terraform-aws-ecs-app-scheduler

This terraform module is an AWS ECS Application Module for Scheduler without an Application Load Balancer(ALB), designed to be used with DNXLabs/terraform-aws-ecs.

The following resources will be created:

• IAM roles - The cloudwatch event needs an IAM Role to run the ECS task definition. A role is created and a policy will be granted via IAM policy.

• IAM policy - Policy to be attached to the IAM Role. This policy will have a trust with the cloudwatch event service. And it will use the managed policy AmazonEC2ContainerServiceEventsRole created by AWS.

• Cloudwatch Log Groups

  • You can specify the number of days you want to retain log events in the specified log group. Possible values are: 1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, and 3653.
  • Export to a S3 Bucket - Whether to mark the log group to export to an S3 bucket (needs the module terraform-aws-log-exporter (https://github.com/DNXLabs/terraform-aws-log-exporter) to be deployed in the account/region)

• ECS task definition - A task definition is required to run Docker containers in Amazon ECS. Some of the parameters you can specify in a task definition include:

  • Image - Docker image to deploy
    • Default Value = "alpine:latest"
  • CPU - Hard limit of the CPU for the container
    • Default Value = 0
  • Memory - Hard memory of the container
    • Default Value = 512
  • Name - Name of the ECS Service
  • Set log configuration

• ECS Task-scheduler activated by cloudwatch events

• Cron expression - You can create rules that self-trigger on an automated schedule in CloudWatch Events using cron or rate expressions. All scheduled events use UTC time zone and the minimum precision for schedules is 1 minute.

Resources

1. Cloudwatch Events
2. Cron expression
3. IAM role
4. IAM policy
5. Cloudwatch Log Group
6. ECS task definition

Resources definition

Cloudwatch Events

Amazon CloudWatch Events delivers a near real-time stream of system events that describe changes in Amazon Web Services (AWS) resources. Using simple rules that you can quickly set up, you can match events and route them to one or more target functions or streams. CloudWatch Events becomes aware of operational changes as they occur. CloudWatch Events responds to these operational changes and takes corrective action as necessary, by sending messages to respond to the environment, activating functions, making changes, and capturing state information.

Cloudwatch Events documentation

Cron expression

You can create rules that self-trigger on an automated schedule in CloudWatch Events using cron or rate expressions. All scheduled events use UTC time zone and the minimum precision for schedules is 1 minute.

Schedule expressions

Iam Role

The cloudwatch event needs an IAM Role to run the ECS task definition. A role is created and a policy will be granted via IAM policy.

IAM Policy

Policy to be attached to the IAM Role. This policy will have a trust with the cloudwatch event service. And it will use the managed policy AmazonEC2ContainerServiceEventsRole created by AWS.

Cloudwatch Log Group

A log group is a group of log streams that share the same retention, monitoring, and access control settings. You can define log groups and specify which streams to put into each group. There is no limit on the number of log streams that can belong to one log group.

Log Groups

Task Definition

A task definition is required to run Docker containers in Amazon ECS. Some of the parameters you can specify in a task definition include:

• The Docker image to use with each container in your task
• How much CPU and memory to use with each task or each container within a task
• The launch type to use, which determines the infrastructure on which your tasks are hosted
• The Docker networking mode to use for the containers in your task
• The logging configuration to use for your tasks
• Whether the task should continue to run if the container finishes or fails
• The command the container should run when it is started
• Any data volumes that should be used with the containers in the task
• The IAM role that your tasks should use

Task definitions

Usage

module "example" {
  source               = "git::https://github.com/DNXLabs/terraform-aws-ecs-app-scheduler?ref=0.0.2"
  name                 = "example"
  vpc_id               = data.aws_vpc.selected.id # From DNXLabs/terraform-aws-ecs
  cluster_name         = module.ecs_apps.ecs_name # From DNXLabs/terraform-aws-ecs
  service_role_arn     = module.ecs_apps.ecs_service_iam_role_arn # From DNXLabs/terraform-aws-ecs
  task_role_arn        = module.ecs_apps.ecs_task_iam_role_arn # From DNXLabs/terraform-aws-ecs
  memory               = 512
  schedule_expression  = "0/30 * * * ? *" # it will trigger the task every 30 minutes https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/ScheduledEvents.html
  account_id           = var.aws_account_id
}

Requirements

Name	Version
terraform	>= 0.12.0

Providers

Name	Version
aws	n/a

Inputs

Name	Description	Type	Default	Required
account_id	n/a	any	n/a	yes
cloudwatch_logs_export	Whether to mark the log group to export to an S3 bucket (needs terraform-aws-log-exporter to be deployed in the account/region)	bool	false	no
cloudwatch_logs_retention	Specifies the number of days you want to retain log events in the specified log group. Possible values are: 1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, and 3653.	number	120	no
cluster_name	n/a	string	"Name of existing ECS Cluster to deploy this app to"	no
cpu	Hard limit for CPU for the container	string	"0"	no
event_description	n/a	string	"ECS task"	no
iam_path	n/a	string	"/"	no
image	Docker image to deploy (can be a placeholder)	string	"alpine:latest"	no
launch_type	Instance type. Fargate allowed	string	"EC2"	no
memory	Hard memory of the container	string	"512"	no
name	Name of your ECS service	any	n/a	yes
rule_enabled	Whether the rule should be enabled	bool	true	no
schedule_expression	Cron expression	any	n/a	yes
service_role_arn	Existing service role ARN created by ECS cluster module	any	n/a	yes
task_role_arn	Existing task role ARN created by ECS cluster module	any	n/a	yes
vpc_id	VPC ID to deploy this app to	any	n/a	yes

Outputs

Name	Description
aws_cloudwatch_log_group_arn	n/a

Authors

Module managed by DNX Solutions.

License

Apache 2 Licensed. See LICENSE for full details.