conditional

pkg/provisioners/conditional

Intention

pkg/provisioners/conditional is a small provisioner combinator for optional subordinate resources. It gates a child provisioner behind a predicate, but the key behavior is stronger than simple skipping: when the predicate is false, the child is actively deprovisioned.

This makes the package useful for feature- or capability-dependent child provisioners where the desired state is binary:

• predicate true: the child should exist
• predicate false: the child should not exist

Invariants And Guard Rails

• Provision(ctx) does not mean "try to provision if enabled and otherwise do nothing". It means "drive the child to the desired existence state for the current predicate value."
• If the predicate is true, Provision(ctx) delegates to the child provisioner's Provision(ctx).
• If the predicate is false, Provision(ctx) delegates to the child provisioner's Deprovision(ctx).
• Deprovision(ctx) always delegates to the child provisioner's Deprovision(ctx), regardless of predicate value, so cleanup still happens during parent teardown even when the child was conditionally disabled.
• This combinator is appropriate when predicate false really means the child resource must not exist.

Caveats

• The predicate is just func() bool. It carries no context, error handling, or structured explanation of why the child is enabled or disabled.
• This package encodes removal semantics, not skip semantics. If a caller wants "disabled for now, but preserve existing child state," this is the wrong abstraction.
• Because false maps to deprovision, callers must be deliberate about using predicates that can flap.
• The package is intentionally tiny and does not add lifecycle policy beyond delegating to the child provisioner based on the predicate.