Terraform: Configuring Private IP Addresses on aws instance

[changwuf31]

Hi,

Suppose I configure aws_instance with count = 5,
how can I assign ip addresses on these instances ?

[knuckolls]

I have not personally done this, but I believe this is how something like that is meant to be done. You'll use a variable that has a map of values:

variable "ips" {
    default = {
        0 = "10.1.1.5"
        1 = "10.1.1.6"
        ...
    }
}

and then look them up via an interpolation function within your aws_instance provider:

resource "aws_instance" "example" {
  ...
  count = 5
  private_ip = "lookup(ips,count.index)"
  ...
}

The syntax above might not be exactly right, but it's close.

[changwuf31]

@knuckolls: Thanks a lot! It works !!!

For the record, the correct syntax is like this:

variable "ips" {
    default = {
        "0" = "10.1.1.5"
        "1" = "10.1.1.6"
        ...
    }
}

And

resource "aws_instance" "example" {
  ...
  count = 5
  private_ip = "${lookup(ips,count.index)}"
  ...
}

Should I close this ? I think this should go to the docs though..

[phinze]

Glad you got this figured out!

I think this should go to the docs though..

Agreed. The pieces are mentioned under Interpolation Syntax and called out when describing count meta-parameter but it seems like the pattern is common enough to call out specifically somewhere.

[cnoffsin]

I copied this code directly into my code and it didn't work and I realize this issue is 2 years old.

For someone who got here from google searching the syntax that does work here is:

private_ip = "${lookup(var.data_node_ips,count.index)}"

[scotthesterberg]

Just wanted comment for those who run across this currently what works now (terraform 0.12.x) is:

lookup(var.ips,count.index)

[hashibot[bot]]

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