Files
dnswatcher/internal/healthcheck/healthcheck.go
T
clawbot 774f7caff6
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healthcheck: answer 503 when no root server gave a usable reply in the last round of DNS checks (closes #302)
The health check answered ok while every DNS lookup failed, as on a
network that intercepts DNS queries. A lookup whose root servers give no
usable reply now fails with ErrNoRootServerAnswered. At the end of each
round of DNS checks that shutdown did not cut short, the watcher records
whether every lookup failed with it or with ErrIntercepted; the health
check then gives status error, and /.well-known/healthcheck and /health
answer 503. Until the first round finishes it stays ok.

The health check now depends on the watcher, so fx starts the watcher
before the HTTP server and stops the server first. NewWithRootServers
lets tests start a resolver's walks at real servers that are not root
servers.

Model: opus-5-5
2026-10-18 17:24:49 +02:00

95 lines
2.2 KiB
Go

// Package healthcheck provides application health status.
package healthcheck
import (
"context"
"log/slog"
"time"
"go.uber.org/fx"
"sneak.berlin/go/dnswatcher/internal/config"
"sneak.berlin/go/dnswatcher/internal/globals"
"sneak.berlin/go/dnswatcher/internal/logger"
"sneak.berlin/go/dnswatcher/internal/watcher"
)
// Values of Response.Status.
const (
StatusOK = "ok"
StatusError = "error"
)
// Params contains dependencies for Healthcheck.
type Params struct {
fx.In
Globals *globals.Globals
Config *config.Config
Logger *logger.Logger
Watcher *watcher.Watcher
}
// Healthcheck provides health status information.
type Healthcheck struct {
StartupTime time.Time
log *slog.Logger
params *Params
}
// Response is the health check response structure.
type Response struct {
Status string `json:"status"`
Now string `json:"now"`
UptimeSeconds int64 `json:"uptimeSeconds"`
UptimeHuman string `json:"uptimeHuman"`
Version string `json:"version"`
Appname string `json:"appname"`
Maintenance bool `json:"maintenanceMode"`
}
// New creates a new Healthcheck instance.
func New(
lifecycle fx.Lifecycle,
params Params,
) (*Healthcheck, error) {
healthcheck := &Healthcheck{
log: params.Logger.Get(),
params: &params,
}
lifecycle.Append(fx.Hook{
OnStart: func(_ context.Context) error {
healthcheck.StartupTime = time.Now()
return nil
},
})
return healthcheck, nil
}
// Check returns the current health status. Status is StatusError when
// the watcher's most recent round of DNS checks could not reach the DNS
// (see watcher.Watcher.DNSUnreachable), and StatusOK otherwise.
func (h *Healthcheck) Check() *Response {
status := StatusOK
if h.params.Watcher.DNSUnreachable() {
status = StatusError
}
return &Response{
Status: status,
Now: time.Now().UTC().Format(time.RFC3339Nano),
UptimeSeconds: int64(h.uptime().Seconds()),
UptimeHuman: h.uptime().String(),
Appname: h.params.Globals.Appname,
Version: h.params.Globals.Version,
Maintenance: h.params.Config.MaintenanceMode,
}
}
func (h *Healthcheck) uptime() time.Duration {
return time.Since(h.StartupTime)
}