Overview

This page provides an overview of the Datadog CSI Driver and installation instructions on a Kubernetes cluster.

For more information about Kubernetes Container Storage Interface (CSI), see the Kubernetes CSI documentation.

The Datadog CSI Driver is open source.

How it works

The Datadog CSI Driver is a DaemonSet that runs a gRPC server implementing the CSI specifications on each node of your Kubernetes cluster.

Installing Datadog CSI driver on a Kubernetes cluster allows you to use CSI volumes by specifying the Datadog CSI driver’s name.

The Datadog CSI node server is responsible for managing Datadog CSI’s volume lifecycle.

Why use Datadog CSI Driver?

The Datadog CSI Driver allows the Datadog Agent to share the Trace Agent and DogStatsD Unix Domain Sockets with user pods regardless of the namespace pod security standards.

If CSI volumes are not used, the UDS sockets need to be shared with the user pod through hostpath volumes. If the user pod is running in a namespace that has non-privileged pod security standards, the pod fails to start because hostpath volumes are not permitted in that context.

The Datadog CSI Driver shifts the hostpath volume from the user application to the CSI node server: the CSI DaemonSet runs in a separate privileged namespace and allows injecting UDS sockets into user pods with a Datadog CSI volume, which allows user pods to run in namespaces with baseline or restricted pod security standards.

Installation and activation

helm repo add datadog https://helm.datadoghq.com
helm repo update

helm install datadog-agent datadog/datadog --set datadog.csi.enabled=true

Datadog CSI volumes

CSI volumes processed by the Datadog CSI Driver must have the following format:

csi:
    driver: k8s.csi.datadoghq.com
    volumeAttributes:
        type: <volume-type>
name: <volume-name>

For example:

apiVersion: v1
kind: Pod
metadata:
  name: pod-name
spec:
  containers:
    - name: ubuntu
      image: ubuntu
      command: ["/bin/bash", "-c", "--"]
      args: ["while true; do sleep 30; echo hello-ubuntu; done;"]
      volumeMounts:
        - mountPath: /var/sockets/apm/
          name: dd-csi-volume-apm-dir
        - mountPath: /var/sockets/dsd/dsd.sock
          name: dd-csi-volume-dsd
  volumes:
    - name: dd-csi-volume-dsd
      csi:
        driver: k8s.csi.datadoghq.com
        volumeAttributes:
          type: DSDSocket
    - name: dd-csi-volume-apm-dir
      csi:
        driver: k8s.csi.datadoghq.com
        volumeAttributes:
          type: APMSocketDirectory

Four types of CSI volume are supported:

• APMSocket
• APMSocketDirectory
• DSDSocket
• DSDSocketDirectory

APMSocket

This type is useful for mounting a Trace Agent UDS socket file.

For example:

csi:
    driver: k8s.csi.datadoghq.com
    volumeAttributes:
        type: APMSocket
name: datadog-apm

If the indicated socket doesn’t exist, the mount operation fails, and the pod is blocked in the ContainerCreating phase.

APMSocketDirectory

This type is useful for mounting the directory containing the APM socket.

For example:

csi:
    driver: k8s.csi.datadoghq.com
    readOnly: false
    volumeAttributes:
        type: APMSocketDirectory
name: datadog

DSDSocket

This type is useful for mounting a DogStatsD UDS socket file.

For example:

csi:
    driver: k8s.csi.datadoghq.com
    volumeAttributes:
        type: DSDSocket
name: datadog-dsd

If the indicated socket doesn’t exist, the mount operation fails, and the pod is blocked in the ContainerCreating phase.

DSDSocketDirectory

This type is useful for mounting the directory containing the DogStatsD socket.

For example:

csi:
    driver: k8s.csi.datadoghq.com
    readOnly: false
    volumeAttributes:
        type: DSDSocketDirectory
name: datadog

Security considerations

The Datadog CSI Driver requires elevated privileges and specific host access

Privileged security context

The Datadog CSI Driver must run as a privileged container to perform mount operations and access the host filesystem.

Access to /var/lib/kubelet/pods

The Datadog CSI Driver needs read-write access to the /var/lib/kubelet/pods directory because Kubernetes manages pod volumes using this directory. The Datadog CSI Driver must access /var/lib/kubelet/pods to inject Datadog Unix Domain Sockets into user pods.

Bidirectional mount propagation

Bidirectional mount propagation is required to ensure that volume mounts from the Datadog CSI node server are visible to both the host and the user pods. Without bidirectional mount propagation, the shared sockets cannot propagate correctly into pods.

By isolating the Datadog CSI Driver in a privileged namespace, Kubernetes clusters can safely share Datadog sockets with user pods running under strict Pod Security Standards like baseline or restricted, while minimizing security risks.

Further reading

Additional helpful documentation, links, and articles:

Bring high-performance observability to secure Kubernetes environments with Datadog's CSI driverBLOG