ECS Cluster

By default, the ECS cluster UFO uses is whatever UFO_ENV is set to. Since the default UFO_ENV=dev, this means the ECS cluster named “dev” will be used. You can override this setting.

Cluster Setting


Ufo.configure do |config|
  config.ecs.cluster = ":ENV-cluster"

Here we’re overriding the cluster name with :ENV-cluster. The setting is a pattern that UFO expands. When UFO_ENV=dev

:ENV-cluster => dev-cluster

So ufo will deploy your application to the ECS cluster name “dev-cluster”.

Deployment Configuration

The ecs.maximum_percent and ecs.minimum_healthy_percent can be set to control the rolling deploy percentages. Example:

Ufo.configure do |config|
  config.ecs.maximum_percent = 300
  config.ecs.minimum_healthy_percent = 100

Important: You should not set the ecs.maximum_percent to below 200 if you only have 1 container and want it to able to scale to 2. See: Debugging Deployment Configuration.

Cluster Setting as Callable Option

This is an advanced technique. For really custom control, you can also assign config.ecs.cluster a Ruby object that implements the .call method. Example:


class ClusterName
  def call(names)
    case names.env
    when "prod"
    when "dev", "sbx", "uat"

Ufo.configure do |config|
  config.ecs.cluster = ClusterName # implements call method

When UFO_ENV=prod, the ECS Service uses the prod-cluster. When the UFO_ENV is dev, sbx, or uat, the the dev-cluster. And for other UFO_ENV values, the qa-cluster is used.

Note, the names argument is an instance of the Ufo::Names class.


The table below covers each setting. Each option is configured in .ufo/config.rb with config.OPTION. The config. portion is not shown for conciseness. IE: logger.level vs config.logger.level.

Name Default Description
ecs.cluster :ENV Notice that the default is a pattern. By default, the :ENV pattern is expanded as the value of env var UFO_ENV=dev. So, by convention, the ECS cluster that ufo deploys to matches the UFO_ENV. If UFO=prod, then ufo ship deploys to the prod ECS cluster. This is option overrides this convention.
ecs.deployment_configuration nil Full control over the DeploymentConfiguration.This option is passed straight through to the CloudFormation template, so you should use CamelCase for the keys. Also when used, overrides ecs.maximum_percent and ecs.minimum_healthy_percent.
ecs.desired_count. nil Only respected when autoscaling.enabled = false.
ecs.maximum_percent 200 Upper limit on the number of tasks in a service that are allowed in the RUNNING or PENDING state during a deployment. This is part of DeploymentConfiguration.
ecs.minimum_healthy_percent 100 Lower limit on the number of tasks in a service that must remain in the RUNNING state during a deployment. This is part of DeploymentConfiguration.
ecs.scheduling_strategy REPLICA ECS Scheduling Strategy. IE: REPLICA or DAEMON

See Full Config Reference