Migrating telemetry and security agents from dockershim

Kubernetes' support for direct integration with Docker Engine is deprecated and has been removed. Most apps do not have a direct dependency on runtime hosting containers. However, there are still a lot of telemetry and monitoring agents that have a dependency on Docker to collect containers metadata, logs, and metrics. This document aggregates information on how to detect these dependencies as well as links on how to migrate these agents to use generic tools or alternative runtimes.

Telemetry and security agents

Within a Kubernetes cluster there are a few different ways to run telemetry or security agents. Some agents have a direct dependency on Docker Engine when they run as DaemonSets or directly on nodes.

Why do some telemetry agents communicate with Docker Engine?

Historically, Kubernetes was written to work specifically with Docker Engine. Kubernetes took care of networking and scheduling, relying on Docker Engine for launching and running containers (within Pods) on a node. Some information that is relevant to telemetry, such as a pod name, is only available from Kubernetes components. Other data, such as container metrics, is not the responsibility of the container runtime. Early telemetry agents needed to query the container runtime and Kubernetes to report an accurate picture. Over time, Kubernetes gained the ability to support multiple runtimes, and now supports any runtime that is compatible with the container runtime interface.

Some telemetry agents rely specifically on Docker Engine tooling. For example, an agent might run a command such as docker ps or docker top to list containers and processes or docker logs to receive streamed logs. If nodes in your existing cluster use Docker Engine, and you switch to a different container runtime, these commands will not work any longer.

Identify DaemonSets that depend on Docker Engine

If a pod wants to make calls to the dockerd running on the node, the pod must either:

• mount the filesystem containing the Docker daemon's privileged socket, as a volume; or
• mount the specific path of the Docker daemon's privileged socket directly, also as a volume.

For example: on COS images, Docker exposes its Unix domain socket at /var/run/docker.sock This means that the pod spec will include a hostPath volume mount of /var/run/docker.sock.

Here's a sample shell script to find Pods that have a mount directly mapping the Docker socket. This script outputs the namespace and name of the pod. You can remove the grep '/var/run/docker.sock' to review other mounts.

kubectl get pods --all-namespaces \
-o=jsonpath='{range .items[*]}{"\n"}{.metadata.namespace}{":\t"}{.metadata.name}{":\t"}{range .spec.volumes[*]}{.hostPath.path}{", "}{end}{end}' \
| sort \
| grep '/var/run/docker.sock'

Detecting Docker dependency from node agents

If your cluster nodes are customized and install additional security and telemetry agents on the node, check with the agent vendor to verify whether it has any dependency on Docker.

Telemetry and security agent vendors

This section is intended to aggregate information about various telemetry and security agents that may have a dependency on container runtimes.

We keep the work in progress version of migration instructions for various telemetry and security agent vendors in Google doc. Please contact the vendor to get up to date instructions for migrating from dockershim.

Migration from dockershim

Aqua

No changes are needed: everything should work seamlessly on the runtime switch.

Datadog

How to migrate: Docker deprecation in Kubernetes The pod that accesses Docker Engine may have a name containing any of:

• datadog-agent
• datadog
• dd-agent

Dynatrace

How to migrate: Migrating from Docker-only to generic container metrics in Dynatrace

Containerd support announcement: Get automated full-stack visibility into containerd-based Kubernetes environments

CRI-O support announcement: Get automated full-stack visibility into your CRI-O Kubernetes containers (Beta)

The pod accessing Docker may have name containing:

• dynatrace-oneagent

Falco

How to migrate:

Migrate Falco from dockershim Falco supports any CRI-compatible runtime (containerd is used in the default configuration); the documentation explains all details. The pod accessing Docker may have name containing:

• falco

Prisma Cloud Compute

Check documentation for Prisma Cloud, under the "Install Prisma Cloud on a CRI (non-Docker) cluster" section. The pod accessing Docker may be named like:

• twistlock-defender-ds

SignalFx (Splunk)

The SignalFx Smart Agent (deprecated) uses several different monitors for Kubernetes including kubernetes-cluster, kubelet-stats/kubelet-metrics, and docker-container-stats. The kubelet-stats monitor was previously deprecated by the vendor, in favor of kubelet-metrics. The docker-container-stats monitor is the one affected by dockershim removal. Do not use the docker-container-stats with container runtimes other than Docker Engine.

How to migrate from dockershim-dependent agent:

1. Remove docker-container-stats from the list of configured monitors. Note, keeping this monitor enabled with non-dockershim runtime will result in incorrect metrics being reported when docker is installed on node and no metrics when docker is not installed.
2. Enable and configure kubelet-metrics monitor.

The Pod accessing Docker may be named something like:

• signalfx-agent

Yahoo Kubectl Flame

Flame does not support container runtimes other than Docker. See https://github.com/yahoo/kubectl-flame/issues/51