Write a shell script file on bastion host create using CDK - amazon-web-services

Question

In AWS, to gain access to our RDS instance we setup a dedicated EC2 bastion host that we securely access by invoking the SSM Agent in the EC2 dashboard.
This is done by writing a shell script after connecting to the bastion host, now the script usually disappears after a certain time(?). So, is there any way to create this file using CDK when I create the bastion host?
I tried using CFN.init but to no avail.
this.bastionHost = new BastionHostLinux(this, "BastionHost", {
vpc: inspireStack.vpc,
subnetSelection: { subnetType: SubnetType.PRIVATE_WITH_NAT },
instanceType: InstanceType.of(InstanceClass.T2, InstanceSize.MICRO),
init: CloudFormationInit.fromConfigSets({
configSets: {
default: ["install"],
},
configs: {
install: new InitConfig([
InitCommand.shellCommand("cd ~"),
InitFile.fromString("jomar.sh", "testing 123"),
InitCommand.shellCommand("chmod +x jomar.sh"),
]),
},
})

Answer 1

You can write files to an EC2 instance with cloud-init. Either from an existing file or directly from the TS (a json for instance)
const ec2Instance = new ec2.Instance(this, 'Instance', {
vpc,
instanceType: ec2.InstanceType.of(
ec2.InstanceClass.T4G,
ec2.InstanceSize.MICRO,
),
machineImage: new ec2.AmazonLinuxImage({
generation: ec2.AmazonLinuxGeneration.AMAZON_LINUX_2,
cpuType: ec2.AmazonLinuxCpuType.ARM_64,
}),
init: ec2.CloudFormationInit.fromConfigSets({
configSets: {
default: ['install', 'config'],
},
configs: {
install: new ec2.InitConfig([
ec2.InitFile.fromObject('/etc/config.json', {
IP: ec2Eip.ref,
}),
ec2.InitFile.fromFileInline(
'/etc/install.sh',
'./src/asteriskConfig/install.sh',
),
ec2.InitCommand.shellCommand('chmod +x /etc/install.sh'),
ec2.InitCommand.shellCommand('cd /tmp'),
ec2.InitCommand.shellCommand('/etc/install.sh'),
]),
config: new ec2.InitConfig([
ec2.InitFile.fromFileInline(
'/etc/asterisk/pjsip.conf',
'./src/asteriskConfig/pjsip.conf',
),
https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_ec2.CloudFormationInit.html

Answer 2

I see there are three simple workarounds:
SSM start session contains 'profile' section, where you can add your script as a bash function.
You can create an SSM document that will create this file, so before starting the session you will only need to run this document to create a file...
Save this script on S3 and just download them
Regarding disappearing file - it's strange... This CDK construct is similar to Instance, try to use it instead, and create your script with user-data.