create-cluster.sh

#!/bin/bash
#
# Creates an ECS Cluster

# check for all required variables
if [ "$KEY_NAME" == '' ]; then
  echo "Please specify KEY_NAME and provide the filename (without the path and extension)"
  exit 1
fi
if [ "$SECURITY_GROUP" == '' ]; then
  echo "Please set a SECURITY_GROUP from your VPC (e.g. sg-12345678)"
  exit 2
fi
if [ "$VPC_ID" == '' ]; then
  echo "ECS requires using a VPC, so you must specify a VPC_ID"
  exit 3
fi
if [ "$CLUSTER" == '' ]; then
  echo "Please specify CLUSTER"
  exit 4
fi

# Step 1 - Check all optional variables
if [ "$INSTANCE_TYPE" == '' ]; then
  INSTANCE_TYPE=t3.small
fi
if [ "$INSTANCE_COUNT" == '' ]; then
  INSTANCE_COUNT=1
fi
if [ "$SUBNET_ID" == '' ]; then
  SUBNET_ID=$(aws ec2 describe-subnets --filters Name=vpc-id,Values=$VPC_ID --query 'Subnets[*].[SubnetId]' --output text | tr '\n' ',')
fi

# Step 2 - Create our ECS Cluster with INSTANCE_COUNT instances
echo "Detecting existing cluster/$CLUSTER"
CONTAINER_INSTANCE_COUNT=$(aws ecs describe-clusters --cluster $CLUSTER \
  --query 'clusters[*].[registeredContainerInstancesCount]' --output text)
if [ "$CONTAINER_INSTANCE_COUNT" == $INSTANCE_COUNT ]; then
  echo "Using existing cluster/$CLUSTER"
else
  if [ "$CONTAINER_INSTANCE_COUNT" != '0' ]; then
    echo "Instance count is $CONTAINER_INSTANCE_COUNT, but requested instance count is $INSTANCE_COUNT"
  fi
  echo "Creating cluster/$CLUSTER"
  # to create
  ecs-cli up --cluster $CLUSTER --size $INSTANCE_COUNT --capability-iam --instance-type $INSTANCE_TYPE --keypair $KEY_NAME \
    --security-group $SECURITY_GROUP --vpc $VPC_ID --subnets $SUBNET_ID --force --verbose
fi

echo "Complete"