Below you will find pages that utilize the taxonomy term “Kubectl”

Posts

List cluster's images

Kubernetes documentation provides this example but I prefer:

FILTER="{range .items[*].spec['initContainers', 'containers'][*]}{.image}{'\n'}{end}"
CONTEXT="..."

kubectl get pods \
--all-namespaces \
--output=jsonpath="${FILTER} \
--context="${CONTEXT}" \
| sort | uniq -c
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Posts

kubectl patch'ing keys containing forward slash

I wanted to use kubectl to (JSON) patch an Ingress. The value needing patching is an annotation tailscale.com/funnel.

TL;DR The Stack overflow answer has the solution: replace / with ~1

With apologies for using YAML instead of JSON:

Ingress:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    tailscale.com/funnel: "true"

The solution becomes:

VALUE="true" # Or "false"

# Pretty-printed for clarity
PATCH="
[
    {
        'op':'replace',
        'path':'/metadata/annotations/tailscale.com~1funnel',
        'value':'${VALUE}'
    }
]"

kubectl patch ingress/${INGRESS} \
--namespace=${NAMESPACE} \
--context=${CONTEXT} \
--type=json \
--patch="${PATCH}"
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Posts

`kubectl` auth changes in GKE v1.25

I was prompted by a question on Stack overflow “How to remove warning in kubectl with gcp auth plugin?” to try this new mechanism for myself. It’s described by Google in the a post Here’s what to know about changes to kubectl authentciation coming in GKE v1.25.

One question I’d not considered is: how is the change manifest? Thinking about it, I realized it’s probably evident in the users section of kubectl config. A long time, I wrote a blog post Kubernetes Engine: kubectl config that explains how kubectl leverages (!) gcloud to get an access token for GKE.

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Posts

`kubectl get events` 

NAMESPACE=test

kubectl create namespace ${NAMESPACE}

kubectl create deployment kuard \
--image=gcr.io/kuar-demo/kuard-amd64:blue \
--port=8080 \
--namespace=${NAMESPACE}

Typically, I’d then use kubectl describe pod to check the Events section for any issues:

kubectl describe pod \
--selector=app=kuard \
--namespace=test

But, from the Pod’s name (without the pod/ prefix), you can:

NAME=$(\
  kubectl get pod \
  --selector=app=kuard \
  --namespace=test \
  --output=name) && \
NAME=${NAME#pod/} && \
echo ${NAME}

kubectl get events \
--field-selector=involvedObject.name=${NAME} \
--namespace=${NAMESPACE} \
--output=jsonpath='{range .items[*]}{.message}{"\n"}{end}'

NOTE range‘ing over the items permits adding newlines (\n) after each entry. Using {.items[*].message} yields a less manageable result.

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