diff --git a/README.md b/README.md
index cc3355f..bffc4b5 100644
--- a/README.md
+++ b/README.md
@@ -121,27 +121,27 @@ By default, this module creates a task definition with a single container defini
 | dockerLabels | A key/value map of labels to add to the container | `map(string)` | `{}` | no |
 | dockerSecurityOptions | A list of strings to provide custom labels for SELinux and AppArmor multi-level security systems | `list(string)` | `[]` | no |
 | entryPoint | The entry point that is passed to the container | `list(string)` | `[]` | no |
-| environment | The environment variables to pass to a container | `list(string)` | `[]` | no |
+| environment | The environment variables to pass to a container | `list(map(string))` | `[]` | no |
 | essential | If the essential parameter of a container is marked as true, and that container fails or stops for any reason, all other containers that are part of the task are stopped | `bool` | `true` | no |
 | execution\_role\_arn | The Amazon Resource Name (ARN) of the task execution role that the Amazon ECS container agent and the Docker daemon can assume | `string` | `""` | no |
 | extraHosts | A list of hostnames and IP address mappings to append to the /etc/hosts file on the container | `list(string)` | `[]` | no |
 | family | You must specify a family for a task definition, which allows you to track multiple versions of the same task definition | `any` | n/a | yes |
-| healthCheck | The health check command and associated configuration parameters for the container | `map(string)` | `{}` | no |
+| healthCheck | The health check command and associated configuration parameters for the container | `any` | `{}` | no |
 | hostname | The hostname to use for your container | `string` | `""` | no |
 | image | The image used to start a container | `string` | `""` | no |
 | interactive | When this parameter is true, this allows you to deploy containerized applications that require stdin or a tty to be allocated | `bool` | `false` | no |
 | ipc\_mode | The IPC resource namespace to use for the containers in the task | `string` | `"host"` | no |
 | links | The link parameter allows containers to communicate with each other without the need for port mappings | `list(string)` | `[]` | no |
-| linuxParameters | Linux-specific modifications that are applied to the container, such as Linux KernelCapabilities | `map(string)` | `{}` | no |
+| linuxParameters | Linux-specific modifications that are applied to the container, such as Linux KernelCapabilities | `any` | `{}` | no |
 | logConfiguration | The log configuration specification for the container | `map(string)` | `{}` | no |
 | memory | The hard limit (in MiB) of memory to present to the container | `number` | `0` | no |
 | memoryReservation | The soft limit (in MiB) of memory to reserve for the container | `number` | `0` | no |
-| mountPoints | The mount points for data volumes in your container | `list(string)` | `[]` | no |
+| mountPoints | The mount points for data volumes in your container | `list(any)` | `[]` | no |
 | name | The name of a container | `string` | `""` | no |
 | network\_mode | The Docker networking mode to use for the containers in the task | `string` | `"bridge"` | no |
 | pid\_mode | The process namespace to use for the containers in the task | `string` | `"host"` | no |
 | placement\_constraints | An array of placement constraint objects to use for the task | `list(string)` | `[]` | no |
-| portMappings | The list of port mappings for the container | `list(string)` | `[]` | no |
+| portMappings | The list of port mappings for the container | `list(any)` | `[]` | no |
 | privileged | When this parameter is true, the container is given elevated privileges on the host container instance (similar to the root user) | `bool` | `false` | no |
 | pseudoTerminal | When this parameter is true, a TTY is allocated | `bool` | `false` | no |
 | readonlyRootFilesystem | When this parameter is true, the container is given read-only access to its root file system | `bool` | `false` | no |
@@ -153,9 +153,9 @@ By default, this module creates a task definition with a single container defini
 | systemControls | A list of namespaced kernel parameters to set in the container | `list(string)` | `[]` | no |
 | tags | The metadata that you apply to the task definition to help you categorize and organize them | `map(string)` | `{}` | no |
 | task\_role\_arn | The short name or full Amazon Resource Name (ARN) of the IAM role that containers in this task can assume | `string` | `""` | no |
-| ulimits | A list of ulimits to set in the container | `list(string)` | `[]` | no |
+| ulimits | A list of ulimits to set in the container | `list(any)` | `[]` | no |
 | user | The user name to use inside the container | `string` | `""` | no |
-| volumes | A list of volume definitions in JSON format that containers in your task may use | `list(string)` | `[]` | no |
+| volumes | A list of volume definitions in JSON format that containers in your task may use | `list(any)` | `[]` | no |
 | volumesFrom | Data volumes to mount from another container | `list(string)` | `[]` | no |
 | workingDirectory | The working directory in which to run commands inside the container | `string` | `""` | no |
 
diff --git a/examples/ecs_update_service.tf b/examples/ecs_update_service.tf
index 039fb60..46d7f19 100644
--- a/examples/ecs_update_service.tf
+++ b/examples/ecs_update_service.tf
@@ -8,7 +8,10 @@
 #
 #  $ terraform taint null_resource.update-service
 
-provider "aws" {}
+provider "aws" {
+  region  = "us-east-1"
+  version = "~> 2.0"
+}
 
 module "mongo-task-definition" {
   source = "github.com/mongodb/terraform-aws-ecs-task-definition"
@@ -28,12 +31,12 @@ module "mongo-task-definition" {
 resource "aws_ecs_service" "mongo" {
   cluster         = "mongo"
   name            = "mongo"
-  task_definition = "${module.mongo-task-definition.arn}"
+  task_definition = module.mongo-task-definition.arn
 }
 
 resource "null_resource" "update-service" {
   triggers = {
-    arn = "${module.mongo-task-definition.arn}"
+    arn = module.mongo-task-definition.arn
   }
 
   provisioner "local-exec" {
diff --git a/examples/terraform-task-definition-multiple-containers/main.tf b/examples/terraform-task-definition-multiple-containers/main.tf
index ba5bf94..a7a4715 100644
--- a/examples/terraform-task-definition-multiple-containers/main.tf
+++ b/examples/terraform-task-definition-multiple-containers/main.tf
@@ -38,12 +38,12 @@ module "merged" {
   source = "../../modules/merge"
 
   container_definitions = [
-    "${module.mongodb.container_definitions}",
-    "${module.redis.container_definitions}",
+    module.mongodb.container_definitions,
+    module.redis.container_definitions,
   ]
 }
 
 resource "aws_ecs_task_definition" "ecs_task_definition" {
-  container_definitions = "${module.merged.container_definitions}"
+  container_definitions = module.merged.container_definitions
   family                = "app"
 }
diff --git a/modules/merge/variables.tf b/modules/merge/variables.tf
index f66e9ca..5a8959b 100644
--- a/modules/merge/variables.tf
+++ b/modules/merge/variables.tf
@@ -1,5 +1,4 @@
 variable "container_definitions" {
   default     = []
   description = "A list of container definitions in JSON format that describe the different containers that make up your task"
-  type        = "list"
 }
diff --git a/variables.tf b/variables.tf
index 764d2bb..0020b5c 100644
--- a/variables.tf
+++ b/variables.tf
@@ -50,7 +50,7 @@ variable "entryPoint" {
 variable "environment" {
   default     = []
   description = "The environment variables to pass to a container"
-  type        = list(string)
+  type        = list(map(string))
 }
 
 variable "essential" {
@@ -76,7 +76,7 @@ variable "family" {
 variable "healthCheck" {
   default     = {}
   description = "The health check command and associated configuration parameters for the container"
-  type        = map(string)
+  type        = any
 }
 
 variable "hostname" {
@@ -108,7 +108,7 @@ variable "links" {
 variable "linuxParameters" {
   default     = {}
   description = "Linux-specific modifications that are applied to the container, such as Linux KernelCapabilities"
-  type        = map(string)
+  type        = any
 }
 
 variable "logConfiguration" {
@@ -130,7 +130,7 @@ variable "memoryReservation" {
 variable "mountPoints" {
   default     = []
   description = "The mount points for data volumes in your container"
-  type        = list(string)
+  type        = list(any)
 }
 
 variable "name" {
@@ -157,7 +157,7 @@ variable "placement_constraints" {
 variable "portMappings" {
   default     = []
   description = "The list of port mappings for the container"
-  type        = list(string)
+  type        = list(any)
 }
 
 variable "privileged" {
@@ -224,7 +224,7 @@ variable "task_role_arn" {
 variable "ulimits" {
   default     = []
   description = "A list of ulimits to set in the container"
-  type        = list(string)
+  type        = list(any)
 }
 
 variable "user" {
@@ -235,7 +235,7 @@ variable "user" {
 variable "volumes" {
   default     = []
   description = "A list of volume definitions in JSON format that containers in your task may use"
-  type        = list(string)
+  type        = list(any)
 }
 
 variable "volumesFrom" {
@@ -248,4 +248,3 @@ variable "workingDirectory" {
   default     = ""
   description = "The working directory in which to run commands inside the container"
 }
-