Saved plan fails to apply when datasource depends on resource

[alkar]

Terraform Version

v0.9.11

Terraform Configuration Files

resource "random_id" "x" {
  byte_length = 1
}

data "ignition_file" "x" {
  filesystem = "root"
  path       = "/x"

  content {
    content = "${random_id.x.hex}"
  }
}

data "ignition_systemd_unit" "x" {
  name    = "x.service"
  content = ""
}

data "ignition_config" "x" {
  files   = ["${data.ignition_file.x.id}"]
  systemd = ["${data.ignition_systemd_unit.x.id}"]
}

Expected Behavior

It should be able to apply from a saved plan.

Steps to Reproduce

Applying directly works:

$ terraform apply
data.ignition_systemd_unit.x: Refreshing state...
random_id.x: Creating...
  b64:         "" => "<computed>"
  b64_std:     "" => "<computed>"
  b64_url:     "" => "<computed>"
  byte_length: "" => "1"
  dec:         "" => "<computed>"
  hex:         "" => "<computed>"
random_id.x: Creation complete (ID: dg)
data.ignition_file.x: Refreshing state...
data.ignition_config.x: Refreshing state...

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

The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.

State path:

However, applying from a saved plan file:

$ terraform plan -out sp && terraform apply sp
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

data.ignition_systemd_unit.x: Refreshing state...
The Terraform execution plan has been generated and is shown below.
Resources are shown in alphabetical order for quick scanning. Green resources
will be created (or destroyed and then created if an existing resource
exists), yellow resources are being changed in-place, and red resources
will be destroyed. Cyan entries are data sources to be read.

Your plan was also saved to the path below. Call the "apply" subcommand
with this plan file and Terraform will exactly execute this execution
plan.

Path: sp

<= data.ignition_config.x
    files.#:   "<computed>"
    rendered:  "<computed>"
    systemd.#: "1"
    systemd.0: "c3582dce636f921cdc80f72fd27057f1fd14bd0b2a656383e2da0de1b09d3d2c"

<= data.ignition_file.x
    content.#:         "1"
    content.0.content: "${random_id.x.hex}"
    content.0.mime:    "text/plain"
    filesystem:        "root"
    path:              "/x"

+ random_id.x
    b64:         "<computed>"
    b64_std:     "<computed>"
    b64_url:     "<computed>"
    byte_length: "1"
    dec:         "<computed>"
    hex:         "<computed>"


Plan: 1 to add, 0 to change, 0 to destroy.
random_id.x: Creating...
  b64:         "" => "<computed>"
  b64_std:     "" => "<computed>"
  b64_url:     "" => "<computed>"
  byte_length: "" => "1"
  dec:         "" => "<computed>"
  hex:         "" => "<computed>"
random_id.x: Creation complete (ID: Qg)
data.ignition_file.x: Refreshing state...
data.ignition_config.x: Refreshing state...
Error applying plan:

1 error(s) occurred:

* data.ignition_config.x: data.ignition_config.x: invalid systemd unit "c3582dce636f921cdc80f72fd27057f1fd14bd0b2a656383e2da0de1b09d3d2c", unknown systemd unit id

Terraform does not automatically rollback in the face of errors.
Instead, your Terraform state file has been partially updated with
any resources that successfully completed. Please address the error
above and apply again to incrementally change your infrastructure.

$ terraform apply sp
Failed to load backend: This plan was created against an older state than is current. Please create
a new plan file against the latest state and try again.

Terraform doesn't allow you to run plans that were created from older
states since it doesn't properly represent the latest changes Terraform
may have made, and can result in unsafe behavior.

Plan Serial:    0
Current Serial: 1

$ terraform plan -out sp && terraform apply sp
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

random_id.x: Refreshing state... (ID: Qg)
data.ignition_systemd_unit.x: Refreshing state...
data.ignition_file.x: Refreshing state...
data.ignition_config.x: Refreshing state...
No changes. Infrastructure is up-to-date.

This means that Terraform did not detect any differences between your
configuration and real physical resources that exist. As a result, Terraform
doesn't need to do anything.

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

References

Possibly #11518

[alkar]

After the apply failure, if you look at the "intermediate" state file, the systemd unit that is supposedly invalid is actually in there.

[apparentlymart]

Hi @alkar! Sorry for this strange behavior.

I'm going to have our bot move this issue over to the ignition provider repository, since there are more people familiar with ignition watching issues there. (This should happen at some point in the next hour or so.)

[hashibot]

This issue has been automatically migrated to hashicorp/terraform-provider-ignition#12 because it looks like an issue with that provider. If you believe this is not an issue with the provider, please reply to this issue and let us know.

[alkar]

Thanks @apparentlymart. I thought it might be related to how terraform handles datasources at the refresh stage so that's why I raised it on the main repo. I'll follow up on the new ticket.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.