Update ECS Service only when TaskDefinition is changed locally in pulumi

I created ECS Service and initial TaskDefintion with pulumi, then I set up automatic deployment (creating new task definition and update service from CI).

In this configuration, how do I achieve both of 1 and 2?:

1. When pulumi up without change, expects no change.
2. When pulumi up with change on task definition, expects updating Service.

pulumi/pulumi-awsx#856 suggests ignoreChanges but it does not solve the second case. Maybe we need to have ignoreChanges with function, to ignore only when updating revision is older than the state.

Current behavior of pulumi up after task def & service are updated by automatic deployment:

When I made NO changes to task def and without ignoreChanges

        ~ aws:ecs/service:Service: (update)
            [id=...]
            [urn=...]
            [provider=...]
          ~ taskDefinition: "arn:aws:ecs:ap-northeast-1:XXXXXXXXXXXX:task-definition/our-app-rails:5" => "arn:aws:ecs:ap-northeast-1:711533999350:task-definition/our-app-rails:4"

Pulumi is reverting task definition revision of service, even after pulumi refresh (Use Case of pulumi/pulumi-awsx#856)

When I made SOME changes to task def and with ignoreChanges (in transformations

     └─ awsx:x:ecs:FargateTaskDefinition  rails
 +-     └─ aws:ecs:TaskDefinition         rails           replace     [diff: ~containerDefinitions]

and no Service update.

[lukehoban]

This means that the environment variable with an undefined value got ignored (makes sense) but now the provider calculates the difference as if it was meaningful.

This is due to the design of the upstream provider diff implementation - which does some normalization on containerDefinitions, but does not normalize empty values. You must either leave off env vars that are undefined, or specify them with the empty string value. The request to handle this and similar issues more specifically in the upstream provider is https://github.com/hashicorp/terraform-provider-aws/issues/11526.

[mikhailshilkov]

When I run the repro from @phillipedwards for the second time, this is the essence of the diff that I get:

                  ~ environment : [
                      + [1]: {
                              + name: "boolean-test"
                            }
                    ]

This means that the environment variable with an undefined value got ignored (makes sense) but now the provider calculates the difference as if it was meaningful.

I believe this is specific to the provider implementation, so I’ll move the issue to pulumi-aws.