Demo Resource Attributes

Welcome to this tutorial on working with resource attributes in OpenTofu. You’ll learn how to:

• Inspect an existing configuration (domain.tf)
• Understand and list exported attributes of the time_static resource
• Reference those attributes in another resource (local_file)
• Initialize and apply your configuration
• Verify the final state

1. Inspect domain.tf

Navigate to your project folder and open the domain.tf file:

cd /root/opentofu-projects/project-chronos
nano domain.tf

Inside, you’ll see an empty time_static resource block:

resource "time_static" "time_update" {
}

Resource Type: time_static

2. What Is time_static?

The time_static resource generates a fixed timestamp on apply. You don’t need to pass any arguments—OpenTofu handles everything.

3. Exported Attributes of time_static

According to the time_static documentation, the following attributes are available:

4. Reference a time_static Attribute

To reference the id (RFC3339) of your time_update resource:

time_static.time_update.id

You can inject this into any other resource’s argument or output.

5. Write the Timestamp to a Local File

Open main.tf and add a local_file resource that writes the timestamp to /root/time.txt:

resource "time_static" "time_update" {
}

resource "local_file" "time" {
  filename = "/root/time.txt"
  content  = "Timestamp of this file: ${time_static.time_update.id}"
}

6. Initialize and Apply

Run the following commands:

opentofu init
opentofu apply

Confirm both resources are created successfully:

• time_static.time_update
• local_file.time

7. Inspect the Applied Resources

Use opentofu show to inspect the resource state:

$ opentofu show

# local_file.time:
resource "local_file" "time" {
  filename = "/root/time.txt"
  content  = "Timestamp of this file: 2024-04-09T09:52:41Z"
  id       = "f095dbo698d1e64f847e39f01fc9f7d4592ff48"
}

# time_static.time_update:
resource "time_static" "time_update" {
  id      = "2024-04-09T09:52:41Z"
  rfc3339 = "2024-04-09T09:52:41Z"
  day     = 9
  month   = 4
  year    = 2024
  hour    = 9
  minute  = 52
  second  = 41
  unix    = 1712656361
}

Question: What is the id of local_file.time?
Answer: f095dbo698d1e64f847e39f01fc9f7d4592ff48

8. Retrieve the rfc3339 Timestamp

From the same output, you can also see:

rfc3339 = "2024-04-09T09:52:41Z"

Question: What is the rfc3339 value?
Answer: 2024-04-09T09:52:41Z

9. Final Configuration Snapshot

After apply, your resources look like this:

resource "local_file" "time" {
  filename = "/root/time.txt"
  content  = "Timestamp of this file: ${time_static.time_update.id}"
}

resource "time_static" "time_update" {
  day     = 9
  month   = 4
  year    = 2024
  hour    = 9
  minute  = 52
  second  = 41
  unix    = 1712656361
  id      = "2024-04-09T09:52:41Z"
  rfc3339 = "2024-04-09T09:52:41Z"
}

That wraps up this demo on using resource attributes in OpenTofu. Happy provisioning!

Links and References

• OpenTofu Documentation: https://docs.opentofu.org/
• time_static resource
• OpenTofu CLI Reference