Module: ecs-alb-service-task

Terraform module to create an ECS Service for a web app (task), and an ALB target group to route requests.

Usage

For a complete example, see examples/complete.

For automated test of the complete example using bats and Terratest, see test.

provider "aws" {
  region = var.region
}

module "label" {
  source     = "git::https://github.com/cloudposse/terraform-null-label.git?ref=tags/0.15.0"
  namespace  = var.namespace
  name       = var.name
  stage      = var.stage
  delimiter  = var.delimiter
  attributes = var.attributes
  tags       = var.tags
}

module "vpc" {
  source     = "git::https://github.com/cloudposse/terraform-aws-vpc.git?ref=tags/0.8.1"
  namespace  = var.namespace
  stage      = var.stage
  name       = var.name
  delimiter  = var.delimiter
  attributes = var.attributes
  cidr_block = var.vpc_cidr_block
  tags       = var.tags
}

module "subnets" {
  source               = "git::https://github.com/cloudposse/terraform-aws-dynamic-subnets.git?ref=tags/0.16.1"
  availability_zones   = var.availability_zones
  namespace            = var.namespace
  stage                = var.stage
  name                 = var.name
  attributes           = var.attributes
  delimiter            = var.delimiter
  vpc_id               = module.vpc.vpc_id
  igw_id               = module.vpc.igw_id
  cidr_block           = module.vpc.vpc_cidr_block
  nat_gateway_enabled  = true
  nat_instance_enabled = false
  tags                 = var.tags
}

resource "aws_ecs_cluster" "default" {
  name = module.label.id
  tags = module.label.tags
}

module "container_definition" {
  source                       = "git::https://github.com/cloudposse/terraform-aws-ecs-container-definition.git?ref=tags/0.21.0"
  container_name               = var.container_name
  container_image              = var.container_image
  container_memory             = var.container_memory
  container_memory_reservation = var.container_memory_reservation
  container_cpu                = var.container_cpu
  essential                    = var.container_essential
  readonly_root_filesystem     = var.container_readonly_root_filesystem
  environment                  = var.container_environment
  port_mappings                = var.container_port_mappings
  log_configuration            = var.container_log_configuration
}

module "ecs_alb_service_task" {
  source = "cloudposse/ecs-alb-service-task/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"
  namespace                          = var.namespace
  stage                              = var.stage
  name                               = var.name
  attributes                         = var.attributes
  delimiter                          = var.delimiter
  alb_security_group                 = module.vpc.vpc_default_security_group_id
  container_definition_json          = module.container_definition.json
  ecs_cluster_arn                    = aws_ecs_cluster.default.arn
  launch_type                        = var.ecs_launch_type
  vpc_id                             = module.vpc.vpc_id
  security_group_ids                 = [module.vpc.vpc_default_security_group_id]
  subnet_ids                         = module.subnets.public_subnet_ids
  tags                               = var.tags
  ignore_changes_task_definition     = var.ignore_changes_task_definition
  network_mode                       = var.network_mode
  assign_public_ip                   = var.assign_public_ip
  propagate_tags                     = var.propagate_tags
  health_check_grace_period_seconds  = var.health_check_grace_period_seconds
  deployment_minimum_healthy_percent = var.deployment_minimum_healthy_percent
  deployment_maximum_percent         = var.deployment_maximum_percent
  deployment_controller_type         = var.deployment_controller_type
  desired_count                      = var.desired_count
  task_memory                        = var.task_memory
  task_cpu                           = var.task_cpu
}

The container_image in the container_definition module is the Docker image used to start a container.

The container_definition is a string of JSON-encoded container definitions. Normally, you would place only one container definition here as the example above demonstrates. However, there might be situations where more than one container per task is more appropriate such as optionally in Fargate or in other cases where sidecars may be required. With cloudposse/terraform-aws-ecs-container-definition multi-container task definitions can be created using:

module "ecs_alb_service_task" {
  ...
  container_definition_json = jsonencode([
    module.first_container.json_map_object,
    module.second_container.json_map_object,
  ])
  ...
}

Refer to the multiple definitions example in cloudposse/terraform-aws-ecs-container-definition for details on defining multiple definitions.

This string is passed directly to the Docker daemon. Images in the Docker Hub registry are available by default. Other repositories are specified with either repository-url/image:tag or repository-url/image@digest. Up to 255 letters (uppercase and lowercase), numbers, hyphens, underscores, colons, periods, forward slashes, and number signs are allowed. This parameter maps to Image in the Create a container section of the Docker Remote API and the IMAGE parameter of docker run.

When a new task starts, the Amazon ECS container agent pulls the latest version of the specified image and tag for the container to use. However, subsequent updates to a repository image are not propagated to already running tasks.

Images in Amazon ECR repositories can be specified by either using the full registry/repository:tag or registry/repository@digest. For example, 012345678910.dkr.ecr.<region-name>.amazonaws.com/<repository-name>:latest or 012345678910.dkr.ecr.<region-name>.amazonaws.com/<repository-name>@sha256:94afd1f2e64d908bc90dbca0035a5b567EXAMPLE.

Images in official repositories on Docker Hub use a single name (for example, ubuntu or mongo).

Images in other repositories on Docker Hub are qualified with an organization name (for example, amazon/amazon-ecs-agent).

Images in other online repositories are qualified further by a domain name (for example, quay.io/assemblyline/ubuntu).

For more info, see Container Definition.