resource/aws_lambda_alias: Support Traffic Shifting

[eggsbenjamin]

Added routing_configproperty to aws_lambda_alias which contains additional_version_weights to afford lambda alias traffic shifting.

Acceptance tests:

=== RUN   TestAccAWSLambdaAlias_basic
--- PASS: TestAccAWSLambdaAlias_basic (37.61s)
=== RUN   TestAccAWSLambdaAlias_routingConfig
--- PASS: TestAccAWSLambdaAlias_routingConfig (69.14s)
PASS
ok      github.com/terraform-providers/terraform-provider-aws/aws       106.787s

[eggsbenjamin]

Hey @radeksimko, I hope I don't sound impatient but, is there any chance I could get some feedback on this submission please? Cheers.

[alikor]

When will this feature be released?

[kylegalbraith]

Any idea when this feature will be rolled out? We would like to use it for some blue/green deployments.

[bflad]

Hi @eggsbenjamin 👋 Thanks for submitting this!

I left you some initial feedback below which will require some code changes to properly handle drift detection. Please let us know if you have any questions or do not have time to implement these changes. Thanks!

[bflad]

While this still works today, Elem should only contain *schema.Schema or *schema.Resource 👍 In this case, it can be fixed with:

Elem: &schema.Schema{Type: schema.TypeFloat},

[bflad]

Including the optional and empty AliasRoutingConfiguration{} here seems extraneous during the create function -- more generally though, we prefer to move the logic to populate a parameter like this into an "expandServiceThing()" type method, which can be reused in create and update functions. e.g.

func expandLambdaAliasRoutingConfiguration(l []interface{}) *lambda.AliasRoutingConfiguration {
  aliasRoutingConfiguration := &lambda.AliasRoutingConfiguration{}

  if len(l) == 0 || l[0] == nil {
    return aliasRoutingConfiguration
  }

  m := l[0].(map[string]interface{})

  if v, ok := m["additional_version_weights"]; ok {
    aliasRoutingConfiguration.AdditionalVersionWeights = expandFloat64Map(weights)
  }

  return aliasRoutingConfiguration
}

// this should live in structure.go near expandStringList and replace readAdditionalVersionWeights
func expandFloat64Map(m map[string]interface{}) map[string]*float64 {
	float64Map := make(map[string]*float64, len(m))
	for k, v := range m {
		float64Map[k] = aws.Float64(v.(float64))
	}
	return float64Map
}

and called in create/update via: RoutingConfig: expandLambdaAliasRoutingConfiguration(d.Get("routing_config").([]interface{}))

[bflad]

When using d.Set() with aggregate types (TypeList, TypeSet, TypeMap), we should perform error checking to prevent issues where the code is not properly able to set the Terraform state. e.g.

if err := d.Set("routing_config", aliasConfiguration.RoutingConfig); err != nil {
  return fmt.Errorf("error setting routing_config: %s", err)
}

Without this check and if there is a type conversion error, Terraform is silently accepting the configuration "as-is" into the Terraform state and unable to detect drift from the API should changes occur outside Terraform.

After adding this error checking, you should start receiving type errors as aliasConfiguration.RoutingConfig is a SDK object and not a []interface{}. We generally handle this via a "flattenServiceObject()" function. e.g.

func flattenLambdaAliasRoutingConfiguration(arc *lambda.AliasRoutingConfiguration) []interface{} {
	if arc == nil {
		return []interface{}{}
	}

	m := map[string]interface{}{
		"additional_version_weights": aws.Float64ValueMap(arc.AdditionalVersionWeights)
	}

	return []interface{}{m}
}

Which can be referenced via:

if err := d.Set("routing_config", flattenLambdaAliasRoutingConfiguration(aliasConfiguration.RoutingConfig)); err != nil {
  return fmt.Errorf("error setting routing_config: %s", err)
}

[bflad]

It looks like this documentation reference was added but never referenced above.

[eggsbenjamin]

Hi @bflad , thanks for the response. Cool, I'll update the PR!

[eggsbenjamin]

@bflad updated with the suggested changes. Cheers.

[bflad]

Great work, @eggsbenjamin! 🚀

make testacc TEST=./aws TESTARGS='-run=TestAccAWSLambdaAlias'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -run=TestAccAWSLambdaAlias -timeout 120m
=== RUN   TestAccAWSLambdaAlias_basic
--- PASS: TestAccAWSLambdaAlias_basic (24.96s)
=== RUN   TestAccAWSLambdaAlias_nameupdate
--- PASS: TestAccAWSLambdaAlias_nameupdate (43.52s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	68.534s

[bflad]

This has been released in version 1.26.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!