The previous page has 5 dynamic resources but nothing is done with them. To access an attribute of a resource, just... access it.

Accessing an attribute in Pretf will not return the actual dynamic value of the resource managed by Terraform. Instead, it returns an interpolation reference string for Terraform to use when it runs.


from pretf.api import block

def pretf_blocks():
    animals = ["dog", "cat", "buffalo", "rabbit", "badger"]
    for name in animals:
        animal = yield block("resource", "random_integer", name, {
            "min": 1,
            "max": 10,
        yield block("output", name, {
            "value": animal.result,  # access "result" attribute of resource

Now run pretf plan/apply and state will contain the additional outputs. animal.result was translated into "${}" for the dog iteration of the loop, and Terraform used that to output the actual value.

Accessing any attribute of a block object will return a string containing a Terraform reference to that attribute. This lets you take advantage of Terraform's implicit resource dependencies.

Assign and yield

The above code contains the pattern result = yield block(...).

Pretf sends yielded values back to generators. This allows functions assign block objects to a variable and yield them in the same line.

Reference without yielding

If something is defined in another file, but you still want to reference it, then create a block object with an empty body. Do not yield it, because that would include it in the *.tf.json output.

yield block("output", name, {
    "value": block("resource", "random_integer", name, {}).result,