CustomResources do not respect DependsOn

[Sayan-]

This is an issue in v4

CustomResources still follow the pattern in #132. The goformation library has since changed to using field types and custom JSON marshal/unmarshal in #245.

This is problematic when I attempt to create a CustomResource in a Template. The DependsOn will never be populated correctly during a Template.YAML() or Template.JSON() call.

Additionally, there are actually two versions of CustomResources in this library:

in: github.com/awslabs/goformation/v4/cloudformation

goformation/cloudformation/custom_resource.go

Lines 9 to 22 in 785575a

	// See: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cfn-customresource.html
	type CustomResource struct {
	Type string `json:"Type,omitempty"`
	Properties map[string]interface{} `json:"Properties,omitempty"`
	// _deletionPolicy represents a CloudFormation DeletionPolicy
	_deletionPolicy policies.DeletionPolicy
	// _dependsOn stores the logical ID of the resources to be created before this resource
	_dependsOn []string
	// _metadata stores structured data associated with this resource
	_metadata map[string]interface{}
	}

vs

in: github.com/awslabs/goformation/v4/cloudformation/cloudformation

goformation/cloudformation/cloudformation/aws-cloudformation-customresource.go

Lines 11 to 31 in 785575a

	// CustomResource AWS CloudFormation Resource (AWS::CloudFormation::CustomResource)
	// See: http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cfn-customresource.html
	type CustomResource struct {
	// ServiceToken AWS CloudFormation Property
	// Required: true
	// See: http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cfn-customresource.html#cfn-customresource-servicetoken
	ServiceToken string `json:"ServiceToken,omitempty"`
	// AWSCloudFormationDeletionPolicy represents a CloudFormation DeletionPolicy
	AWSCloudFormationDeletionPolicy policies.DeletionPolicy `json:"-"`
	// AWSCloudFormationDependsOn stores the logical ID of the resources to be created before this resource
	AWSCloudFormationDependsOn []string `json:"-"`
	// AWSCloudFormationMetadata stores structured data associated with this resource
	AWSCloudFormationMetadata map[string]interface{} `json:"-"`
	// AWSCloudFormationCondition stores the logical ID of the condition that must be satisfied for this resource to be created
	AWSCloudFormationCondition string `json:"-"`
	}

[douglas-gibbons-lark]

Here's a simple example, showing the issue:

package main

import (
	"io/ioutil"

	"github.com/awslabs/goformation/v4/cloudformation"
)

func main() {
	c := &cloudformation.CustomResource{
		Type: "AWS::Something::Someting",
		Properties: map[string]interface{}{
			"Foo": "Bar",
		},
	}

       // This sets the _dependsOn private field which is never Marshaled into JSON
	c.SetDependsOn([]string{"OtherResource"})

	t := cloudformation.NewTemplate()
	t.Resources["customResource"] = c

	j, _ := t.JSON()
	ioutil.WriteFile("/tmp/stack.json", j, 0644)
}

This outputs:

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Resources": {
    "customResource": {
      "Properties": {
        "Foo": "Bar"
      },
      "Type": "AWS::Something::Somehting"
    }
  }
}

i.e. It's missing DependsOn.

[sgavulla]

I can confirm that DependsOn is missing as mentioned by @douglas-gibbons-lark. This is needed otherwise our stack creation fails (the custom resource for our stack dependsOn a DDB table to be created first).

[xrn]

Let's close it 🎊 @PaulMaddox

[Sayan-]

Amazing! Thank you @xrn - I entirely forgot about this thread.