Terraform syntax for putting json as value in a map

Question

I'm new to terraform. I have a json object that I need to set as the value in a terraform map so that the resource gets created with the json as the value.

The .tf file looks like this in that section:

...

      config_overrides = {
        override_1      = "True"
        override_2      = '{"key1":"val1","key2":"val2"}' #this is the json object
    }

...

However, the terraform lint command terraform lint -check is failing on the json object.

$ terraform fmt -check

Error: Invalid character

  on myterraform.tf line 28, in resource <<resource name>> :
  28:         override_2 = '{"key1":"val1","key2":"val2"}'

Single quotes are not valid. Use double quotes (") to enclose strings.


Error: Invalid expression

  on myterraform.tf line 28, in resource <<resource name>>:
  28:         override_2 = '{"key1":"val1","key2":"val2"}'

Expected the start of an expression, but found an invalid expression token.

I have tried many different variations and cant get the linter to accept it. Please advise.

Answer 1

You can use Terraform's jsonencode function so that Terraform itself is responsible for generating the JSON and you only need to worry about the data structure:

  override_2 = jsonencode({
    "key1": "val1",
    "key2": "val2",
  })

Terraform's object expression syntax happens to be similar to JSON's and so the argument to jsonencode here looks a lot like the JSON string it'll convert to, but that is really just a normal Terraform expression and so you can include any Terraform expression constructs in there. For example:

  override_2 = jsonencode({
    "key1": "val1",
    "key2": var.any_variable,
  })

Answer 2

You will need to use the \ in the value ' isn't going to work.

config_overrides = {
  override_1 = "True"
  override_2 = "{\"key1\":\"val1\",\"key2\":\"val2\"}"
}