must be required:

  • You must make changes to applications that mount the Docker socket. For example, container images that are built with a container are impacted. Many monitoring tools also mount the Docker socket. You might need to wait for updates or re-deploy workloads for runtime monitoring.

  • You might need to make changes for applications that are reliant on specific Docker settings. For example, the HTTPS_PROXY protocol is no longer supported. You must update applications that use this protocol. For more information, see dockerd in the Docker Docs.

  • If you use the Amazon ECR credential helper to pull images, you must switch to the kubelet image credential provider. For more information, see Configure a kubelet image credential provider in the Kubernetes documentation.

  • Because Amazon EKS 1.24 no longer supports Docker, some flags that the Amazon EKS bootstrap script previously supported are no longer supported. Before moving to Amazon EKS 1.24 or later, you must remove any reference to flags that are now unsupported:

    • --container-runtime dockerd (containerd is the only supported value)

    • --enable-docker-bridge

    • --docker-config-json

  • If you already have Fluentd configured for Container Insights, then you must migrate Fluentd to Fluent Bit before changing to containerd. The Fluentd parsers are configured to only parse log messages in JSON format. Unlike dockerd, the containerd container runtime has log messages that aren't in JSON format. If you don't migrate to Fluent Bit, some of the configured Fluentd's parsers will generate a massive amount of errors inside the Fluentd container. For more information on migrating, see Set up Fluent Bit as a DaemonSet to send logs to CloudWatch Logs.

  • If you use a custom AMI and you are upgrading to Amazon EKS 1.24, then you must make sure that IP forwarding is enabled for your worker nodes. This setting wasn't needed with Docker but is required for containerd. It is needed to troubleshoot Pod-to-Pod, Pod-to-external, or Pod-to-apiserver network connectivity.

    To verify this setting on a worker node, run either of the following commands:

    • sysctl net.ipv4.ip_forward

    • cat /proc/sys/net/ipv4/ip_forward

    If the output is 0, then run either of the following commands to activate the net.ipv4.ip_forward kernel variable:

    • sysctl -w net.ipv4.ip_forward=1

    • echo 1 > /proc/sys/net/ipv4/ip_forward

    For the setting's activation on Amazon EKS AMIs in the containerd runtime, see on GitHub.