Credential prompting¶

Package github.com/sylvanld/go-flexconf/flexprompt collects input values — typically credentials — from wherever your program runs: an interactive terminal, CI environment variables, or canned values in tests. Components that need input declare what they need; the single installed Prompter answers everything in one interaction.

Normative spec: prompter.md.

Quick start¶

import "github.com/sylvanld/go-flexconf/flexprompt"

func main() {
    // Interactive apps opt in once at startup:
    flexprompt.SetPrompter(flexprompt.NewCLIPrompter())
    // …
}

If no prompter is installed, GetPrompter() returns a safe default whose Dispatch fails every required request with ErrNoPrompter — a daemon never hangs reading stdin by accident.

The `Prompter` interface¶

type Prompter interface {
    Dispatch(ctx context.Context, reqs []PromptRequest) (map[string]string, error)
}

Dispatch answers all requests in a single interaction and returns the answers keyed by PromptRequest.ID:

An optional request with no value is omitted from the result.
A required request with no value fails with ErrPromptUnavailable.
On any non-nil error the returned map is nil — never read it.
Duplicate or empty request IDs are programming errors and fail loudly.

`PromptRequest`¶

Field	Meaning
`ID`	Stable machine key (`"password"`). The join key between declaration and answers; non-interactive prompters use it as the lookup key.
`Label`	Human-facing text for interactive prompters.
`Secret`	Masked input; never echoed or logged.
`Optional`	Value may be absent (omitted from answers).
`Default`	Suggested value for interactive prompters. Ignored when `Secret` is true.
`Confirm`	Interactive double-entry (new passwords); entries must match. Ignored by non-interactive prompters.

The process-wide singleton¶

func SetPrompter(p Prompter) // install once at startup; nil resets to default
func GetPrompter() Prompter  // never nil; default fails required requests with ErrNoPrompter

Prompting is a process-level concern (where am I running?), so there is exactly one prompter, not one per vault. Both accessors are safe for concurrent use. SetPrompter(nil) restores the default — handy between tests.

Built-in prompters¶

Constructor	Use case	Behaviour
`NewCLIPrompter(opts...)`	interactive terminal	Asks each request in turn; masks `Secret` input (via `x/term`); honours `Default` and `Confirm`.
`NewMapPrompter(values)`	tests, presets	Resolves each `ID` from the map.
`NewEnvPrompter(prefix)`	CI	Resolves `ID` from `prefix + ID` uppercased, dashes → underscores (`FLEXCONF_` + `keyfile-passphrase` → `FLEXCONF_KEYFILE_PASSPHRASE`).
`PrompterFunc(fn)`	adapters	Wraps a function as a `Prompter`.

NewCLIPrompter accepts WithCLIStreams(in *os.File, out io.Writer) to redirect its terminal streams (defaults os.Stdin / os.Stderr).

Errors¶

var (
    ErrPromptCancelled   error // user aborted; terminal — callers stop retrying
    ErrPromptUnavailable error // required request unresolved (non-interactive)
    ErrNoPrompter        error // no prompter installed; call SetPrompter
)

Match with errors.Is; messages are not part of the contract.