Terraform AWS EC2 how to login with ssh pub file

Question

Here's the terraform snippet

resource "aws_security_group" "ec2_sg" {
  name = "ec2-access"
  vpc_id = aws_vpc.main.id

  ingress {
    from_port = 22
    to_port   = 22
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]  # Allow SSH from anywhere (adjust for security)
  }

  egress {
    from_port = 0
    to_port   = 0
    protocol = "-1"
    cidr_blocks = ["0.0.0.0/0"]  # Allow all outbound traffic (adjust for security)
  }
}

resource "aws_key_pair" "ssh-key" {
  key_name   = "ssh-key"
  public_key = "ssh-rsa AAAAB3NzaC1..."
}

# EC2 Instance in Public Subnet
resource "aws_instance" "ec2" {
  ami           = "ami-04b70fa74e45c3917" # Noble Numbat 24.04 LTS
  instance_type = "t2.micro"
  subnet_id     = aws_subnet.public.id
  security_groups = [aws_security_group.ec2_sg.id]
  associate_public_ip_address = true
  key_name         = "ssh-key"
}

And the terraform apply command creates the EC2 without error.

But then I try to ssh into the machine with ssh -i "~/.ssh/id_rsa.pub" <ec2 public address>

It gives error:

The authenticity of host 'ip.add.re.ss (ip.add.re.ss)' can't be established. ED25519 key fingerprint is SHA256:Q47dOukdKpdYhysUMwAEkxkIyz8AcGGawdx9fYjHxH4. This key is not known by any other names Are you sure you want to continue connecting (yes/no/[fingerprint])? yes Warning: Permanently added 'ip.add.re.ss' (ED25519) to the list of known hosts. [email protected]: Permission denied (publickey).

I guess I am misconfiguring the EC2?

Answer 1

The AMI ID says that it's a Ubuntu Linux, which means the default user name is ubuntu. That also means that the entire command should be:

ssh -i "~/.ssh/id_rsa" ubuntu@<ec2 public address>

The list of default users for different types of AMIs is in the AWS docs.