terraform

Commit Graph

Author	SHA1	Message	Date
Alisdair McDiarmid	b335918c3c	backend: Only show root module output changes When rendering planned output changes, we need to filter the plan's output changes to ensure that only root module outputs which have changed are rendered. Otherwise we will render changes for submodule outputs, and (with concise diff disabled) render unchanged outputs also.	6 years ago
Martin Atkins	31a4b44d2e	backend/local: treat output changes as side-effects to be applied This is a baby-step towards an intended future where all Terraform actions which have side-effects in either remote objects or the Terraform state can go through the plan+apply workflow. This initial change is focused only on allowing plan+apply for changes to root module output values, so that these can be written into a new state snapshot (for consumption by terraform_remote_state elsewhere) without having to go outside of the primary workflow by running "terraform refresh". This is also better than "terraform refresh" because it gives an opportunity to review the proposed changes before applying them, as we're accustomed to with resource changes. The downside here is that Terraform Core was not designed to produce accurate changesets for root module outputs. Although we added a place for it in the plan model in Terraform 0.12, Terraform Core currently produces inaccurate changesets there which don't properly track the prior values. We're planning to rework Terraform Core's evaluation approach in a forthcoming release so it would itself be able to distinguish between the prior state and the planned new state to produce an accurate changeset, but this commit introduces a temporary stop-gap solution of implementing the logic up in the local backend code, where we can freeze a snapshot of the prior state before we take any other actions and then use that to produce an accurate output changeset to decide whether the plan has externally-visible side-effects and render any changes to output values. This temporary approach should be replaced by a more appropriately-placed solution in Terraform Core in a release, which should then allow further behaviors in similar vein, such as user-visible drift detection for resource instances.	6 years ago

Author

SHA1

Message

Date

Alisdair McDiarmid

b335918c3c

backend: Only show root module output changes

When rendering planned output changes, we need to filter the plan's
output changes to ensure that only root module outputs which have
changed are rendered. Otherwise we will render changes for submodule
outputs, and (with concise diff disabled) render unchanged outputs also.

Martin Atkins

31a4b44d2e

backend/local: treat output changes as side-effects to be applied

This is a baby-step towards an intended future where all Terraform actions
which have side-effects in either remote objects or the Terraform state
can go through the plan+apply workflow.

This initial change is focused only on allowing plan+apply for changes to
root module output values, so that these can be written into a new state
snapshot (for consumption by terraform_remote_state elsewhere) without
having to go outside of the primary workflow by running
"terraform refresh".

This is also better than "terraform refresh" because it gives an
opportunity to review the proposed changes before applying them, as we're
accustomed to with resource changes.

The downside here is that Terraform Core was not designed to produce
accurate changesets for root module outputs. Although we added a place for
it in the plan model in Terraform 0.12, Terraform Core currently produces
inaccurate changesets there which don't properly track the prior values.

We're planning to rework Terraform Core's evaluation approach in a
forthcoming release so it would itself be able to distinguish between the
prior state and the planned new state to produce an accurate changeset,
but this commit introduces a temporary stop-gap solution of implementing
the logic up in the local backend code, where we can freeze a snapshot of
the prior state before we take any other actions and then use that to
produce an accurate output changeset to decide whether the plan has
externally-visible side-effects and render any changes to output values.

This temporary approach should be replaced by a more appropriately-placed
solution in Terraform Core in a release, which should then allow further
behaviors in similar vein, such as user-visible drift detection for
resource instances.

2 Commits (25cebfbd8be2c43a25dfafdcf882e79b9ccc3d3d)