Kubernetes

[AlanGreene]

To test / review / consider:

• Lens, 'the Kubernetes IDE': https://github.com/lensapp/lens

The following may be more suited to a homelab repo, ref. #50

• Alternative dashboards
  • https://github.com/vmware-tanzu/octant
  • https://github.com/KubeHelper/kubehelper
  • https://github.com/skooner-k8s/skooner
  • https://github.com/kubenav/kubenav (includes mobile app)
• Setup / install tools
  • https://k3s.io/
  • https://github.com/alexellis/k3sup
  • https://k3d.io/ (brew install k3d)
  • https://github.com/alexellis/arkade

[AlanGreene]

Get the name of the all the nodes’ name, os image, os architecture, pod cidrs, internal and external ip address

kubectl get nodes -o custom-columns='NODE-NAME:.metadata.name,OS-IMAGE:.status.nodeInfo.osImage,OS-ARCH:.status.nodeInfo.architecture,POD-CIDRs:.spec.podCIDRs[*],INTERNAL-IP:.status.addresses[?(@.type=="InternalIP")].address,EXTERNAL-IP:.status.addresses[?(@.type=="ExternalIP")].address'

which shows:

NODE-NAME               OS-IMAGE             OS-ARCH   POD-CIDRs       INTERNAL-IP    EXTERNAL-IP
sideling1.example.com   Ubuntu 20.04.2 LTS   amd64     10.244.0.0/24   10.51.10.109   <none>
sideling2.example.com   Ubuntu 20.04.2 LTS   amd64     10.244.1.0/24   10.51.12.45    <none>

---

Get all the pods that are using specific configmap. Change the configmap name according to your requirement in @.spec.volumes[*].configMap.name=="test-config"

which worked for me using the coredns configMap.

First I queried for configMaps on my cluster: -

kubectl get configmaps -A

NAMESPACE         NAME                                 DATA   AGE
default           kube-root-ca.crt                     1      57d
kube-node-lease   kube-root-ca.crt                     1      57d
kube-public       cluster-info                         1      57d
kube-public       kube-root-ca.crt                     1      57d
kube-system       calico-config                        4      57d
kube-system       coredns                              1      57d
kube-system       extension-apiserver-authentication   6      57d
kube-system       kube-proxy                           2      57d
kube-system       kube-root-ca.crt                     1      57d
kube-system       kubeadm-config                       2      57d
kube-system       kubelet-config-1.21                  1      57d

and then for Pods using that particular configMap: -

kubectl get pods --all-namespaces -o jsonpath='{range $.items[?(@.spec.volumes[*].configMap.name=="coredns")]}{.metadata.name}{"\t"}{.spec.volumes[*].configMap.name}{"\n"}{end}'

coredns-558bd4d5db-dmnnc	coredns
coredns-558bd4d5db-t8xnm	coredns

---

Get the name of the all the nodes and their corresponding InternalIP address.

kubectl get nodes -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.addresses[?(@.type=="InternalIP")].address}{"\n"}{end}'

sideling1.example.com	10.51.10.109
sideling2.example.com	10.51.12.45

---

Get all the pods that are on specific node. Change the node name accordingly

kubectl get pods --all-namespaces -o jsonpath='{range $.items[?(@.spec.nodeName=="sideling1.example.com")]}{.metadata.name}{"\t"}{.spec.nodeName}{"\n"}{end}'

calico-kube-controllers-cc8959d7f-9qhh4	sideling1.example.com
calico-node-kwj42	sideling1.example.com
coredns-558bd4d5db-dmnnc	sideling1.example.com
coredns-558bd4d5db-t8xnm	sideling1.example.com
etcd-sideling1.example.com	sideling1.example.com
kube-apiserver-sideling1.example.com	sideling1.example.com
kube-controller-manager-sideling1.example.com	sideling1.example.com
kube-proxy-kz2cm	sideling1.example.com
kube-scheduler-sideling1.example.com	sideling1.example.com

kubectl get pods --all-namespaces -o jsonpath='{range $.items[?(@.spec.nodeName=="sideling2.example.com")]}{.metadata.name}{"\t"}{.spec.nodeName}{"\n"}{end}'

calico-node-jd867	sideling2.example.com
kube-proxy-bc897	sideling2.example.com

[AlanGreene]

Including colima as replacement for Docker Desktop, and additional steps for docker CLI here too…

brew install colima docker docker-buildx
mkdir -p ~/.docker/cli-plugins
ln -sfn $HOMEBREW_PREFIX/opt/docker-buildx/bin/docker-buildx ~/.docker/cli-plugins/docker-buildx

colima start --cpu 2 --memory 4

Should be sufficient for a basic working environment in which to run kind etc.

colima start --edit to save changes to a config file

brew services start colima to run on system startup

[AlanGreene]

https://headlamp.dev/
in particular see https://headlamp.dev/docs/latest/development/plugins/functionality
(similar approach could also be useful for resurrecting some of the previous Dashboard extension functionality)

[AlanGreene]

Starship auto-enable Kubernetes prompt:
https://github.com/starship/starship/issues/840#issuecomment-2771340433

[kubernetes]
disabled = false
format = '[$symbol$context \($namespace\) $symbol]($style)'
detect_env_vars = ["KUBIE_ACTIVE"]
detect_files = ["kubectx"]
style = 'blue bold'

[AlanGreene]

Disable cronjobs:
kubectl get cronjobs | grep nightly-release | grep False | cut -d' ' -f 1 | xargs kubectl patch cronjobs -p '{"spec": {"suspend": true }}'

[AlanGreene]

kubectl --sort-by=.metadata.creationTimestamp

[AlanGreene]

https://github.com/sbstp/kubie
alternative to kubectx, kubens, and more

[AlanGreene]

SelfSubjectReview
k auth whoami

SelfSubjectAccessReviews
k auth can-i …

[AlanGreene]

k get --raw /metrics | grep tekton

[AlanGreene]

kubectl user preferences (kuberc):
https://kubernetes.io/docs/reference/kubectl/kuberc/

Temporarily disable with export KUBERC=off

apiVersion: kubectl.config.k8s.io/v1beta1
kind: Preference
aliases:
  - name: crns
    command: create namespace
  - name: getn
    command: get
#    options:
#      - name: output
#        default: json
    prependArgs:
      - namespace
  - name: j
    command: get
    options:
      - name: output
        default: json
  - name: shell
    # k run alpine-shell --image=alpine -i -t --rm -- sh
    command: run
    options:
      - name: image
        default: alpine
    appendArgs:
      - sh
    prependArgs:
      - alpine-shell
      - -it
      - --rm
  - name: "y"
    command: get
    options:
      - name: output
        default: yaml
defaults:
  - command: apply
    options:
      - name: server-side
        default: "true"
  - command: delete
    options:
      - name: interactive
        default: "true"
  - command: get
    options:
      - name: output
        default: wide

[AlanGreene]

alias kk='kubectl apply -k'
alias krun='kubectl run --rm --restart=Never --image-pull-policy=IfNotPresent -i -t'

[AlanGreene]

k-pods-labels() {
  params=($*)
  k get pods --all-namespaces --show-labels |grep "$1"
}

[AlanGreene]

k-events() {
  params=($*)
  k get ev -o=custom-columns=Name:metadata.name,Reason:reason,Type:type,Kind:involvedObject.kind,FirstSeen:firstTimestamp,LastSeen:lastTimestamp,Component:source.component --sort-by='lastTimestamp' ${params}
}

k-pods() {
  params=($*)
  k get pods -o custom-columns=Name:metadata.name,Host:spec.nodeName,Status:status.phase $params
}

k-pods-g() {
  k-pods |grep "$1"
}

w-k-events() {
  params=($*)
  cmd="kubectl get ev -o=custom-columns=Name:metadata.name,Reason:reason,Type:type,Kind:involvedObject.kind,FirstSeen:firstTimestamp,LastSeen:lastTimestamp,Component:source.component --sort-by='lastTimestamp' ${params}"
  watch $cmd
}

[AlanGreene]

Oracle

TODO: fix path, oci setup autocomplete didn't prompt for path, not sure why it chose ~/lib…

[[ -e "/Users/alan/lib/oci_autocomplete.sh" ]] && source "/Users/alan/lib/oci_autocomplete.sh"

# default is ~/.oci/config
export OCI_CLI_CONFIG_FILE=/Users/alan/.config/oci/config

[AlanGreene]

#!/bin/bash

alias k="kubectl"
if ! command -v kubie &>/dev/null; then
    echo "Install kubie for kubectl context and kubectl namespace operations"
fi

if ! command -v kubectl &> /dev/null; then
    echo "Install kubectl first"
fi

# Just printing what is available
field_selector_list() {
    cat <<EOF
### CertificateSigningRequest ###
spec.signerName

### CronJob###
status.successful

### Event ###
involvedObject.kind
involvedObject.namespace
involvedObject.name
involvedObject.uid
involvedObject.apiVersion
involvedObject.resourceVersion
involvedObject.fieldPath
reason
source (appears to resolve to metadata.source.component, falls back to reportingComponent)
type
reportingComponent

### Job	###
status.successful

### JobTemplate ###
status.successful

### Namespace ###
status.phase

### Node ###
spec.unschedulable

### Pod ###
spec.nodeName
spec.restartPolicy
spec.schedulerName
spec.serviceAccountName
status.phase
status.podIP
status.nominatedNodeName

### ReplicationController
status.replicas

### Secret ###
status.phase
type

### StatefulSet	###
status.successful
EOF
}

kctx() { k config current-context; }
kgv() {  k lineage $1 --output=split --show-group; }
klsctx() { k config get-contexts; }
ksetctx() { k config use-context $1; }
ctx() {
    if [ "$1" == "-f" ]; then
        echo "$1 and $2"
        kubie ctx --kubeconfig "$2"
    elif [ ! -z "$1" ]; then
        kubie ctx $1
    else
	kubie ctx
    fi
}
ns() {
    if [ ! -z "$1" ]; then
        kubie ns $1
    else
	kubie ns
    fi
}
kns() { k config view --minify -o jsonpath='{..namespace}';echo; }
kgew() {
    if [ "$1" == "-A" ]; then
        k get events -A -w --field-selector=type=Warning --sort-by='.metadata.creationTimestamp'
    else
        k get events -w --field-selector=type=Warning --sort-by='.metadata.creationTimestamp'
    fi
}
kgee() {
    if [ "$1" == "-A" ]; then
        k get events -A -w --field-selector=type=Error --sort-by='.metadata.creationTimestamp'
    else
        k get events -w --field-selector=type=Error --sort-by='.metadata.creationTimestamp'
    fi
}
kgewf() {
    if [ "$1" == "-h" ]; then
        field_selector_list
    return 0
    fi
    if [ "$2" == "-A" ]; then
        k get events -w -A --field-selector=$1 --sort-by='.metadata.creationTimestamp'
    else
        k get events -w --field-selector=$1 --sort-by='.metadata.creationTimestamp'
    fi
}
cani() { k auth can-i --list; }
succeeded() {  k get pod -o=jsonpath='{.items[?(@.status.phase=="Succeeded")].metadata.name}'; }
rusage(){
    local GREP=rg # use ripgrep
    local FILTER;

    if [ "$#" -lt 1 ]; then echo "Provide label selector"; fi
    if [ -z "$2" ]; then
        FILTER=$(echo $1 | cut -d'=' -f2)
    else
        FILTER=$2
    fi
    # k resource_capacity -c -l=app=hodor-auth -u | (read line; echo "$line"; rg hodor)
    k resource_capacity -c -l=$1 -u | (read line; echo "$line"; $GREP $FILTER)
}
kallresources() {
	k api-resources --verbs=list -o name --namespaced | xargs -n 1 kubectl get --show-kind --ignore-not-found
}

unused_secrets() {
    envSecrets=$(kubectl get pods -o jsonpath='{.items[*].spec.containers[*].env[*].valueFrom.secretKeyRef.name}' | xargs -n1)
    envSecrets2=$(kubectl get pods -o jsonpath='{.items[*].spec.containers[*].envFrom[*].secretRef.name}' | xargs -n1)
    volumeSecrets=$(kubectl get pods -o jsonpath='{.items[*].spec.volumes[*].secret.secretName}' | xargs -n1)
    pullSecrets=$(kubectl get pods -o jsonpath='{.items[*].spec.imagePullSecrets[*].name}' | xargs -n1)
    tlsSecrets=$(kubectl get ingress -o jsonpath='{.items[*].spec.tls[*].secretName}' | xargs -n1)


    diff \
    <(echo "$envSecrets\n$envSecrets2\n$volumeSecrets\n$pullSecrets\n$tlsSecrets" | sort | uniq) \
    <(kubectl get secrets -o jsonpath='{.items[*].metadata.name}' | xargs -n1 | sort | uniq)
}

kgs() {
    if [ -z "$2" ]; then
        k get secret "$1" -o go-template='{{range $k,$v := .data}}{{printf "%s: " $k}}{{if not $v}}{{$v}}{{else}}{{$v | base64decode}}{{end}}{{"\n"}}{{end}}'
    else
        k get secret -n $2 "$1" -o go-template='{{range $k,$v := .data}}{{printf "%s: " $k}}{{if not $v}}{{$v}}{{else}}{{$v | base64decode}}{{end}}{{"\n"}}{{end}}'
    fi
}