Cannot reach YUM repos on terraform EC2 instances - amazon-web-services

Question

background:
I used terraform to build an AWS autoscaling group with a few instances spread across availability zones and linked by a load balancer. Everything is created properly, but the load balancer has no valid targets because they're nothing listening on port 80.
Fine, I thought. I'll install NGINX and throw up a basic config.
expected behavior
instances should be able to reach yum repos
actual behavior
I'm unable to ping anything or run any of the package manager commands, getting the following error
Could not retrieve mirrorlist https://amazonlinux-2-repos-us-east-2.s3.dualstack.us-east-2.amazonaws.com/2/core/latest/x86_64/mirror.list error was
12: Timeout on https://amazonlinux-2-repos-us-east-2.s3.dualstack.us-east-2.amazonaws.com/2/core/latest/x86_64/mirror.list: (28, 'Failed to connect to amazonlinux-2-repos-us-east-2.s3.dualstack.us-east-2.amazonaws.com port 443 after 2700 ms: Connection timed out')
One of the configured repositories failed (Unknown),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:
1. Contact the upstream for the repository and get them to fix the problem.
2. Reconfigure the baseurl/etc. for the repository, to point to a working
upstream. This is most often useful if you are using a newer
distribution release than is supported by the repository (and the
packages for the previous distribution release still work).
3. Run the command with the repository temporarily disabled
yum --disablerepo=<repoid> ...
4. Disable the repository permanently, so yum won't use it by default. Yum
will then just ignore the repository until you permanently enable it
again or use --enablerepo for temporary usage:
yum-config-manager --disable <repoid>
or
subscription-manager repos --disable=<repoid>
5. Configure the failing repository to be skipped, if it is unavailable.
Note that yum will try to contact the repo. when it runs most commands,
so will have to try and fail each time (and thus. yum will be be much
slower). If it is a very temporary problem though, this is often a nice
compromise:
yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true
Cannot find a valid baseurl for repo: amzn2-core/2/x86_64
troubleshooting steps taken
I'm new to Terraform, and I'm still having issues doing the automated provisioning of user_data, so I SSH'd into the instance. The instance is set up in a public subnet with an auto-provisioned public IP. Below is the code for the security groups.
resource "aws_security_group" "elb_webtrafic_sg" {
name = "elb-webtraffic-sg"
description = "Allow inbound web trafic to load balancer"
vpc_id = aws_vpc.main_vpc.id
ingress {
description = "HTTPS trafic from vpc"
from_port = 443
to_port = 443
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
ingress {
description = "HTTP trafic from vpc"
from_port = 80
to_port = 80
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
ingress {
description = "allow SSH"
from_port = 22
to_port = 22
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
egress {
description = "all traffic out"
from_port = 0
to_port = 0
protocol = "-1"
cidr_blocks = ["0.0.0.0/0"]
}
tags = {
Name = "elb-webtraffic-sg"
}
}
resource "aws_security_group" "instance_sg" {
name = "instance-sg"
description = "Allow traffic from load balancer to instances"
vpc_id = aws_vpc.main_vpc.id
ingress {
description = "web traffic from load balancer"
security_groups = [ aws_security_group.elb_webtrafic_sg.id ]
from_port = 80
to_port = 80
protocol = "tcp"
}
ingress {
description = "web traffic from load balancer"
security_groups = [ aws_security_group.elb_webtrafic_sg.id ]
from_port = 443
to_port = 443
protocol = "tcp"
}
ingress {
description = "ssh traffic from anywhere"
from_port = 22
to_port = 22
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
egress {
description = "all traffic to load balancer"
security_groups = [ aws_security_group.elb_webtrafic_sg.id ]
from_port = 0
to_port = 0
protocol = "-1"
}
tags = {
Name = "instance-sg"
}
}
#this is a workaround for the cyclical security group id call
#I would like to figure out a way for this to destroy this first
#it currently takes longer to destroy than to set up
#terraform hangs because of the dependancy each SG has on each other,
#but will eventually struggle down to this rule and delete it, clearing the deadlock
resource "aws_security_group_rule" "elb_egress_to_webservers" {
security_group_id = aws_security_group.elb_webtrafic_sg.id
type = "egress"
source_security_group_id = aws_security_group.instance_sg.id
from_port = 80
to_port = 80
protocol = "tcp"
}
resource "aws_security_group_rule" "elb_tls_egress_to_webservers" {
security_group_id = aws_security_group.elb_webtrafic_sg.id
type = "egress"
source_security_group_id = aws_security_group.instance_sg.id
from_port = 443
to_port = 443
protocol = "tcp"
}
Since I was able to SSH into the machine, I tried to set up the web instance security group to allow direct connection from the internet to the instance. Same errors: cannot ping outside web addresses, same error on YUM commands.
I can ping the default gateway in each subnet. 10.0.0.1, 10.0.1.1, 10.0.2.1.
Here is the routing configuration I currently have setup.
resource "aws_vpc" "main_vpc" {
cidr_block = "10.0.0.0/16"
tags = {
Name = "production-vpc"
}
}
resource "aws_key_pair" "aws_key" {
key_name = "Tanchwa_pc_aws"
public_key = file(var.public_key_path)
}
#internet gateway
resource "aws_internet_gateway" "gw" {
vpc_id = aws_vpc.main_vpc.id
tags = {
Name = "internet-gw"
}
}
resource "aws_route_table" "route_table" {
vpc_id = aws_vpc.main_vpc.id
route {
cidr_block = "0.0.0.0/0"
gateway_id = aws_internet_gateway.gw.id
}
tags = {
Name = "production-route-table"
}
}
resource "aws_subnet" "public_us_east_2a" {
vpc_id = aws_vpc.main_vpc.id
cidr_block = "10.0.0.0/24"
availability_zone = "us-east-2a"
tags = {
Name = "Public-Subnet us-east-2a"
}
}
resource "aws_subnet" "public_us_east_2b" {
vpc_id = aws_vpc.main_vpc.id
cidr_block = "10.0.1.0/24"
availability_zone = "us-east-2b"
tags = {
Name = "Public-Subnet us-east-2b"
}
}
resource "aws_subnet" "public_us_east_2c" {
vpc_id = aws_vpc.main_vpc.id
cidr_block = "10.0.2.0/24"
availability_zone = "us-east-2c"
tags = {
Name = "Public-Subnet us-east-2c"
}
}
resource "aws_route_table_association" "a" {
subnet_id = aws_subnet.public_us_east_2a.id
route_table_id = aws_route_table.route_table.id
}
resource "aws_route_table_association" "b" {
subnet_id = aws_subnet.public_us_east_2b.id
route_table_id = aws_route_table.route_table.id
}
resource "aws_route_table_association" "c" {
subnet_id = aws_subnet.public_us_east_2c.id
route_table_id = aws_route_table.route_table.id
}