What version of Docker is my Kubernetes running on? - kubernetes

Question

Kubernetes uses Docker, and kubelet dictates the compatible Docker versions for any given cluster.
My question is, given a Kubernetes cluster that is already configured and running, how would I find out what version of Docker is running in the cluster if I don't have direct access to the nodes?

Answer 1

You can find container runtime and its version using the following:
kubectl get node <node> -o jsonpath="{.status.nodeInfo.containerRuntimeVersion}"

Answer 2

The following kubectl command will show detail information of the nodes in the cluster:
kubectl describe nodes
One instance of a node is shown below:
Name: node3-virtualbox
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/hostname=node3-virtualbox
Annotations: node.alpha.kubernetes.io/ttl=0
volumes.kubernetes.io/controller-managed-attach-detach=true
Taints: <none>
CreationTimestamp: Tue, 05 Dec 2017 07:01:42 +0100
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
OutOfDisk False Tue, 05 Dec 2017 22:52:05 +0100 Tue, 05 Dec 2017 17:08:13 +0100 KubeletHasSufficientDisk kubelet has sufficient disk space available
MemoryPressure False Tue, 05 Dec 2017 22:52:05 +0100 Tue, 05 Dec 2017 21:08:21 +0100 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Tue, 05 Dec 2017 22:52:05 +0100 Tue, 05 Dec 2017 21:08:21 +0100 KubeletHasNoDiskPressure kubelet has no disk pressure
Ready False Tue, 05 Dec 2017 22:52:05 +0100 Tue, 05 Dec 2017 21:08:21 +0100 KubeletNotReady runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
Addresses:
InternalIP: 10.0.2.15
Hostname: node3-virtualbox
Capacity:
cpu: 1
memory: 2048268Ki
pods: 110
Allocatable:
cpu: 1
memory: 1945868Ki
pods: 110
System Info:
Machine ID: 9654f9402bfc4042b82b454e323cf46c
System UUID: 6EBA3E13-624C-4C82-A8EA-24FF86FA6E66
Boot ID: c7217654-8514-482c-9899-f04a3d3ce6d8
Kernel Version: 4.4.0-101-generic
OS Image: Ubuntu 16.04.1 LTS
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://1.13.1
Kubelet Version: v1.8.4
Kube-Proxy Version: v1.8.4
ExternalID: node3-virtualbox
Non-terminated Pods: (2 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits
--------- ---- ------------ ---------- --------------- -------------
kube-system kube-proxy-sxp5s 0 (0%) 0 (0%) 0 (0%) 0 (0%)
kube-system weave-net-6jf98 20m (2%) 0 (0%) 0 (0%) 0 (0%)
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
CPU Requests CPU Limits Memory Requests Memory Limits
------------ ---------- --------------- -------------
20m (2%) 0 (0%) 0 (0%) 0 (0%)
Events: <none>
The docker version running on the nodes can be found in system info:, for example in above case:
Container Runtime Version: docker://1.13.1

Answer 3

try kubectl get nodes -o wide and check CONTAINER-RUNTIME column, here my AKS example:
t#Azure:/$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
aks-agentpool-311111-0 Ready agent 4d1h v1.12.8 10.240.0.66 <none> Ubuntu 16.04.6 LTS 4.15.0-1042-azure docker://3.0.4
aks-agentpool-311111-1 Ready agent 4d v1.12.8 10.240.0.35 <none> Ubuntu 16.04.6 LTS 4.15.0-1042-azure docker://3.0.4
aks-agentpool-311111-3 Ready agent 4d1h v1.12.8 10.240.0.97 <none> Ubuntu 16.04.6 LTS 4.15.0-1042-azure docker://3.0.4