'Error generating params' error when using JSON array in Git files generator file

[jgwest]

An 'error generating params' error is output when using the following ApplicationSet on the specified repo.

The following ApplicationSet will trigger the error:

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: guestbook
spec:
  generators:
  - git:
      revision: HEAD
      repoURL: https://github.com/jgwest/argocd-example-apps.git
      files:
        - path: appset-examples/git-files-example/config/clusters.json   # <--- this line is the important one
  template:
    metadata:
      name: '{{cluster.name}}-guestbook'
    spec:
      project: default
      source:
        repoURL: https://github.com/jgwest/argocd-example-apps.git
        targetRevision: HEAD
        path: appset-examples/git-files-example/apps/guestbook/{{appVersions.guestbook}}
      destination:
        server: https://kubernetes.default.svc
        namespace: guestbook

This is because the cluster.json (referenced above) looks like this (source):

[
  {
    "account": "123456",
    "asset_id": "11223344",
    // ...
  },
  {
    "account": "456789",
    "asset_id": "55667788",
    // ...
  }
]

Notice that this is a JSON array (of objects), rather than a single JSON object... it appears the current Git file generator parsing code assumes that files will only be JSON objects, not JSON arrays.

Error log:

INFO[0448] Trace                                         args="[git clean -fdx]" dir="/tmp/https:__github.com_jgwest_argocd-example-apps" operation_name="exec git" time_ms=4.000146000000001
ERRO[0448] error generating params                       error="json: cannot unmarshal array into Go value of type map[string]interface {}" generator="&{0xc0003a4f00}"
2021-01-26T12:01:54.853-0500	ERROR	controller-runtime.manager.controller.applicationset	Reconciler error	{"reconciler group": "argoproj.io", "reconciler kind": "ApplicationSet", "name": "guestbook", "namespace": "argocd", "error": "json: cannot unmarshal array into Go value of type map[string]interface {}"}

[OmerKahani]

What should be the behavior with a JSON list? Should it iterate on the list, like the list generator?

[jgwest]

Good question, I was thinking that generateParamsFromGitFile should first attempt to parse the JSON file as a JSON object, and then, if that fails, next try to parse it as a JSON array.

In the case of the JSON object, the code would work as it does now. In the case of the JSON array, it would instead attempt to parse each element in the array, and treat each element as a separate set of parameters (as you said, iterating through the list).

So for this...

[
  {
    "account": "123456",
    "asset_id": "11223344",
    // ...
  },
  {
    "account": "456789",
    "asset_id": "55667788",
    // ...
  }
]

... you would get 2 separate parameter maps, each to be passed separately to the template:

account: 123456
asset_id 11223344

and

account: 456789
asset_id: 55667788