clientlifecycle¶

Build an expensive thing once, share it, and never cache the failure.

clientlifecycle holds one small state machine: the rule for turning a Builder[T] — anything expensive and failure-prone, typically a credential resolution — into a Resolver[T] that concurrent callers can share safely.

It exists because that rule was being written repeatedly across the estate, each copy subtly different and each one tested from scratch. It is written once here, raced once here, and depended on everywhere.

src := clientlifecycle.Memoised(func(ctx context.Context) (aws.Config, error) {
    return config.LoadDefaultConfig(ctx)
})

cfg, err := src.Get(ctx)   // first call resolves; the rest share the result

It costs nothing to depend on¶

This module has no third-party dependencies at all — not few, none. A test asserts it rather than leaving it to review, because every provider client module in the estate depends on this one, so anything arriving here is inherited everywhere.

Three strategies, and the choice is yours¶

Strategy	Holds the value	Take it when
`Memoised`	forever	the value refreshes itself, and you are content to hold it
`PerCall`	never	you decline to hold a credential longer than an operation needs
`Invalidatable`	until told otherwise	the value cannot renew itself, and building it is expensive

Which one to take is a property of your posture and your provider, not something this package decides for you. Choosing a strategy walks the three questions that settle it.

Start here¶

Getting started — build your first resolver, and see the failure behaviour that makes it different from sync.OnceValues.
Choose a strategy — the three questions.
Invalidate a stale credential — and the signal you must not invalidate on.
Why a failure is never cached — the decision the whole module is built around.
The generation model — how invalidation stays correct while an attempt is already running.

Where this comes from¶

The state machine is decision D-4 of org spec 0002; this module is P-4 of org spec 0003, and the invalidatable strategy is P-16.