This simple bash script can be used to get the public and private IP addresses of the Tasks within a Fargate Cluster. With the CLUSTER_NAME defined as an environment variable, this script will iterate through all of the Tasks in a Cluster and create a .env file with both the public and private addresses of the Tasks.

#!/bin/bash

> taskIps.env

TASK_LIST=$(aws ecs list-tasks --cluster $CLUSTER_NAME)
TASK_ARNS=$(echo "$TASK_LIST" | jq -r '.taskArns[]')

while IFS= read -r TASK_ARN; do
    NETWORK_INTERFACE_ID=$(aws ecs describe-tasks --cluster $CLUSTER_NAME --tasks "$TASK_ARN" --query 'tasks[0].attachments[0].details[?name==`networkInterfaceId`].value' --output text)
    PRIVATE_IP=$(aws ecs describe-tasks --cluster $CLUSTER_NAME --tasks "$TASK_ARN" --query 'tasks[0].attachments[0].details[?name==`privateIPv4Address`].value' --output text)
    PUBLIC_IP=$(aws ec2 describe-network-interfaces --network-interface-ids "$NETWORK_INTERFACE_ID" --query 'NetworkInterfaces[*].Association.PublicIp' --output text)
    TASK_NAME=$(aws ecs describe-tasks --cluster $CLUSTER_NAME --tasks "$TASK_ARN" --query 'tasks[0].containers[0].name' --output text | tr '[:lower:]' '[:upper:]')
    echo "${TASK_NAME}_PUBLIC_IP=$PUBLIC_IP" >> taskIps.env
    echo "${TASK_NAME}_PRIVATE_IP=$PRIVATE_IP" >> taskIps.env
done <<< "$TASK_ARNS"

The basic steps involved:

• Get the Tasks in the Cluster
• Get the ARNs of the Tasks
• Loop through the Task ARNs
  • Get the Network Interface ID of the Task using the Task ARN and Cluster Name
  • Get the Private IP using the Task ARN and Cluster Name
  • Get the Public IP using the Network Interface ID
  • Get the Task Name from the Task ARN and Cluster Name
  • Write everything to the the .env file

GitHub Gist

https://gist.github.com/schuettc/5e805ec2ca6c21f9b3af3f9cfa75fade