terraform

Commit Graph

Author	SHA1	Message	Date
Martin Atkins	88e76fa9ef	configs/configschema: Introduce the NestingGroup mode for blocks In study of existing providers we've found a pattern we werent previously accounting for of using a nested block type to represent a group of arguments that relate to a particular feature that is always enabled but where it improves configuration readability to group all of its settings together in a nested block. The existing NestingSingle was not a good fit for this because it is designed under the assumption that the presence or absence of the block has some significance in enabling or disabling the relevant feature, and so for these always-active cases we'd generate a misleading plan where the settings for the feature appear totally absent, rather than showing the default values that will be selected. NestingGroup is, therefore, a slight variation of NestingSingle where presence vs. absence of the block is not distinguishable (it's never null) and instead its contents are treated as unset when the block is absent. This then in turn causes any default values associated with the nested arguments to be honored and displayed in the plan whenever the block is not explicitly configured. The current SDK cannot activate this mode, but that's okay because its "legacy type system" opt-out flag allows it to force a block to be processed in this way anyway. We're adding this now so that we can introduce the feature in a future SDK without causing a breaking change to the protocol, since the set of possible block nesting modes is not extensible.	7 years ago
Martin Atkins	bbbf22d8e4	configs/configschema: Block.StaticValidateTraversal method This allows basic static validation of a traversal against a schema, to verify that it represents a valid path through the structural parts of the schema. The main purpose of this is to produce better error messages (using our knowledge of the schema) than we'd be able to achieve by just relying on HCL expression evaluation errors. This is particularly important for nested blocks because it may not be obvious whether one is represented internally by a set or a list, and incorrect usage would otherwise produce a confusing HCL-oriented error message.	8 years ago

Author

SHA1

Message

Date

Martin Atkins

88e76fa9ef

configs/configschema: Introduce the NestingGroup mode for blocks

In study of existing providers we've found a pattern we werent previously
accounting for of using a nested block type to represent a group of
arguments that relate to a particular feature that is always enabled but
where it improves configuration readability to group all of its settings
together in a nested block.

The existing NestingSingle was not a good fit for this because it is
designed under the assumption that the presence or absence of the block
has some significance in enabling or disabling the relevant feature, and
so for these always-active cases we'd generate a misleading plan where
the settings for the feature appear totally absent, rather than showing
the default values that will be selected.

NestingGroup is, therefore, a slight variation of NestingSingle where
presence vs. absence of the block is not distinguishable (it's never null)
and instead its contents are treated as unset when the block is absent.
This then in turn causes any default values associated with the nested
arguments to be honored and displayed in the plan whenever the block is
not explicitly configured.

The current SDK cannot activate this mode, but that's okay because its
"legacy type system" opt-out flag allows it to force a block to be
processed in this way anyway. We're adding this now so that we can
introduce the feature in a future SDK without causing a breaking change
to the protocol, since the set of possible block nesting modes is not
extensible.

Martin Atkins

bbbf22d8e4

configs/configschema: Block.StaticValidateTraversal method

This allows basic static validation of a traversal against a schema, to
verify that it represents a valid path through the structural parts of
the schema.

The main purpose of this is to produce better error messages (using our
knowledge of the schema) than we'd be able to achieve by just relying
on HCL expression evaluation errors. This is particularly important for
nested blocks because it may not be obvious whether one is represented
internally by a set or a list, and incorrect usage would otherwise produce
a confusing HCL-oriented error message.

2 Commits (e8ee3f14a4ffcc5df888b2ec2b4e3bec1162dce7)