EnvVar is creating user variables in > 1.0.2

[testworksau]

We are seeing an issue whereby using EnvVar (to read from the environment variable on our build agent) to populate UserVar results in the generated packer template containing only user variables.

packerlicious version

1.1.0 -> 1.3.1

Expected behavior

...
    aws_access_key = EnvVar("AWS_ACCESS_KEY_ID")
    aws_secret_access_key = EnvVar("AWS_SECRET_ACCESS_KEY")

    template = Template()
    var_aws_access_key = UserVar("AWS_ACCESS_KEY_ID", Ref(aws_access_key))
    var_aws_secret_key = UserVar("AWS_SECRET_ACCESS_KEY", Ref(aws_secret_key))
    user_variables = [
        var_aws_access_key,
        var_aws_secret_key
    ]
    
    template.add_variable(user_variables)
    amazon_ebs_builder = builder.AmazonEbs(
        access_key=Ref(var_aws_access_key),
        secret_key=Ref(var_aws_secret_key),
...

This should (or at least used to) yield environment variables in the .json:

...
  "builders": [
    {
      "access_key": "{{user `AWS_ACCESS_KEY_ID`}}",
      "secret_key": "{{user `AWS_SECRET_ACCESS_KEY`}}",
...

  "variables": {
    "AWS_ACCESS_KEY_ID": "{{env `AWS_ACCESS_KEY_ID`}}",
    "AWS_SECRET_ACCESS_KEY": "{{env `AWS_SECRET_ACCESS_KEY`}}"
  }

Actual behavior

User variables end up in the .json file:

  "builders": [
    {
      "access_key": "{{user `AWS_ACCESS_KEY_ID`}}",
      "secret_key": "{{user `AWS_SECRET_ACCESS_KEY`}}",
...

  "variables": {
    "AWS_ACCESS_KEY_ID": "{{user `aws_access_key_id`}}",
    "AWS_SECRET_ACCESS_KEY": "{{user `aws_secret_access_key`}}"
  }

Steps to reproduce

See expected / actual.

[mayn]

hi @testworksau ,
please try removing the Ref() in the UserVar definition.
i.e UserVar("AWS_ACCESS_KEY_ID", aws_access_key)

from packerlicious import builder
aws_access_key = EnvVar("AWS_ACCESS_KEY_ID")
aws_secret_access_key = EnvVar("AWS_SECRET_ACCESS_KEY")
template = Template()
var_aws_access_key = UserVar("AWS_ACCESS_KEY_ID", aws_access_key)
var_aws_secret_key = UserVar("AWS_SECRET_ACCESS_KEY", aws_secret_access_key)
user_variables = [
    var_aws_access_key,
    var_aws_secret_key
]
template.add_variable(user_variables)
amazon_ebs_builder = builder.AmazonEbs(
    ami_name="my_ami",
    source_ami="source_ami",
    instance_type="t2.micro",
    region="us-east-1",
    access_key=Ref(var_aws_access_key),
    secret_key=Ref(var_aws_secret_key),
)
template.add_builder(amazon_ebs_builder)
print(template.to_json())

I believe this give you the output you are looking for.

{
  "builders": [
    {
      "access_key": "{{user `AWS_ACCESS_KEY_ID`}}",
      "ami_name": "my_ami",
      "instance_type": "t2.micro",
      "region": "us-east-1",
      "secret_key": "{{user `AWS_SECRET_ACCESS_KEY`}}",
      "source_ami": "source_ami",
      "type": "amazon-ebs"
    }
  ],
  "variables": {
    "AWS_ACCESS_KEY_ID": "{{env `AWS_ACCESS_KEY_ID`}}",
    "AWS_SECRET_ACCESS_KEY": "{{env `AWS_SECRET_ACCESS_KEY`}}"
  }
}

The behavior changed starting v1.1.0 via 54f7a97
I had the ticket [GH-153] marked as not backwards compatible, but seem i missed adding it to the changelog.

EnvVar were previously rending incorrectly, which is why you also had to specify UserVar().
With the above change, you can simplify your template by removing the use of UserVar:

from packerlicious import builder
aws_access_key = EnvVar("AWS_ACCESS_KEY_ID")
aws_secret_access_key = EnvVar("AWS_SECRET_ACCESS_KEY")
template = Template()
user_variables = [
    aws_access_key,
    aws_secret_access_key
]
template.add_variable(user_variables)
amazon_ebs_builder = builder.AmazonEbs(
    ami_name="my_ami",
    source_ami="source_ami",
    instance_type="t2.micro",
    region="us-east-1",
    access_key=Ref(aws_access_key),
    secret_key=Ref(aws_secret_access_key),
)
template.add_builder(amazon_ebs_builder)
print(template.to_json())

output:

{
  "builders": [
    {
      "access_key": "{{user `aws_access_key_id`}}",
      "ami_name": "my_ami",
      "instance_type": "t2.micro",
      "region": "us-east-1",
      "secret_key": "{{user `aws_secret_access_key`}}",
      "source_ami": "source_ami",
      "type": "amazon-ebs"
    }
  ],
  "variables": {
    "aws_access_key_id": "{{env `AWS_ACCESS_KEY_ID`}}",
    "aws_secret_access_key": "{{env `AWS_SECRET_ACCESS_KEY`}}"
  }
}

Let me know if this helps.

[testworksau]

I did notice a breaking change label on that particular issue, and went looking for mention of it in the docs.

In any case, I'm happy to report that the suggested change works 👍

[mayn]

@testworksau , glad i was able to help.
Question would it help if I expanded out docs like I’ve done for
https://github.com/mayn/packer.py ?

[testworksau]

Docs are always useful, but in my particular case, I'm not sure they would have helped. I didn't write the original python script for the packer build I was looking at; I was troubleshooting why a build that someone else in our company set up - which was working mid last year - had stopped working.

Of course, there was no commentary in the code as to why UserVar was being used in the first place 😄

[mayn]

thanks for the feedback @testworksau . i retroactively updated the changelog to mention this change.