Terraform Module depends_on, Part Deux

confluent-main.tf

# This file should be at /confluent/main.tf

variable "kafka_cluster_deployment_done" {}

module "confluent_tools" {
    source = "../server-group/"

    rolling_deployment_done = "${var.kafka_cluster_deployment_done}"
}

kafka-main.tf

# This file should be at /kafka/main.tf

module "kafka_brokers" {
    source = "../server-group/"
}

output "rolling_deployment_done" {
    value = "${module.kafka_brokers.rolling_deployment_done}"
}

main.tf

# This is our top-level example

module "kafka" {
    source = "./kafka"
}

module "confluent" {
    source = "./confluent"

    kafka_cluster_deployment_done = "${module.kafka.rolling_deployment_done}"
}

server-group-main.tf

# This file should be at /server-group/main.tf

variable "rolling_deployment_done" {
  default = "foo"
}

resource "null_resource" "rolling_deployment" {
  triggers {
    bar = "${var.rolling_deployment_done}"
  }

  provisioner "local-exec" {
    command = "echo 'server-group.rolling_deployment sleeping for 3 seconds' && sleep 3"
  }
}

output "rolling_deployment_done" {
  value = "${null_resource.rolling_deployment.triggers.bar}"
}

Running terraform apply on this produces the desired behavior of the Kafka module finishing its execution before the Confluent module begins!