Guards

Conditional task execution using When() predicates and OnlyIfChanged().

When

When takes a predicate that receives completed task results. The task only runs if the predicate returns true.

summary := plan.TaskFunc("print-summary",
    func(_ context.Context, _ *client.Client) (*orchestrator.Result, error) {
        return &orchestrator.Result{Changed: false}, nil
    },
)
summary.DependsOn(getHostname)
summary.When(func(results orchestrator.Results) bool {
    r := results.Get("get-hostname")
    return r != nil && r.Status == orchestrator.StatusChanged
})

WhenWithReason

WhenWithReason works like When but provides a custom skip reason that is passed to the OnSkip hook when the guard returns false.

deploy.WhenWithReason(
    func(results orchestrator.Results) bool {
        r := results.Get("check-config")
        return r != nil && r.Status == orchestrator.StatusChanged
    },
    "config unchanged, skipping deploy",
)

Without a reason, skipped tasks report a generic message. Use WhenWithReason when you want descriptive skip output in your hooks.

OnlyIfChanged

OnlyIfChanged skips the task unless at least one dependency reported a change. See Only If Changed for details.

logChange := plan.TaskFunc("log-change",
    func(_ context.Context, _ *client.Client) (*orchestrator.Result, error) {
        return &orchestrator.Result{Changed: true}, nil
    },
)
logChange.DependsOn(deploy)
logChange.OnlyIfChanged()

Example

See examples/sdk/orchestrator/features/guards.go for a complete working example.