I have an application(runs at http://localhost:8080) that talks to a backend api which runs at http://localhost:8081. I have dockerized the frontend and the backend separately and running them through docker-compose locally works perfectly without any issues. But, when I run it in ECS, the frontend couldn't find http://localhost:8081(backend).
I am using an AutoScaling group with an Elastic Load Balancer and I have my both containers defined in a single Task Definition. Also, I have the backend linked to the front end. When I ssh into my ECS instance and run docker ps -a i can see both of my containers are running at the correct ports exactly like in my local machine(Result of docker ps -a) and I can successfully ping each of them from one container to the other.
Task Definition
"CartTaskDefinition": {
"Type": "AWS::ECS::TaskDefinition",
"Properties": {
"ContainerDefinitions": [
{
"Name": "cs-cart",
"Image": "thishandp7/cs-cart",
"Memory": 400,
"PortMappings":[
{
"ContainerPort": "8080",
"HostPort": "8080"
}
],
"Links": [
"cs-server"
]
},
{
"Name": "cs-server",
"Image": "thishandp7/cs-server",
"Memory": 450,
"PortMappings":[
{
"ContainerPort": "8081",
"HostPort": "8081"
}
],
}
]
}
}
Listeners in my ElasticLoadBalancer, The first listener is for the frontend and the second one is for the backend
"Listeners" : [
{
"LoadBalancerPort": 80,
"InstancePort": 8080,
"Protocol": "http"
},
{
"LoadBalancerPort": 8081,
"InstancePort": 8081,
"Protocol": "tcp"
}
],
EC2 instacne security Group Ingress rules:
"SecurityGroupIngress" : [
{
"IpProtocol" : "tcp",
"FromPort" : 8080,
"ToPort" : 8080,
"SourceSecurityGroupId" : { "Ref": "ElbSecurityGroup" }
},
{
"IpProtocol" : "tcp",
"FromPort" : 8081,
"ToPort" : 8081,
"SourceSecurityGroupId" : { "Ref": "ElbSecurityGroup" }
},
{
"IpProtocol" : "tcp",
"FromPort" : 22,
"ToPort" : 22,
"CidrIp" : "0.0.0.0/0"
}
],
Docker Compose
version: "3.5"
services:
cart:
build:
context: ..
dockerfile: docker/Dockerfile
args:
APP_LOCATION: /redux-saga-cart/
PORT: 8080
networks:
- server-cart
ports:
- 8080:8080
depends_on:
- server
server:
build:
context: ..
dockerfile: docker/Dockerfile
args:
APP_LOCATION: /redux-saga-shopping-cart-server/
PORT: 8081
ports:
- 8081:8081
networks:
- server-cart
networks:
server-cart:
Quick update: I have tried it with awsvpc network mode with application load balancer. Still not working
Thanks in advance.
What kind of Docker Network mode are you using(Brdige/Host) on ECS?. I don't think localhost will work properly on ECS containers. I had same issue so I used private IP or DNS name of EC2 host for my communication as temp testing purpose. Ex - http://10.0.1.100:8081.
Note - Please make sure to give security group rule to allow 8081 traffic from within EC2(Edit EC2 security group to allow 8081 from same sgid as source).
For Production deployments, I would recommend to use a service discovery to identify the backend service(Consul by Hashicorp) or AWS Private Service Discovery on ECS.
-- Update --
Since you are running both containers under same task def(under same ECS service), so typically ECS will bring both docker containers on same host. Do something like following.