Setup vscode ssh remote to a private EC2 instance via ssm

Summary

With AWS system manager (SSM), it is possible to setup vscode ssh remote to a EC2 in a private subnet, and without open 22 port. GitHub,

• Setup a connection to a private EC2 via SSM
• Setup vscode ssh remote to the EC2 by proxyCommand
• Create the infrastructure by a CDK stack

Reference

• vscode cloud9 setup
• SSM VPC endpoint
• aws ssm start-session

Architecture

CDK Stack

• create a VPC with a S3 VPC endpoint

    const vpc = new aws_ec2.Vpc(
      this,
      'VpcWithS3Endpoint',
      {
        gatewayEndpoints: {
          S3: {
            service: aws_ec2.GatewayVpcEndpointAwsService.S3
          }
        }
      }
    )

• add system manager VPC interface endpoint

    vpc.addInterfaceEndpoint(
      'VpcIterfaceEndpointSSM',
      {
        service: aws_ec2.InterfaceVpcEndpointAwsService.SSM
      }
    )

• create an IAM role for the EC2

    const role = new aws_iam.Role(
      this,
      'RoleForEc2ToAccessS3',
      {
        roleName: 'RoleForEc2ToAccessS3',
        assumedBy: new aws_iam.ServicePrincipal('ec2.amazonaws.com'),
      }
    )

• role for EC2 to communicate with SSM

    role.addManagedPolicy(
      aws_iam.ManagedPolicy.fromManagedPolicyArn(
        this,
        'PolicySSMMangerAccessS3',
        'arn:aws:iam::aws:policy/AmazonSSMManagedInstanceCore'
      )
    )

• policy for EC2 to access S3

    role.attachInlinePolicy(
      new aws_iam.Policy(
        this,
        'PolicyForEc2AccessS3',
        {
          policyName: 'PolicyForEc2AccessS3',
          statements: [
            new aws_iam.PolicyStatement(
              {
                actions: ['s3:*'],
                resources: ['*']
              }
            ),
          ]
        }
      )
    )

• launch an EC2 in a private subnet

    const ec2 = new aws_ec2.Instance(
      this,
      'Ec2ConnectVpcEndpointS3',
      {
        role: role,
        keyName: 'hai_ec2_t4g_large',
        vpc: vpc,
        instanceName: 'Ec2ConnectVpcEndpointS3',
        instanceType: aws_ec2.InstanceType.of(aws_ec2.InstanceClass.T2, aws_ec2.InstanceSize.SMALL),
        machineImage: aws_ec2.MachineImage.latestAmazonLinux(),
        securityGroup: sg,
        vpcSubnets: {
          subnetType: aws_ec2.SubnetType.PRIVATE
        }
      }
    )

Setup a connection to private EC2 via SSM

• follow this to install ssm plugin for the local machine

• start a ssm session from the local machine
  

aws ssm start-session --target "EC2-INSTANCE-ID"

Setup vscode ssh remote to the EC2

• follow this to nstall ssh remote extension for vscode

• generate SSH key pair from the local machine
  

ssh-keygen -b 4096 -C 'VS Code Remote SSH user' -t rsa

• configure the ~/.ssh/config file

Host ssm-private-ec2
  IdentityFile ~/.ssh/id_rsa
  HostName i-026bb5f5caaf16aa1
  User ec2-user
  ProxyCommand sh -c "~/.ssh/ssm-private-ec2-proxy.sh %h %p"

• create a ssm-private-ec2-proxy.sh file

#!/bin/bash

AWS_PROFILE=''
AWS_REGION=''
MAX_ITERATION=5
SLEEP_DURATION=5

# Arguments passed from SSH client
HOST=$1
PORT=$2

echo $HOST

# Start ssm session
aws ssm start-session --target $HOST \
  --document-name AWS-StartSSHSession \
  --parameters portNumber=${PORT} \
  --profile ${AWS_PROFILE} \
  --region ${AWS_REGION}

vscode will create a ssh connection to the EC2 via the ProxyCommand script which creates a SSM session under the hood. This is the way vscode ssh remote with cloud9 works