Error when trying to pass Env Vars as a parameter to a template, cannot unmarshal object into Go struct

[RoryDoherty]

Checklist

• Double-checked my configuration.
• Tested using the latest version.
• Used the Emissary executor.

Summary

What happened/what you expected to happen?
Tried to pass a parameter as a json/list of env vars but get the following error when submitting the workflow:

 Unsuccessful HTTP response: json: cannot unmarshal object into Go struct field ScriptTemplate.workflow.spec.templates.script.env of type []v1.EnvVar

I have tried various assortments of quotes, yaml continuation using | and >

According to this thread on slack it did work at some stage so this may be a regression:
https://cloud-native.slack.com/archives/C01QW9QSSSK/p1628785975367900

What version are you running?
v3.3.5

Diagnostics

Paste the smallest workflow that reproduces the bug. We must be able to run the workflow.

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: demo-
  namespace: argoci
spec:
  entrypoint: demo
  templates:
    - name: demo
      dag:
        tasks:
          - name: env-var-test
            template: run-test
            arguments:
              parameters:
                - name: vars
                  value: |
                    [
                      {name: "Foo", value: "bar"},
                      {name: "Bar", value: "foo"},
                      {name: "zoo", value: "animal"}
                    ]

    - name: run-test
      inputs:
        parameters:
          - name: vars
      script:
        image: ubuntu:18.04
        imagePullPolicy: Always
        command: [bash]
        workingDir: "/src"
        env: {{inputs.parameters.vars}}
        source: |
          env

Logs from the workflow controller:

There were no logs in the workflow controller when I submitted the workflow via the UI
Is there a trace logs setting I can enable?

---

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[sandeepk8s]

@RoryDoherty Try this

script:
   image: ubuntu:18.04
   command:
     - bash
   workingDir: /src
   env:
     - name: a
       value: '{{inputs.parameters.vars}}'
   source: |
     echo $a

[RoryDoherty]

@sandeepitachi
Thanks, I tried that and yes that works, I get this output:

[ {name: "Foo", value: "bar"}, {name: "Bar", value: "foo"}, {name: "zoo", value: "animal"} ]

However I'm not trying to pass that as a string, I want to be able to set the env vars for a template within the dag task.
So in my original example I want "Foo" "Bar" and "zoo" to be environment variables I can access within the script section

[RoryDoherty]

I can work around this for now using the following:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: demo-
spec:
  entrypoint: demo
  templates:
    - name: demo
      dag:
        tasks:
          - name: env-var-test
            template: run-test
            arguments:
              parameters:
                - name: vars
                  value: |
                    export Foo="bar"
                    export Bar="Foo"

    - name: run-test
      inputs:
        parameters:
          - name: vars
      script:
        image: ubuntu:18.04
        imagePullPolicy: Always
        command: [bash]
        workingDir: "/src"
        env: 
          - name: vars
            value: '{{inputs.parameters.vars}}'
        source: |
          echo $vars > /tmp/vars
          source /tmp/vars
          env

But it would definitely be good if we could set environment variables from the task and not just in the template

[sarabala1979]

@RoryDoherty This is by design this is not a bug. Script Template is using v1.container spec. if v1.container will accept the array of EnvVar.
We can enhance the controller to parse the JSON and convert []envVar.

[RoryDoherty]

Thanks @sarabala1979 , I had seen a similar snippet in a slack thread as a working example in an earlier release which is why I opened it as a bug!
I'm happy for it to be converted to an enhancement though, if you want to point me in the right direction of where the processing is I'd be happy to take a crack at it

[alexec]

I don’t believe it is possible to change this behavior The templating merging works by marshaling the string into a struct. It cannot cater for arbitrary string due to whitespacing. Even if you managed to get it to work, any small change to white space would break it.

@RoryDoherty suggestion is looks like a good work-around.