Cannot access web server inside ec2 - amazon-web-services

Question

I am learning AWS and is trying to setup a web server on ec2, but I can't access the web server from outside even after I tried everything I can think of.
Here is the cloudformation template I am using:
AWSTemplateFormatVersion: "2010-09-09"
Resources:
## VPC
# Create a VPC
HelloVpc:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
EnableDnsHostnames: "true"
EnableDnsSupport: "true"
Tags:
- Key: Name
Value: HelloVpc
# Create internet gateway for public subnet
HelloInternetGateway:
Type: AWS::EC2::InternetGateway
Properties:
Tags:
- Key: Name
Value: HelloInternetGateway
HelloVPCGatewayAttachment:
Type: AWS::EC2::VPCGatewayAttachment
Properties:
VpcId:
Ref: HelloVpc
InternetGatewayId:
Ref: HelloInternetGateway
# Create route table for public subnet
HelloPublicRouteTable:
Type: AWS::EC2::RouteTable
Properties:
Tags:
- Key: Name
Value: HelloPublicRouteTable
VpcId:
Ref: HelloVpc
HelloInternetGatewayRoute:
Type: AWS::EC2::Route
Properties:
RouteTableId:
Ref: HelloPublicRouteTable
DestinationCidrBlock: 0.0.0.0/0
GatewayId:
Ref: HelloInternetGateway
# create subnets
HelloVpcPrivateSubNet:
Type: AWS::EC2::Subnet
Properties:
VpcId:
Ref: HelloVpc
AvailabilityZone: { "Fn::Select": [0, { "Fn::GetAZs": "" }] }
CidrBlock: 10.0.2.0/24
Tags:
- Key: Name
Value: HelloVpcPrivateSubNet
HelloVpcPublicSubNet:
Type: AWS::EC2::Subnet
Properties:
VpcId:
Ref: HelloVpc
AvailabilityZone: { "Fn::Select": [1, { "Fn::GetAZs": "" }] }
CidrBlock: 10.0.1.0/24
Tags:
- Key: Name
Value: HelloVpcPublicSubNet
HelloPublicSubnetRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId:
Ref: HelloPublicRouteTable
SubnetId:
Ref: HelloVpcPublicSubNet
## Security group
HelloSecurityGroup:
Type: AWS::EC2::SecurityGroup
Properties:
GroupDescription: Allow http and ssh
VpcId:
Ref: HelloVpc
SecurityGroupIngress:
- IpProtocol: tcp
FromPort: 22
ToPort: 22
CidrIp: 0.0.0.0/0
- IpProtocol: tcp
FromPort: 5000
ToPort: 5000
CidrIp: 0.0.0.0/0
SecurityGroupEgress:
- IpProtocol: tcp
FromPort: 22
ToPort: 22
CidrIp: 0.0.0.0/0
- IpProtocol: tcp
FromPort: 5000
ToPort: 5000
CidrIp: 0.0.0.0/0
## EC2
HelloEc2Instance:
Type: AWS::EC2::Instance
Properties:
ImageId: ami-0c91eefc31e3b0867
InstanceType: t3.nano
KeyName: EC2-KP
NetworkInterfaces:
- AssociatePublicIpAddress: "true"
DeviceIndex: "0"
SubnetId:
Ref: HelloVpcPublicSubNet
GroupSet:
- Ref: HelloSecurityGroup
Then I SSH into the instance and started a web server with
mkdir app
cd app
dotnet new web
dotnet run
which starts a web server on port 5000 and curl http://localhost:5000 works fine.
Since I can ssh into the instance, the ACL and security group should be correct. I googled around and tried to disable the firewall with
sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT
sudo iptables -F
but it still doesn't work.
At this point, I really have no idea what goes wrong. Can anyone please help?

Answer 1

The problem is that dotnet run causes your app to listen on localhost, so it's only reachable locally within the server itself.
You need it to bind to the public IP of the server, which you can do as follows:
dotnet run --urls http://0.0.0.0:5000
For additional options to set the URL, see here.