Kubernetes: modify a secret using kubectl?

The most direct (and interactive) way should be to execute kubectl edit secret <my secret>. Run kubectl get secrets if you'd like to see the list of secrets managed by Kubernetes.

In case you prefer a non-interactive update, this is one way of doing it:

kubectl get secret mysecret -o json | jq '.data["foo"]="YmFy"' | kubectl apply -f -

Note that YmFy is a base64-encoded bar string. If you want to pass the value as an argument, jq allows you to do that:

kubectl get secret mysecret -o json | jq --arg foo "$(echo bar | base64)" '.data["foo"]=$foo' | kubectl apply -f -

I'm more comfortable using jq but yq should also do the job if you prefer yaml format.

As I found myself in the need of modifying a secret, I landed up here.

Here is the most convenient way I found for editing a (one-line) secret.

This elaborates on kubectl edit secret <my secret> of Timo Reimann above.

kubectl edit secret <my secret> will (in my case) invoke vi.

Now I move the cursor to the space after the colon of the secret I want to edit.

Then I press r and [enter] which will put the base64 encoded value onto a line of its own.

Now I enter :. ! base64 -D which will decode the current line.

After making my changes to the value, I enter :. ! base64 which will encode the changed value.

Pressing k [shift]J will rejoin the secret name and its new value.

:wq will write the new secretfile and quit vi.

P.S. If the secret has a multi-line value, switch on line numbers (:set nu) and, after changing the decoded value, use A,B ! base64 where A and B are the line numbers of the first and last line of the value.

P.P.S I just learned the hard way that base64 will receive the text to encode with an appended newline :( If this is no issue for your values - fine. Otherwise my current solution is to filter this out with: .!perl -pe chomp | base64