Previously we had three different layers all thinking they were
responsible for substituting a default value for an unset root module
variable:
- the local backend, via logic in backend.ParseVariableValues
- the context.Plan function (and other similar functions) trying to
preprocess the input variables using
terraform.mergeDefaultInputVariableValues .
- the newer prepareFinalInputVariableValue, which aims to centralize all
of the variable preparation logic so it can be common to both root and
child module variables.
The second of these was also trying to handle type constraint checking,
which is also the responsibility of the central function and not something
we need to handle so early.
Only the last of these consistently handles both root and child module
variables, and so is the one we ought to keep. The others are now
redundant and are causing prepareFinalInputVariableValue to get a slightly
corrupted view of the caller's chosen variable values.
To rectify that, here we remove the two redundant layers altogether and
have unset root variables pass through as cty.NilVal all the way to the
central prepareFinalInputVariableValue function, which will then handle
them in a suitable way which properly respects the "nullable" setting.
This commit includes some test changes in the terraform package to make
those tests no longer rely on the mergeDefaultInputVariableValues logic
we've removed, and to instead explicitly set cty.NilVal for all unset
variables to comply with our intended contract for PlanOpts.SetVariables,
and similar. (This is so that we can more easily catch bugs in callers
where they _don't_ correctly handle input variables; it allows us to
distinguish between the caller explicitly marking a variable as unset vs.
not describing it at all, where the latter is a bug in the caller.)
1. ParseDeclaredValues: parses unparsed variables into terraform.InputValues
2. ProbeUndeclaredVariableValues: compares variable declarations with unparsed values to warn/error about undeclared variables
In order to handle optional attributes, the Variable type needs to keep
track of the type constraint for decoding and conversion, as well as the
concrete type for creating values and type comparison.
Since the Type field is referenced throughout the codebase, and for
future refactoring if the handling of optional attributes changes
significantly, the constraint is now loaded into an entirely new field
called ConstraintType. This prevents types containing
ObjectWithOptionalAttrs from escaping the decode/conversion codepaths
into the rest of the codebase.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
Martin Atkins