Documentation
¶
Overview ¶
Package render plugs FastConf into the long tail of legacy daemons that only consume on-disk configuration files (nginx.conf, envoy.yaml, postgresql.conf, ...). It mirrors the Consul-Template / Spring Cloud Config "render to disk + signal" workflow but stays inside the calling Go process, so there is no separate sidecar to operate.
A Wire[T] call subscribes to a Manager's per-T notifications, renders the typed snapshot through a Renderer, atomically writes the bytes to outPath via a temp-file + rename(2), and finally fires every registered OnChange hook (SIGHUP a pid, POST to a webhook, restart a systemd unit, ...). On any error the previous file is preserved and a structured log line is emitted; the framework never partially overwrites the destination.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Wire ¶
func Wire[T any]( mgr *fastconf.Manager[T], r Renderer[T], outPath string, opts Options, hooks ...Hook, ) (cancel func(), err error)
Wire subscribes to mgr's typed snapshot stream, atomically writes the rendered bytes to outPath, then runs every hook in order. The returned cancel removes the subscription; the renderer fires once eagerly for the current snapshot so the file exists before the function returns.
Types ¶
type Hook ¶
Hook runs after a successful atomic write. Hooks should be fast and non-fatal; an error is logged but does not roll back the write.
func HTTPGet ¶
HTTPGet returns a Hook that issues a GET to url and treats any 2xx/3xx response as success. Use it to poke a webhook or kick off an external orchestrator after every config change.
func ReloadSystemd ¶
ReloadSystemd returns a Hook that runs `systemctl reload <unit>`. It is implemented via os/exec rather than the dbus binding to keep this module dependency-free; mocked in tests via Options.OnError verification.
type Options ¶
type Options struct {
// FileMode for the rendered file (default 0o644).
FileMode os.FileMode
// HookTimeout caps each hook invocation (default 5s).
HookTimeout time.Duration
// OnError, when non-nil, receives every render/write/hook failure
// in addition to the slog logger (the manager's default).
OnError func(err error)
// SkipFirstHook, when true, writes the file once on Wire() but does
// NOT fire hooks for that initial render. Use when downstream
// daemons are not yet up at boot and a SIGHUP would race with their
// own startup. Phase 20 BUG-203.
SkipFirstHook bool
}
Options configures Wire. The zero value is valid: temp files are created next to the destination, the hook context defaults to context.Background(), and write mode falls back to 0o644.
type Renderer ¶
Renderer turns a strongly-typed configuration snapshot into bytes. The most common impl is GoTemplate; users can supply their own (e.g. a pongo2 or jet renderer) without depending on this module's templating.
func GoTemplate ¶
GoTemplate returns a Renderer that loads the named text/template file once and re-executes it on every snapshot. The template's data is the dereferenced *T (so users write `{{ .Server.Port }}`), and FuncMap can inject helpers (e.g. quote, indent). Pass nil FuncMap for the defaults.
type RendererFunc ¶
RendererFunc adapts a free function to the Renderer interface.
func (RendererFunc[T]) Render ¶
func (f RendererFunc[T]) Render(v *T) ([]byte, error)
Render implements Renderer.
Source Files