[SOLVED] How to edit a kubernetes resource from a shell script

Issue

I went through the documentation to edit kubernetes resource using kubectl edit command. Once I execute the command, the file in YAML-format is opened in the editor where I can change the values as per requirement and save it. I am trying to execute these steps by means of sed. How can the following steps be achieved?

1. Execute kubectl edit for a deployment resource
2. Set a value from true to false (using sed)
3. Save the changes

I tried to achieve this in the following way :

$ kubectl edit deployment tiller-deploy -n kube-system | \
   sed -i "s/\(automountServiceAccountToken:.*$\)/automountServiceAccountToken: true/g"`

Solution

Your command is missing a backtick. But even though you put it there, it won't work. The reason is because when you do kubectl edit ..., it edits the file on vim. I am not sure sed would work on vim though. Even though if it does, the output goes to a file, so you get the Vim: Warning: Output is not to a terminal error, which I don't know how to solve.

I would recommend you to get the file and save it. Replace the desired parameters and run it again:

kubectl get deploy tiller-deploy -n kube-system -o yaml > tiller.yaml && sed -i "s/automountServiceAccountToken:.*$/automountServiceAccountToken: true/g" tiller.yaml && kubectl replace -f tiller.yaml

I tried the command above and it worked.

Note: no need to add -n kube-system as the yaml file already contains the namespace.

Answered By - suren