How to put an Argo webhook trigger parameter into an artifact? - kubernetes

Question

I want to be able to POST a big piece of data to a webhook in Argo. In my Sensor definition I get the data from the request and put it into a "raw" artifact on the Workflow. Since the data is base64 encoded, I use a Sprig template to decode the encoded data.
Unfortunately when I use a large amount of data Kubernetes refuses to process the generated Workflow-definition.
Example with raw data
This example works for small amounts of data.
apiVersion: argoproj.io/v1alpha1
kind: Sensor
metadata:
name: webhook
spec:
template:
serviceAccountName: argo-events-sa
dependencies:
- name: input-dep
eventSourceName: webhook-datapost
eventName: datapost
triggers:
- template:
name: webhook-datapost-trigger
k8s:
group: argoproj.io
version: v1alpha1
resource: workflows
operation: create
source:
resource:
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
generateName: webhook-datapost-
spec:
entrypoint: basefile
imagePullSecrets:
- name: regcred
arguments:
artifacts:
- name: filecontents
raw:
data: ""
templates:
- name: basefile
serviceAccountName: argo-events-sa
inputs:
artifacts:
- name: filecontents
path: /input.file
container:
image: alpine:latest
command: ["ls"]
args: ["/input.file"]
parameters:
- src:
dependencyName: input-dep
dataTemplate: "{{ .Input.body.basedata | b64dec }}"
dest: spec.arguments.artifacts.0.raw.data
Error with larger dataset
When I trigger the example above with a small dataset, this works as expected. But when I use a large dataset, I get an error:
Pod "webhook-datapost-7rwsm" is invalid: metadata.annotations: Too long: must have at most 262144 bytes
I understand that this is due to copying the entire raw data into the Workflow-template. This large template is then rejected by Kubernetes.
I am looking for a method to copy the data from a webhook POST-request into an artifact, without the entire payload being copied into the Workflow-template. Is there a possibility with Argo?