Hi folks New around here wave Here s a replica of an EC2 Ins

Question

Hi folks New around here wave Here s a replica of an EC2 Instance with which I m working ```const amznAmi = aws getAmiOutput filters name name values amzn2 ami kernel owners 137112412989 NOTE this is Amazon s Owner ID for Official Amazon managed AMIs mostRecent true snip const instance = new aws ec2 Instance customName ami pulumi interpolate`$ amznAmi id ` instanceType t2 medium networkInterfaces networkInterfaceId networkInterface id deviceIndex 0 userData userData keyName some key tags Name customName rootBlockDevice volumeSize 400 ``` This builds fine on initial stack buildouts but whenever Amzn publishes a new Amzn Linux 2 AMI I run into an issue where pulumi can t create the right update strategy The AMI triggers a replacement of the EC2 Instance see the entire preview below with show replacement steps on ``` Type Name Plan Info pulumi pulumi Stack infra dev 1 warning + aws ec2 Instance instance replace diff ~ami ``` But there are resources that helped build that instance like `networkInterface` that don t get neatly detached ```aws ec2 Instance instance error 1 error occurred creating EC2 Instance InvalidNetworkInterface InUse Interface eni lt snip gt in use status code 400 request id lt snip gt ``` My question is how can I best tell Pulumi what my ideal update strategy is when a field that triggers replacement e g `ami` on a resource inevitably is different In particular with EC2 I would want Pulumi to stop the EC2 instance gt detach the NetworkInterface gt terminate the old instance gt create a new EC2 with the new AMI and current `userData` gt re attach the NetworkInterface

little-cartoon-10569 · Answer

You can use the dependsOn opt if it s not already inferred I thought ENIs are though

little-cartoon-10569 · Answer

However if you don t need to explicitly define the ENI then you shouldn t AWS will create and manage one for you You can get its ID from the instance s outputs if you need it

swift-whale-31925 · Answer

yeah I ve tried various `CustomResourceOptions` `dependsOn` `parent` etc Instead of handling that flow above they offer this preview ``` Type Name Plan Info pulumi pulumi Stack infra dev 1 warning aws ec2 NetworkInterface networkInterface + aws ec2 Instance instance create aws ec2 Instance instance delete```

little-cartoon-10569 · Answer

After re reading you can t get Pulumi to detach ENIs There is no support for this sort of thing You would need to do this yourself Pulumi can delete it for you and create a new one

swift-whale-31925 · Answer

ahhhh I see But if I hand over the mgmt of making the ENI to Amazon Amazon will take care of it on replacement

swift-whale-31925 · Answer

or it should do so anyway

little-cartoon-10569 · Answer

Yes I ve never had an issue with ENIs They re essentially atomic within the instances

swift-whale-31925 · Answer

so instead of trying something like this to give the instance an EIP I could instead just set something like and Amazon should understand iirc

little-cartoon-10569 · Answer

I don t see a need for an explicit ENI in that first example And I don t see a need for a public IP address either If you need a specific private IP address use `privateIp` If you don t need a specific IP address don t provide one let AWS pick one for you This is much safer

little-cartoon-10569 · Answer

Assuming that the only things that will connect to your EC2 instance are set up in Pulumi just get the IP address from the created resource You hopefully shouldn t have to define the IP address in advance

swift-whale-31925 · Answer

this has been working great for me thanks < little cartoon 10569> slightly smiling face