# AWS Elastic Container Service (ECS) Node Executor

Available in PagerDuty Process Automation Commercial products.

# About Amazon ECS

Amazon ECS is a fully managed container orchestration service that makes it easy for users to deploy, manage, and scale containerized applications.

AWS Fargate is a serverless compute engine that is compatible with both Amazon Elastic Container Service (ECS) and Amazon Elastic Kubernetes Service (EKS).

# About the ECS Node Executor

The Amazon ECS Node Executor provides the ability to send commands to one or multiple containers running on ECS.

Sending commands to ECS containers makes it easier to collect diagnostic information and quickly troubleshoot errors. In development, this allows users to easily interact with various processes in your containers and troubleshoot applications. In production scenarios, this enables break-glass access to containers to debug issues.

This plugin is designed to work in conjunction with the ECS-Fargate Node Source.

# Configuration

# Configure ECS Task and Service Definitions

Attach a Task IAM Role to the Task Definition that grants containers the permissions needed for communication between the managed SSM agent (execute-command agent) and the SSM service. Use the following policy and attach it to the task definition as explained here .

{
   "Version": "2012-10-17",
   "Statement": [
       {
       "Effect": "Allow",
       "Action": [
            "ssmmessages:CreateControlChannel",
            "ssmmessages:CreateDataChannel",
            "ssmmessages:OpenControlChannel",
            "ssmmessages:OpenDataChannel"
       ],
      "Resource": "*"
      }
   ]
}

Enable remote commands by adding the --enable-execute-command flag to one of the following AWS CLI Commands: create-service, update-service, start-task, or run-task. For example, with an existing Service:
```
 aws ecs create-service \
     --cluster cluster-name \
     --task-definition task-definition-name \
     --enable-execute-command \
     --service-name service-name \
     --desired-count 1
```

[Optional] If the task definition parameter initProcessEnabled is set to true, this starts the init process inside the container, which removes any zombie SSM agent child processes found. The following provides an example:

{
    "taskRoleArn": "ecsTaskRole",
    "networkMode": "awsvpc",
    "requiresCompatibilities": [
        "EC2",
        "FARGATE"
    ],
    "executionRoleArn": "ecsTaskExecutionRole",
    "memory": ".5 gb",
    "cpu": ".25 vcpu",
    "containerDefinitions": [
        {
            "name": "amazon-linux",
            "image": "amazonlinux:latest",
            "essential": true,
            "command": ["sleep","3600"],
            "linuxParameters": {
                "initProcessEnabled": true
            }
        }
    ],
    "family": "ecs-exec-task"
}

# Configure IAM Policy for Process Automation

# Authentication

Follow the instructions outlined in the AWS Plugins Overview for Process Automation to authenticate with AWS.

When defining the IAM Role for Runbook Automation or Process Automation, be sure to include the following permissions in the Policy associated with the role:

ecs:ExecuteCommand

This IAM policy condition key can be used in tandem with other IAM policy condition keys to limit the access that Process Automation has within ECS:

aws:ResourceTag/clusterTagKey
ecs:ResourceTag/clusterTagKey
aws:ResourceTag/taskTagKey
ecs:ResourceTag/taskTagKey
ecs:container-name
ecs:cluster
ecs:task
ecs:enable-execute-command

Examples of IAM policies that restrict the access by Process Automation can be found here (opens new window).

# Executing Commands

In order to send commands to ECS Containers, first configure the ECS-Fargate Node Source. This retrieves the ECS containers and presents them as nodes in Process Automation:

Once the containers have been added as nodes, Process Automation can send commands to them. This can be done through the Commands tab, or using the Remote Command Job step:

# Ad-hoc Commands through the Commands Tab

Navigate to the Commands tab in the sidebar menu.
In the Node Filter field, type in a Node Filter to specify the containers that the command should execute on. For example, ECS:Container-Image: spring.* filters only the containers where the container image starts with spring:
In the Enter a command field, provide the command to be executed on the filtered containers. Click on Run on 1 Node.

# Remote Command Job Step

In a new or existing Job, click on Add a step.
In the Node Steps tab, click on Command.
Provide the command to send to the container and click Save to save the Job step:
Towards the top of the page, click on the Nodes tab to modify the target Nodes for the Job.
The toggle should be set to Dispatch to Nodes.
In the Node Filter field, provide a filter that selects the containers that the commands should be executed on. For example, ECS:Container-Image: spring.*:
Click Save at the bottom of the page to save the Job configuration.

# Example Job: Java Thread Dump from ECS Container

A sample implementation of executing commands on ECS containers can be seen in our Automated Diagnostics Solution.

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