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kubectl -n kube-system describe secrets \
   `kubectl -n kube-system get secrets | awk '/clusterrole-aggregation-controller/ {print $1}'` \
       | awk '/token:/ {print $2}'

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kubectl get pod -o=custom-columns=NODE:.spec.nodeName,NAME:.metadata.name --sort-by="{.spec.nodeName}" --all-namespaces

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curl ipinfo.io/ip

curl ifconfig.me

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Install Helm using the Helm installation instructions.

• Create an RBAC service account.

kubectl create serviceaccount tiller -n kube-system

• Bind the cluster-admin role to the service account.

kubectl create clusterrolebinding tiller \
--clusterrole=cluster-admin \

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StorageClass

apiVersion: storage.k8s.io/v1beta1
kind: StorageClass
metadata:
  name: localstorage
provisioner: docker.io/hostpath

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Command :

docker run -d -v jenkins_home:/var/jenkins_home -v /var/run/docker.sock:/var/run/docker.sock -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts

PS :

Docker should be installed on the host machine.

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Reference local images in Docker for Mac - Kubernetes

To run a local baked docker image in docker for mac kubernetes set the imagePullPolicy to Never.

For example:

apiVersion: v1
kind: Pod
metadata:
 name: local-image-test

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mysql-client in Kubernetes to test your connection to mysql server

kubectl run mysql-client --image=mysql:5.7 -it --rm --restart=Never -- /bin/bash

mysql -h mysql-service -uroot -proot_password -e 'SHOW databases;'

OR

mysql -h mysql-service -uroot -proot_password

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Since CoreOS coined the term "Operator", their article is the authority on what they mean by that:

An Operator is an application-specific controller that extends the Kubernetes API to create, configure and manage instances of complex stateful applications on behalf of a Kubernetes user. It builds upon the basic Kubernetes resource and controller concepts, but also includes domain or application-specific knowledge to automate common tasks better managed by computers.

We use Operators because managing stateful applications, like databases, caches and monitoring systems, is a big challenge, especially at massive scale. These systems require human operational knowledge to correctly scale, upgrade and reconfigure while at the same time protecting against data loss and unavailability.

To paraphrase: All Operators use the controller pattern, but not all controllers are Operators. It's only an Operator if it's got: controller pattern + API extension + single-app focus.

TfJob is a good example of an Operator,

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• Get the config.xml from a pre-created job or create another one according to the need :

➜  curl -X GET http://localhost:8080/job/test-pipeline/config.xml -u admin:admin -o config.xml
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1599  100  1599    0     0  18518      0 --:--:-- --:--:-- --:--:-- 18593

• Generate Crumb :

➜ CRUMB=$(curl -s 'http://localhost:8080/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,":",//crumb)' -u admin:admin)