time_rotating constantly re-creates resource after rfc3339 + rotation_xy has passed the first time.

[m273d15]

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Terraform Version

Terraform v0.15.4
on darwin_amd64
+ provider registry.terraform.io/hashicorp/time v0.7.1

Affected Resource(s)

• time_rotating

Terraform Configuration Files

resource "time_rotating" "test" {
  rfc3339          = "2021-06-20T12:43:13Z"
  rotation_minutes = 7
}

Debug Output

Output

> terraform apply -auto-approve
time_rotating.test: Refreshing state... [id=2021-06-20T12:43:13Z]

Note: Objects have changed outside of Terraform

Terraform detected the following changes made outside of
Terraform since the last "terraform apply":

  # time_rotating.test has been deleted
  - resource "time_rotating" "test" {
      - day              = 20 -> null
      - hour             = 12 -> null
      - id               = "2021-06-20T12:43:13Z" -> null
      - minute           = 43 -> null
      - month            = 6 -> null
      - rfc3339          = "2021-06-20T12:43:13Z" -> null
      - rotation_minutes = 7 -> null
      - rotation_rfc3339 = "2021-06-20T12:50:13Z" -> null
      - second           = 13 -> null
      - unix             = 1624192993 -> null
      - year             = 2021 -> null
    }

Unless you have made equivalent changes to your
configuration, or ignored the relevant attributes using
ignore_changes, the following plan may include actions to
undo or respond to these changes.

──────────────────────────────────────────────────────────

Terraform used the selected providers to generate the
following execution plan. Resource actions are indicated
with the following symbols:
  + create

Terraform will perform the following actions:

  # time_rotating.test will be created
  + resource "time_rotating" "test" {
      + day              = (known after apply)
      + hour             = (known after apply)
      + id               = (known after apply)
      + minute           = (known after apply)
      + month            = (known after apply)
      + rfc3339          = "2021-06-20T12:43:13Z"
      + rotation_minutes = 7
      + rotation_rfc3339 = (known after apply)
      + second           = (known after apply)
      + unix             = (known after apply)
      + year             = (known after apply)
    }

Plan: 1 to add, 0 to change, 0 to destroy.
time_rotating.test: Creating...
time_rotating.test: Creation complete after 0s [id=2021-06-20T12:43:13Z]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Panic Output

Expected Behavior

• The resource is created after the first call of terraform apply and not created again before the date rfc3339 + rotation_minutes (in the example above: 2021-06-20T12:50:13Z) has passed.
• After the date has passed the next call of terraform apply will re-create the resource. If I call terraform apply again the resource should not be re-created as long as the current date is lower than the next rotation date (would be rfc3339 + rotation_minutes * 2)

short:

• tf init
• tf apply -> initial create
• tf apply -> nop
• tf apply -> nop
• time has passed rfc3339 + rotation_minutes
• tf apply -> re-create resource
• tf apply -> nop
• time has passed rfc3339 + rotation_minutes * 2
• tf apply -> re-create resource
• tf apply -> nop
  ...

Actual Behavior

• As expected: The resource is created after the first call of terraform apply and not created again before the date rfc3339 + rotation_minutes (in the example above: 2021-06-20T12:50:13Z) has passed.
• After the date has passed each call of terraform apply leads to the re-creation of the resource.

short:

• tf init
• tf apply -> initial create
• tf apply -> nop
• tf apply -> nop
• time has passed rfc3339 + rotation_minutes
• tf apply -> re-create resource
• tf apply -> re-create resource
• tf apply -> re-create resource
• tf apply -> re-create resource
  ...

Steps to Reproduce

With the example above it should be enough to call:

0. terraform init
1. terraform apply - initial creation
2. terraform apply - re-creation

Important Factoids

References

• #0000

Thank you for your work on Terraform ❤️

[m273d15]

Can someone confirm this issue? Is this a bug or a lack of documentation? It does work as expected without the rfc3339.

[carldjohnston]

I'm experiencing this issue too.

My assumption was that the rfc3339 argument was setting the initial time for calculating the rotation time, after which the rotation_X argument would become the increment and the resource would be recreated every N rotation_X's time.

I can't see how the actual behaviour is useful.

[davidcorrigan714]

This really needs to be fixed. I think what needs to happen is that the provider should compare the id to rotation_rfc3339 and not rotate if it's past it.

[mikew3432]

At the moment the time_rotating doesn't work like a clock.
"if timestamp()>rotation_rfc3339 then delete the resource"
and then terraform says
"the resource does not exist - create from code"
and the provider says simply
"rotation_rfc3339 = rfc3339 + rot_X rotation interval "

The rotation_rfc3339 calculation is too simple and with a fixed rfc3339 ends up constantly in the past, resulting in the Delete -> create identically on every Apply to infinity. Why not have some clock arithmetic, it could be a switch like
clock_rotating = true

To illustrate what we want, I think,

if rfc3339 input is not null,
if rfc3339 input in the past, we want this:

    v rfc3339                                   v id             v rotation_rfc3339
    |             |             |               |         x      |
                  ^+1rot_X      ^+2rot_X       ^+Nrot_X   ^timestamp()

if rfc3339 input in the future, we want this:

                      v id
                      v rfc3339     v rotation_rfc3339
|         x           |             |                    |
          ^timestamp()              ^+1rot_X

So could it be coded like this?

if (rfc3339 input)
  rfc3339 = rfc3339 input 
  if (rfc3339 in the past)
    id = timestamp() minus ( (timestamp() - rfc3339) MOD rot_X )
  else
    ' rfc3339 in the future
    id = rfc3339
  fi
else
  ' no rfc3339 input, use timestamp()
  rfc3339 = timestamp()
  id = rfc3339
fi
rotation_rfc3339 = id + rot_X

[pkeecom]

Why has this issue has not been fixed since Jun 28, 2021? How else can one create a rotating timestamp starting say 15 days from now to rotate every 30 days?

rfc3339 should be the base timestamp. It should only be used to start the rotation from.

[faultymonk]

BTW, I also ran into this bug...

The workaround requires that the rfc3339 is not defined and for the time_rotating when defining the resource. Instead seed the resource with the desired time via import.

Example command to obtain timestamps:

• gdate -u +%Y-%m-%dT%H:%M:%SZ - current time
• gdate -u +%Y-%m-%dT%H:%M:%SZ --date="+12 hours" - 12 hours in the future

Example import command 12 hours in the future w/ daily rotation:

terraform import time_rotating.example_daily "$(gdate -u +%Y-%m-%dT%H:%M:%SZ --date="+12 hours"),,,1,,"

Looks like #180 would resolve this issue.

[SBGoods]

Hi @m273d15 thanks for raising this issue,
fixing this issue requires a significant rewrite in the resource's logic and will result in a breaking change for practitioners. We will consider this issue as part of a larger effort for a Time Provider major release in the future but we do not have a timeline for this at the moment.

[Mike-Nahmias]

I think another workaround is to only set rfc3339 on creation and then leave it null going forward. Seemed to work for me:

resource "time_static" "first_run_timestamp" {
  rfc3339 = plantimestamp()

  lifecycle {
    ignore_changes = [ rfc3339 ]
  }
}


resource "time_rotating" "test" {
  rfc3339 = time_static.first_run_timestamp.rfc3339 == plantimestamp() ? timeadd(plantimestamp(), "-5m") : null
  rotation_minutes = 10
}

Unfortunately time_static seems to have similar issues where when you set rfc3339 it will perpetually recreate it, which is why I ignore that attribute after creation.

[james-woodbridge]

Just commenting to say I found this after encountering the same issue those have described above - this resource is pointless if it doesn't maintain a constantly rotating time. At the moment, after the rotation period has elapsed the resource behaves like timestamp()!