Pulumi create instance in existing subnet - pulumi

Question

I am trying to create an EC2 instance from a custom vpc. I have vpc as Output. But i want to assign to string. Would appreciate help in this context.
Option 1:
const vpcId = args.network.vpc.id.apply(id => id); //type Output<string>; network extends awsx:Vpc
const mySubnet = aws.ec2.gtSubnet({
availabilityZone: 'ap-southeast-2a',
filters: [
{ name: "tag:Name", values: ["*private-0"]}
],
vpcId: vpcId; //Error: Type 'Output<string>' is not assignable to type 'string'
});
this.vm = new aws.ec2.Instance("ec2Instance", {
ami: amiId,
instanceType: instanceClass,
networkInterfaces: [{
networkInterfaceId: networkInterface.id,
deviceIndex: 0,
}]
});
Option 2:
const sg = new awsx.ec2.SecurityGroup("webserver-sg", { vpc }); //Here again I need vpcid string in the SecurityGroupArgs

Answer 1

Output<T> is a promise, also called a future. It's a value that's not yet available. It will be available when the Pulumi engine starts executing. You can pass a callback which will be run when the value is available (and you'll immediately get a new promise for the new, not-yet-available return value of the callback) or you can pass it to methods which will accept a promise (these usually take Input<T>).
Unfortunately, getSubnet (currently) does not accept Input or Promise, so option #2 is out.
What you can do is:
const mySubnetId = args.network.vpc.id.apply(id => {
const getSubnetResult = aws.ec2.getSubnet({
vpcId: id;
})
return getSubnetResult.id
})
This will give you an Output<string> which you can pass to new Instance({subnetId: ...}) because it accepts an Input<string>.