How to use kubectl patch to add list entry without duplicate? - kubectl

Question

I have the following Minikube default service account:
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
imagePullSecrets:
- name: gcr-secret
- name: awsecr-cred
- name: dpr-secret
- name: acr-secret
kind: ServiceAccount
metadata:
creationTimestamp: "2022-11-18T20:21:13Z"
name: default
namespace: default
resourceVersion: "10953591"
uid: edcc687f-dbb5-472d-8847-b4dc29096b48
I can add a new imagePullSecrets entry using the following kubectl patch command:
kubectl patch serviceaccount default --type=json -p '[{"op": "add", "path": "/imagePullSecrets/-", "value": {name: artifactory-credentials}}]'
Here's the update default service account:
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
imagePullSecrets:
- name: gcr-secret
- name: awsecr-cred
- name: dpr-secret
- name: acr-secret
- name: artifactory-credentials
kind: ServiceAccount
metadata:
creationTimestamp: "2022-11-18T20:21:13Z"
name: default
namespace: default
resourceVersion: "10956724"
uid: edcc687f-dbb5-472d-8847-b4dc29096b48
However, when I run the kubectl patch command a second time, a duplicate imagePullSecrets entry is added:
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
imagePullSecrets:
- name: gcr-secret
- name: awsecr-cred
- name: dpr-secret
- name: acr-secret
- name: artifactory-credentials
- name: artifactory-credentials
kind: ServiceAccount
metadata:
creationTimestamp: "2022-11-18T20:21:13Z"
name: default
namespace: default
resourceVersion: "10957065"
uid: edcc687f-dbb5-472d-8847-b4dc29096b48
How can I use kubectl patch to add a imagePullSecrets entry only when the entry doesn't already exist? I don't want duplicate imagePullSecrets entries.
I'm using Minikube v1.28.0 and kubectl client version v1.26.1 / server version v1.25.3 on Ubuntu 20.04.5 LTS.

Answer 1

AFAIK unfortunately there is no such filter available the official documentation. But We can do a workaround by using the general syntax like kubectl patch serviceaccount default --type=json -p '{"imagePullSecrets":[{"name": "gcr-secret"},{"name": "artifactory-credentials"},{"name": "acr-secret"}]}'. But we have to update all the imagePullSecrets everytime.
As #Geoff Alexander mentioned the other way is to get the details of resource and validate if the required property is available in the resource, as mentioned in the above comment like $kubectl get serviceaccount -o json or $kubectl get serviceaccount -o yaml.