Clever Geek Handbook

Kubernetes tips & tricks: handy kubectl templates

Inside the company, we actively share the knowledge we have gained with each other: not only in the form of formal wiki instructions, but also messages in Slack (and so that nothing gets lost, a smart search system is provided, but that's another story ...). We have already accumulated a large number of various templates for console operations in Kubernetes with kubectl. They will be discussed in this article.







Some teams may turn out to be a daily routine for some readers, but if there are those who will discover new things for themselves, thereby improving their effectiveness, the goal of the article will be achieved.



NB : Some of the commands listed below were compiled by our engineers, while others were found on the Internet. In the latter case, they have been tested and found to be useful.



So let's go!



pod'



  1. , pod' --all-namespaces . , — -A ( , Kubernetes 1.15).
  2. pod', (.. Running)? 



    kubectl get pods -A --field-selector=status.phase!=Running | grep -v Complete






    , --field-selector (. ).
  3. : 



    kubectl get no -o json | \
  jq -r '.items | sort_by(.status.capacity.memory)[]|[.metadata.name,.status.capacity.memory]| @tsv'


  4. pod' : 



    kubectl get po -o json --all-namespaces | \
  jq '.items | group_by(.spec.nodeName) | map({"nodeName": .[0].spec.nodeName, "count": length}) | sort_by(.count)'


  5. , - DaemonSet - . — , - , DaemonSet': 



    ns=my-namespace
pod_template=my-pod
kubectl get node | grep -v \"$(kubectl -n ${ns} get pod --all-namespaces -o wide | fgrep ${pod_template} | awk '{print $8}' | xargs -n 1 echo -n "\|" | sed 's/[[:space:]]*//g')\"
  6. kubectl top pod', : 



    # cpu
kubectl top pods -A | sort --reverse --key 3 --numeric
# memory
kubectl top pods -A | sort --reverse --key 4 --numeric
  7. pod' — , : 



    kubectl get pods --sort-by=.status.containerStatuses[0].restartCount






    , (. PodStatus ContainerStatus).




  1. Ingress', pod' . , -o wide: 



    kubectl -n jaeger get svc -o wide
NAME                            TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)                                  AGE   SELECTOR

jaeger-cassandra                ClusterIP   None              <none>        9042/TCP                                 77d   app=cassandracluster,cassandracluster=jaeger-cassandra,cluster=jaeger-cassandra


    , , pod'.
  2. pod' limits requests: 



    kubectl get pods -n my-namespace -o=custom-columns='NAME:spec.containers[*].name,MEMREQ:spec.containers[*].resources.requests.memory,MEMLIM:spec.containers[*].resources.limits.memory,CPUREQ:spec.containers[*].resources.requests.cpu,CPULIM:spec.containers[*].resources.limits.cpu'


  3. kubectl run ( create, apply, patch) — --dry-run. -o yaml, . : 



    kubectl run test --image=grafana/grafana --dry-run -o yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    run: test
  name: test
spec:
  replicas: 1
  selector:
    matchLabels:
      run: test
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: test
    spec:
      containers:
      - image: grafana/grafana
        name: test
        resources: {}
status: {}


    , / .
  4. - : 



    kubectl explain hpa

KIND:     HorizontalPodAutoscaler
VERSION:  autoscaling/v1

DESCRIPTION:
     configuration of a horizontal pod autoscaler.

FIELDS:
   apiVersion    <string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#resources

   kind    <string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds

   metadata    <Object>
     Standard object metadata. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata

   spec    <Object>
     behaviour of autoscaler. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status.

   status    <Object>
     current information about the autoscaler.


    !




  1. IP- : 



    kubectl get nodes -o json | \
  jq -r '.items[].status.addresses[]? | select (.type == "InternalIP") | .address' | \
  paste -sd "\n" -


  2. nodePort, : 



    kubectl get --all-namespaces svc -o json | \
  jq -r '.items[] | [.metadata.name,([.spec.ports[].nodePort | tostring ] | join("|"))]| @tsv'


  3. , CNI (, Flannel), pod' . pod', : 



    kubectl get nodes -o jsonpath='{.items[*].spec.podCIDR}' | tr " " "\n"






  1. pod' c timestamp : 



    kubectl -n my-namespace logs -f my-pod --timestamps

2020-07-08T14:01:59.581788788Z fail: Microsoft.EntityFrameworkCore.Query[10100]


    , ?
  2. , pod' — --tail: 



    kubectl -n my-namespace logs -f my-pod --tail=50
  3. pod': 



    kubectl -n my-namespace logs -f my-pod --all-containers
  4. pod' label': 



    kubectl -n my-namespace logs -f -l app=nginx
  5. , , , : 



    kubectl -n my-namespace logs my-pod --previous




  1. ? 



    kubectl get secrets -o json --namespace namespace-old | \
  jq '.items[].metadata.namespace = "namespace-new"' | \
  kubectl create-f  -
  2. : 



    openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=grafana.mysite.ru/O=MyOrganization"
kubectl -n myapp create secret tls selfsecret --key tls.key --cert tls.crt




Instead of a conclusion - a small list of similar materials and collections found on the Internet:





PS



Read also on our blog:





More articles:


All Articles