[aws-ec2] Support Amazon Linux 2

[0xdevalias]

Currently we can use AmazonLinuxEdition with options of Standard or Minimal:

• https://awslabs.github.io/aws-cdk/refs/_aws-cdk_aws-ec2.html#amazonlinuxedition-enum

This doesn't seem to allow us to use Amazon Linux 2 though:

• https://aws.amazon.com/amazon-linux-2/

When I deployed a test ec2 instance using machineImage: new ec2.AmazonLinuxImage(), then attempted to use amazon-linux-extras I got an error:

/var/lib/cloud/instance/scripts/part-001: line 4: amazon-linux-extras: command not found

The reported versions were:

Amazon Linux AMI release 2018.03
Kernel 4.14.62-65.117.amzn1.x86_64 on an x86_64

The used AMI ID was ami-09b42976632b27e9b, which maps to:

• https://aws.amazon.com/amazon-linux-ami/2018.03-release-notes/

The Amazon Linux 2 AMI ID's are listed here:

• https://aws.amazon.com/amazon-linux-2/release-notes/#Amazon_Linux_2_AMI_IDs

It would seem we can probable use GenericLinuxImage, passing it an appropriate amiMap, but it isn't immediately obvious what this amiMap should look like (region to AMI ID perhaps?).

• https://awslabs.github.io/aws-cdk/refs/_aws-cdk_aws-ec2.html#genericlinuximage

It looks like older versions of the documentation actually had better usage text for this..

• https://awslabs.github.io/aws-cdk/versions/0.8.1/refs/_aws-cdk_aws-ec2.html#amis

It looks like in the latest version, that now lives under autoscaling:

• https://awslabs.github.io/aws-cdk/refs/_aws-cdk_aws-autoscaling.html#amis

Perhaps some better documentation cross references to make discoverability easier? I wouldn't immediately think I need to go look at autoscaling when I am thinking about setting up an EC2 instance for example.

So with that, it seems that I could get my Amazon Linux 2 images with code such as the following:

// amzn2-ami-hvm-2.0.20181024-x86_64-gp2
// Ref: https://aws.amazon.com/amazon-linux-2/release-notes/#Amazon_Linux_2_AMI_IDs
const amazonLinux2Gp2 = new ec2.GenericLinuxImage({
    'ap-northeast-1': 'ami-00f9d04b3b3092052',
    'ap-northeast-2': 'ami-0c764df09c35858b8',
    'ap-northeast-3': 'ami-0f4865fb90390aeec',
    'ap-south-1': 'ami-00796998f258969fd',
    'ap-southeast-1': 'ami-085fd1bd447be68e8',
    'ap-southeast-2': 'ami-0b8dea0e70b969adc',
    'ca-central-1': 'ami-05cac140c6a1fb960',
    'cn-north-1': 'ami-0bcb2d94a820e559c',
    'cn-northwest-1': 'ami-0d82dd087e5eea5af',
    'eu-central-1': 'ami-02ea8f348fa28c108',
    'eu-west-1': 'ami-0a5e707736615003c',
    'eu-west-2': 'ami-017b0e29fac27906b',
    'eu-west-3': 'ami-04992646d54c69ef4',
    'sa-east-1': 'ami-0160a8b6087883cb6',
    'us-east-1': 'ami-013be31976ca2c322',
    'us-east-2': 'ami-0350c5670171b5391',
    'us-gov-west-1': 'ami-d263f9b3',
    'us-west-1': 'ami-01beb64058d271bc4',
    'us-west-2': 'ami-061e7ebbc234015fe',
});