List All Container Images Running in a Cluster

This page shows how to use kubectl to list all of the Container images for Pods running in a cluster.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

• iximiuz Labs
• Killercoda
• KodeKloud
• Play with Kubernetes

To check the version, enter kubectl version.

In this exercise you will use kubectl to fetch all of the Pods running in a cluster, and format the output to pull out the list of Containers for each.

List all Container images in all namespaces

• Fetch all Pods in all namespaces using kubectl get pods --all-namespaces
• Format the output to include only the list of Container image names using -o jsonpath={.items[*].spec['initContainers', 'containers'][*].image}. This will recursively parse out the image field from the returned json.
  • See the jsonpath reference for further information on how to use jsonpath.
• Format the output using standard tools: tr, sort, uniq
  • Use tr to replace spaces with newlines
  • Use sort to sort the results
  • Use uniq to aggregate image counts

kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec['initContainers', 'containers'][*].image}" |\
tr -s '[[:space:]]' '\n' |\
sort |\
uniq -c

The jsonpath is interpreted as follows:

• .items[*]: for each returned value
• .spec: get the spec
• ['initContainers', 'containers'][*]: for each container
• .image: get the image

List Container images by Pod

The formatting can be controlled further by using the range operation to iterate over elements individually.

kubectl get pods --all-namespaces -o jsonpath='{range .items[*]}{"\n"}{.metadata.name}{":\t"}{range .spec.containers[*]}{.image}{", "}{end}{end}' |\
sort

List Container images filtering by Pod label

To target only Pods matching a specific label, use the -l flag. The following matches only Pods with labels matching app=nginx.

kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec.containers[*].image}" -l app=nginx

List Container images filtering by Pod namespace

To target only pods in a specific namespace, use the namespace flag. The following matches only Pods in the kube-system namespace.

kubectl get pods --namespace kube-system -o jsonpath="{.items[*].spec.containers[*].image}"

List Container images using a go-template instead of jsonpath

As an alternative to jsonpath, Kubectl supports using go-templates for formatting the output:

kubectl get pods --all-namespaces -o go-template --template="{{range .items}}{{range .spec.containers}}{{.image}} {{end}}{{end}}"

What's next

Reference

• Jsonpath reference guide
• Go template reference guide