preflight

type Check struct {
	// Kind is what was checked: repository, paths, image, host or infrastructure.
	Kind string `json:"kind"`
	// Target names it, without credentials.
	Target string `json:"target"`
	Status Status `json:"status"`
	// Detail is the result in words: what resolved, or why it failed or was not checked.
	Detail string `json:"detail"`
}

type Options struct {
	// Offline skips every check that needs the network, and reports each as not checked.
	Offline bool
	// Timeout bounds each target's checks. Zero means 20 seconds.
	Timeout time.Duration
	// Concurrency bounds how many targets are checked at once. Zero means 8.
	Concurrency int
	Probes      Probes
}

type Probes struct {
	// Revision resolves a repository's revision to a commit.
	Revision func(ctx context.Context, url, revision string) (string, error)
	// Paths checks a repository's paths at a revision and returns the commit it read.
	Paths func(ctx context.Context, url, revision string, paths []string) (string, error)
	// Image checks that an image can be read, and says from where.
	Image func(ctx context.Context, ref string, offline bool) (string, error)
	// Host opens a connection to an endpoint and says what it established.
	Host func(ctx context.Context, rawURL string) (string, error)
}

type Status string