For our EC2 instances, we give them a name (which is also the hostname) that combines a common string, ie ‘vault-’, suffixed by the first few characters of the EC2 instance id. For example:
A vault server with EC2 instance id “i-ab12356afe” would be designated “vault-ab1235”. I’m having a hard time because I have to repeat the same code throughout my aws_instance resource declaration, ie in the provisioners:
${var.node_short_name}-${substr(self.id, 2, 6)}
In addition to DRY, I would really like to be able to export/output this value from the module that creates the aws_instance so that it can be used elsewhere, ie to create/destroy a DNS record.
I think because the instance-id isn’t known until after the instance is created is maybe why I’m having such a hard time with this? At least how I’ve tried to use them, local and null_data_source both create cyclic dependencies.
Is there some way to construct this string just once, and then use that result as both a value in the provisioners and export it as an output value?
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