How do I populate the depends_on on an aws_api_gateway_deployment resource if the aws_api_gateway_integration was created in a Terraform module?

Question

In the Terraform docs for aws_api_gateway_deployment it says:

Note: Depends on having aws_api_gateway_integration inside your rest api (which in turn depends on aws_api_gateway_method). To avoid race conditions you might need to add an explicit depends_on = ["aws_api_gateway_integration.name"].

My aws_api_gateway_deployment resource lives in the root module but most of the aws_api_gateway_integrations are created in a child module (this is a local module created by me).

My understanding is that you can't export a resource from a module.

The folder structure is:

 - main.tf <-- contains the aws_api_gateway_rest_api and aws_api_gateway_deployment and uses the service_func_lambda module multiple times
 - modules/
   - service_func_lambda/
     - main.tf <-- contains the aws_api_gateway_integration and other bits such as aws_api_gateway_method and aws_api_gateway_resource

How can I reference the aws_api_gateway_integration that is created inside the module from the calling, root module?

score 2 · Answer 1 · answered Mar 21 '19 at 14:55

2

You cannot depend on a resource inside another module. You can create an implicit dependency on an entire module by referencing an output of that module.

I think you can use null_resource for this (though there may be a better way). Create a null resource like this, then have your aws_api_gateway_deployment depend on it:

resource "null_resource" "depend_on_module" {
  triggers {
    service_func_lambda_module_output = "${module.service_func_for_lambda.some_output}"
  }
}

answered Mar 21 '19 at 14:55

Eric M. Johnson

6,657
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Ok cool. Although it feels like a bit of a hack, I guess this achieves the ultimate goal. Thanks! – Force Hero Mar 21 '19 at 15:35
On further inspection I'm not sure I follow. Do I declare that `null_resource` inside the module or outside? What does the `depends_on` attribute look like in the `aws_api_gateway_deployment` resource? – Force Hero Mar 22 '19 at 07:13

score 2 · Accepted Answer · answered Mar 23 '19 at 15:34

2

So in the end I made the aws_api_gateway_deployment depend on the whole module. This seemed to work nicely:

resource "aws_api_gateway_deployment" "api_gw_deploy" {

  depends_on = [
    "module.user_func_list",
    "module.user_func_create",
    "module.resource_func_list",
  ]

  rest_api_id = "${aws_api_gateway_rest_api.main_api_gw.id}"
  stage_name  = "live"
}

answered Mar 23 '19 at 15:34

Force Hero

2,674
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35

1

You can depend on an entire module? The more you know. – Eric M. Johnson Mar 23 '19 at 16:35

How do I populate the depends_on on an aws_api_gateway_deployment resource if the aws_api_gateway_integration was created in a Terraform module?

2 Answers2