Extracting resource in Argo workflow using "resource" template/step with "get" action and passing to downstream steps? - kubernetes

Question

I'm exploring an easy way to read K8S resources in the Argo workflow. The current documentation is focusing mainly on create/patch with conditions (https://argoproj.github.io/argo/examples/#kubernetes-resources), while I'm curious if it's possible to perform "action: get", extra part of the resource state (or full resource) and pass it downstream as artifact or result output. Any ideas?

Answer 1

action: get is not a feature available from Argo.
However, it's easy to use kubectl from within a Pod and then send the JSON output to an output parameter. This uses a BASH script to send the JSON to the result output parameter, but an explicit output parameter or an output artifact are also viable options.
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
generateName: kubectl-bash-
spec:
entrypoint: kubectl-example
templates:
- name: kubectl-example
steps:
- - name: generate
template: get-workflows
- - name: print
template: print-message
arguments:
parameters:
- name: message
value: "{{steps.generate.outputs.result}}"
- name: get-workflows
script:
image: bitnami/kubectl:latest
command: [bash]
source: |
some_workflow=$(kubectl get workflows -n argo | sed -n 2p | awk '{print $1;}')
kubectl get workflow "$some_workflow" -ojson
- name: print-message
inputs:
parameters:
- name: message
container:
image: alpine:latest
command: [sh, -c]
args: ["echo result was: '{{inputs.parameters.message}}'"]
Keep in mind that kubectl will run with the permissions of the Workflow's ServiceAccount. Be sure to submit the Workflow using a ServiceAccount which has access to the resource you want to get.