Raw templates do not use existing parameters

[aarongorka]

When diffing/building with a raw template, existing parameters/variables do not get used.

Traceback (most recent call last):
  File "/home/aaron.gorka/.local/lib/python2.7/site-packages/stacker/plan.py", line 89, in _run_once
    status = self.fn(self.stack, status=self.status)
  File "/home/aaron.gorka/.local/lib/python2.7/site-packages/stacker/actions/diff.py", line 228, in _diff_stack
    stack.resolve(self.context, provider)
  File "/home/aaron.gorka/.local/lib/python2.7/site-packages/stacker/stack.py", line 187, in resolve
    self.blueprint.resolve_variables(self.variables)
  File "/home/aaron.gorka/.local/lib/python2.7/site-packages/stacker/blueprints/raw.py", line 139, in resolve_variables
    self.name
  File "/home/aaron.gorka/.local/lib/python2.7/site-packages/stacker/blueprints/raw.py", line 63, in resolve_variable
    raise MissingVariable(blueprint_name, var_name)
MissingVariable: Variable "MyParameter" in blueprint "my-app" is missing
[2018-05-07T08:33:30] DEBUG my-app stacker.plan:143(set_status): Setting my-app state to failed.
[2018-05-07T08:33:30] INFO my-app stacker.ui:37(info): my-app: failed (Variable "MyParameter" in blueprint "my-app" is missing)
[2018-05-07T08:33:30] ERROR MainThread stacker.actions.base:188(execute): The following steps failed: my-app

In this case the my-app stack is already deployed with the parameter MyParameter as NoEcho. Ideally, It would be nice if Stacker could understand that the parameter is already set and can be reused with the UsePreviousValue setting when building (http://boto3.readthedocs.io/en/latest/reference/services/cloudformation.html#CloudFormation.Client.create_stack). When running a diff, it can assume that nothing has changed.

Stacker version: 1.3.0
Steps to reproduce: manually deploy a CloudFormation template with 1 parameter (ideally NoEcho as there seems to be some logic in _handle_missing_parameters that pulls the existing values down). Then, run a diff/build with the variable omitted.

[ejholmes]

@aarongorka can you provide a cloudformation template that reproduces the issue?

I have a feeling the source the problem is related to NoEcho and this line:
https://github.com/remind101/stacker/blob/dad8cd8625a984bf71ee0fcab7df91d5b29ace0f/stacker/actions/build.py#L136-L137

That should probably be using UsePreviousValue instead of ParameterValue: https://docs.aws.amazon.com/AWSCloudFormation/latest/APIReference/API_Parameter.html

[aarongorka]

template.yml:

AWSTemplateFormatVersion: "2010-09-09"

Parameters:
  MyNormalParam:
    Type: String
  MyPrivateParam:
    Type: String
    NoEcho: true

Resources:
  Bucket:
    Type: 'AWS::S3::Bucket'
    Properties:
        BucketName: !Sub "${AWS::AccountId}-${MyNormalParam}-${MyPrivateParam}"

stacker.yml:

namespace: ""
namespace_delimiter: ""
stacks:
  - name: param-test-stack
    template_path: ./template.yml
    variables:
      MyNormalParam: stacker
      MyPrivateParam: test-bucket

You can test by deploying as-is, then try to update after commenting out one or more of the variables.

The error occurs with both normal parameters and NoEcho parameters.

Is stacker/stacker/actions/build.py the right place to contain this logic if both build and diff require it? The exception is currently being raised in resolve_variable which happens before the above resolution happens.

[phobologic]

Hey @aarongorka - this should be fixed in #615. Take a look and let me know if you run into any other issues!