Docker service is accessible from EC2 Instance (localhost) but not remotely

Question

I have a docker container running a .NET WebAPI. I have configured the container to running using the.network mode "host". The reason for this is that I have a MySQL Database running on the same EC2 Instance, but not containerized:

services:
  api:
    image: <<>>
    restart: always
    network_mode: host

I am able to access the service with wget:

Resolving localhost (localhost)... 127.0.0.1
Connecting to localhost (localhost)|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 200 OK

However I am unable to access the same when attempting to connect using my EC2 Instance public endpoint. I have made sure that the EC2 Instance security group is allowing HTTP/HTTPS traffic:

Any suggestions on how to resolve this?

Answer 1

You need to check your service is running on 127.0.0.1 or 0.0.0.0 . 127.0.0.1 is loopback ip address. You can not access 127.0.0.1 from external. EC2 instances has more than one ip addresses.

For more details check here

Answer 2

I resolved this by adding an iptables rule to allow traffic on port 80. I've never had to do this but there you go.