developer-guy / kubectl-detector-for-docker-socket

A Kubectl plugin that can detect if any of your workloads or manifest files are mounting the docker.sock volume

Detector for Docker Socket (DDS)

A kubectl plugin to detect if active Kubernetes workloads are mounting the docker socket (docker.sock) volume.

Install

Install the plugin with

krew install dds

How it works

dds looks for every pod in your Kubernetes cluster. If pods are part of a workload (eg Deployment, StatefulSet) it inspects the workload type instead of pods directly.

It then inspects all of the volumes in the containers and looks for any volume with the path *docker.sock

Supported workload types:

• Pods
• Deployments
• StatefulSets
• DaemonSets
• Jobs
• CronJobs

Run

You can run the plugin with no arguments and it will inspect all pods in all namespaces that the current Kubernetes user has access to.

kubectl dds

example output

NAMESPACE       TYPE            NAME                    STATUS
default         deployment      deploy-docker-volume    mounted
default         daemonset       ds-docker-volume        mounted
default         statefulset     ss-docker-volume        mounted
default         job             job-docker-volume       mounted
default         cron            cron-docker-volume      mounted
kube-system     pod             pod-docker-volume       mounted
test1           deployment      deploy-docker-volume    mounted

You can specify a namespace to limit the scope of what will be scanned.

kubectl dds --namespace kube-system

example output

NAMESPACE       TYPE    NAME                    STATUS
kube-system     pod     pod-docker-volume       mounted

You can run dds against a single manifest file or folder of manifest files (recursive). The repo includes a test/manifests directory.

kubectl dds --filename test

example output

FILE                                                    LINE    STATUS
test/manifests/docker-volume.cronjob.yaml               22      mounted
test/manifests/docker-volume.daemonset.yaml             24      mounted
test/manifests/docker-volume.deploy.test1.yaml          32      mounted
test/manifests/docker-volume.deploy.yaml                25      mounted
test/manifests/docker-volume.job.yaml                   17      mounted
test/manifests/docker-volume.pod.kube-system.yaml       14      mounted
test/manifests/docker-volume.statefulset.yaml           26      mounted

Use the --verbose flag to see all scanned workloads/files

kubectl dds --verbose

example output

NAMESPACE       TYPE            NAME                    STATUS
default         deployment      deploy-docker-volume    mounted
default         daemonset       ds-docker-volume        mounted
default         statefulset     ss-docker-volume        mounted
default         job             job-docker-volume       mounted
default         cron            cron-docker-volume      mounted
kube-system     pod             pod-docker-volume       mounted
kube-system     daemonset       aws-node                not-mounted
kube-system     daemonset       ebs-csi-node            not-mounted
kube-system     daemonset       kube-proxy              not-mounted
test1           deployment      deploy-docker-volume    mounted

You can use dds as part of your CI pipeline to catch manifest files before they are deployed.

kubectl dds --exit-with-error -f YOUR_FILES

If the docker.sock volume is found in any files the cli exit code with be 1.

Build

To build the binary you can use make dsd or go build -o kubectl-dds main.go

Install the kubectl-dds binary somewhere in your path to use it with kubectl or use it by itself without kubectl. The same kubectl authentication works with or without kubectl (e.g. $HOME/.kube/config or KUBECONFIG).

Testing

There are different test workloads in the /tests folder. You can deploy these workloads to verify the plugin is working as intended.

kubectl apply -f tests/
daemonset.apps/ds-docker-volume created
namespace/test1 created
deployment.apps/deploy-docker-volume created
deployment.apps/deploy-docker-volume created
job.batch/job-docker-volume created
pod/pod-docker-volume created
statefulset.apps/ss-docker-volume created
pod/empty-volume created
deployment.apps/no-volume created

and then run

kubectl dds
NAMESPACE       TYPE            NAME                    STATUS
default         deployment      deploy-docker-volume    mounted
default         daemonset       ds-docker-volume        mounted
default         statefulset     ss-docker-volume        mounted
default         job             job-docker-volume       mounted
default         cron            cron-docker-volume      mounted
kube-system     pod             pod-docker-volume       mounted
test1           deployment      deploy-docker-volume    mounted