Terraform 0.11 - Share complex attribute values between resources

Question

I'm currently writing multiple AWS Kinesis Data Analytics applications with Terraform. Both applications share the same Kinesis input stream and thus have the same schema:

resource "aws_kinesis_analytics_application" "example1" {
  name = "example1"

  inputs {
    # SHARE THIS ATTRIBUTE VALUE WITH example2
    schema {
      record_columns {
        mapping  = "$.FIELD1"
        name     = "FIELD1"
        sql_type = "VARCHAR(32)"
      }

      record_columns {
        mapping  = "$.FIELD2"
        name     = "FIELD2"
        sql_type = "VARCHAR(32)"
      }

      record_format {
        mapping_parameters {
          json {
            record_row_path = "$"
          }
        }
      }

    }
  }

  outputs {
    # other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code ...."
}

resource "aws_kinesis_analytics_application" "example2" {
  name = "example2"

  inputs {
    # SHARE THIS ATTRIBUTE VALUE WITH example1
    schema {
      record_columns {
        mapping  = "$.FIELD1"
        name     = "FIELD1"
        sql_type = "VARCHAR(32)"
      }

      record_columns {
        mapping  = "$.FIELD2"
        name     = "FIELD2"
        sql_type = "VARCHAR(32)"
      }

      record_format {
        mapping_parameters {
          json {
            record_row_path = "$"
          }
        }
      }

    }
  }

  outputs {
    # Other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code...."
}

I'm assuming that this is possible if there is a data source available for schema:

data "aws_kinesis_analytics_application_schema" "example_input" {
      record_columns {
        mapping  = "$.FIELD1"
        name     = "FIELD1"
        sql_type = "VARCHAR(32)"
      }

      record_columns {
        mapping  = "$.FIELD2"
        name     = "FIELD2"
        sql_type = "VARCHAR(32)"
      }

      record_format {
        mapping_parameters {
          json {
            record_row_path = "$"
          }
        }
      }
}

resource "aws_kinesis_analytics_application" "example1" {
  name = "example1"

  inputs {
    # Other attributes
    schema = "${data.aws_kinesis_analytics_application_schema.example_input}"
  }

  outputs {
    # other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code ...."
}

resource "aws_kinesis_analytics_application" "example2" {
  name = "example2"

  inputs {
    # Other attributes
    schema = "${data.aws_kinesis_analytics_application_schema.example_input}"
  }

  outputs {
    # Other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code...."
}

However, there is no data source available for this specific attribute of this resource. Is it possible to share such a complex attribute between resources without using a data source?

markvdlaan93 markvdlaan93 · Accepted Answer · 2020-01-11T14:20:43

You can use variables for that:

variable schema {
   record_columns = [
      {....},
      {....}
   ]
   record_format {
      mappings_parameters = [
         {....}
      ]
   }
}

resource "aws_kinesis_analytics_application" "example1" {
  name = "example1"

  inputs {
    schema = "${var.schema}"
  }

  outputs {
    # other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code ...."
}

resource "aws_kinesis_analytics_application" "example2" {
  name = "example2"

  inputs {
    # SHARE THIS ATTRIBUTE VALUE WITH example1
    schema = "${var.schema}"
  }

  outputs {
    # Other attributes

    schema {
      record_format_type = "JSON"
    }
  }

  code = "SQL code...."
}

Terraform 0.11 - Share complex attribute values between resources

1 Answers