terraform/website/docs/configuration/functions/csvdecode.html.md

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functions	csvdecode function	docs-funcs-encoding-csvdecode	The csvdecode function decodes CSV data into a list of maps.

base64decode Function

csvdecode decodes a string containing CSV-formatted data and produces a list of maps representing that data.

CSV is Comma-separated Values, an encoding format for tabular data. There are many variants of CSV, but this function implements the format defined in RFC 4180.

The first line of the CSV data is interpreted as a "header" row: the values given are used as the keys in the resulting maps. Each subsequent line becomes a single map in the resulting list, matching the keys from the header row with the given values by index. All lines in the file must contain the same number of fields, or this function will produce an error.

Examples

> csvdecode("a,b,c\n1,2,3\n4,5,6")
[
  {
    "a" = 1
    "b" = 2
    "c" = 3
  },
  {
    "a" = 4
    "b" = 5
    "c" = 6
  }
]

Use with the count meta-argument

It can be tempting to use csvdecode to generate a set of similar resources using the count meta-argument, as in this example:

locals {
  instances = csvdecode(file("${path.module}/instances.csv"))
}

resource "aws_instance" "example" {
  count = len(local.instances) # Beware! (see below)

  instance_type = local.instances[count.index].instance_type
  ami           = local.instances[count.index].ami
}

The above example will work on initial creation, but if any rows are removed from the CSV file, or if the records in the CSV file are re-ordered, Terraform will not understand that the ordering has changed and will instead interpret this as requests for changes to many or all of the instances, which will in turn force these instances to be destroyed and re-created.

The above pattern can be used with care in situations where, for example, the CSV file is only ever appended to, or if mass-updating the resources would not be harmful, but in general we recommend avoiding the above pattern.