Retry validator-agent/prober registration; show validator hostname

Both binaries registered with control-api exactly once at startup and
exited (os.Exit(1)) on any failure — including control-api simply not
being up yet (no ordering guarantee between the two at boot/redeploy) or
the admin not having added this validator_id/site_id to the config yet.
Run() now retries registration with capped exponential backoff (3s->30s)
until it succeeds or the process is asked to shut down, instead of
crashing; registerWithRetry is identical in agentcore and probercore
since their Run/register shape already was.

Separately, the admin dashboard's Validators page had no hostname column
even though the agent already reports one on register (mirroring the
prober) and control-api already persists it — only the admin-config read
DTO (validatorDTO in httpapi and dashboard) dropped it before it reached
the template. Added hostname + last_heartbeat_at to that DTO end-to-end
and a Хост/Heartbeat column to validators.html, matching sites.html.

Rebuilt bin/{control-api,admin-dashboard,prober,validator-agent} and
bin/SHA256SUMS per docs/SETUP.md's documented build recipe.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

bin/SHA256SUMS

@@ -1,4 +1,4 @@
-8f2ad37b7819131a9b25eee9d35a57880c7aa233bbb741f4fd8dc0af33f6241c  control-api
-3288930ce4e09e6793048103e25991f025f71dbedced39dee9bccf821eb72a3d  validator-agent
-586cb533631dfcef2246cdb69e20777f882506755d15afe475399356c1ed2d02  prober
-4729c33a2bce584cba29a8833b0701c0a1cd98bb17bf331aabffc27c4cde940c  admin-dashboard
+dcb137ae6a3f6a59465f2772215d48f98fd303dd1c266645b20ec70194ab7915  control-api
+b7a6068db1d095ae7b73cbd9b7273d6a1629ae017e9c3c9601e103432894a247  validator-agent
+be8e9576c6fbe5e5798b5d4b758a5617b63bea6abe80e326998d10583edbbf5c  prober
+579253ac22d6b9537870cf45aaa85437a4a9dba0c87eab9ba8c49c28e50ee438  admin-dashboard

internal/agentcore/agentcore.go

@@ -30,6 +30,13 @@ type Agent struct {
 	log    *slog.Logger
 
 	lastHandledIPID int64
+
+	// registerRetryInitial/Max govern the backoff used while waiting for a
+	// successful registration (see registerWithRetry): control-api may not
+	// be up yet at agent boot, or may come and go across a redeploy, and the
+	// agent should keep waiting rather than exit.
+	registerRetryInitial time.Duration
+	registerRetryMax     time.Duration
 }
 
 func New(cfg *config.ValidatorAgent, log *slog.Logger) *Agent {
@@ -38,17 +45,19 @@ func New(cfg *config.ValidatorAgent, log *slog.Logger) *Agent {
 		timeout = 10 * time.Second
 	}
 	return &Agent{
-		cfg:    cfg,
-		client: apiclient.New(cfg.ControlAPIURL, timeout+5*time.Second),
-		log:    log,
+		cfg:                  cfg,
+		client:               apiclient.New(cfg.ControlAPIURL, timeout+5*time.Second),
+		log:                  log,
+		registerRetryInitial: 3 * time.Second,
+		registerRetryMax:     30 * time.Second,
 	}
 }
 
 // Run registers with the Control API and polls forever until ctx is
 // cancelled.
 func (a *Agent) Run(ctx context.Context) error {
-	if err := a.register(ctx); err != nil {
-		return fmt.Errorf("register: %w", err)
+	if err := a.registerWithRetry(ctx); err != nil {
+		return err
 	}
 
 	interval := time.Duration(a.cfg.PollIntervalSeconds) * time.Second
@@ -88,6 +97,32 @@ func (a *Agent) register(ctx context.Context) error {
 	return nil
 }
 
+// registerWithRetry retries register with capped exponential backoff until
+// it succeeds or ctx is cancelled. Control-api may not be reachable yet at
+// agent boot (started before control-api, or a network blip), or may reject
+// the request until an admin adds this validator_id to its config — either
+// way the agent should keep waiting rather than exit, since both conditions
+// can resolve on their own after the agent has already started.
+func (a *Agent) registerWithRetry(ctx context.Context) error {
+	delay := a.registerRetryInitial
+	for {
+		err := a.register(ctx)
+		if err == nil {
+			return nil
+		}
+		a.log.Warn("registration failed, will retry", "err", err, "retry_in", delay)
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-time.After(delay):
+		}
+		delay *= 2
+		if delay > a.registerRetryMax {
+			delay = a.registerRetryMax
+		}
+	}
+}
+
 type heartbeatReq struct {
 	LocalState string `json:"local_state"`
 }

internal/agentcore/agentcore_test.go

@@ -0,0 +1,100 @@
+package agentcore
+
+import (
+	"context"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"cloudipvalidator/internal/apiclient"
+	"cloudipvalidator/internal/config"
+)
+
+func testLogger() *slog.Logger {
+	return slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
+}
+
+// TestRegisterWithRetrySucceedsAfterControlAPIComesUp mirrors starting the
+// validator-agent before control-api is up (or before an admin has
+// configured this validator_id): the first attempts fail, and the agent
+// must keep retrying — not give up — until registration succeeds.
+func TestRegisterWithRetrySucceedsAfterControlAPIComesUp(t *testing.T) {
+	var attempts int32
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /api/v1/agents/register", func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&attempts, 1)
+		if n < 3 {
+			w.WriteHeader(http.StatusServiceUnavailable)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"ok":true,"poll_interval_seconds":5}`))
+	})
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	a := &Agent{
+		cfg:                  &config.ValidatorAgent{ValidatorID: "val-1", ControlAPIURL: ts.URL},
+		client:               apiclient.New(ts.URL, 5*time.Second),
+		log:                  testLogger(),
+		registerRetryInitial: time.Millisecond,
+		registerRetryMax:     5 * time.Millisecond,
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	if err := a.registerWithRetry(ctx); err != nil {
+		t.Fatalf("expected eventual success, got err: %v", err)
+	}
+	if got := atomic.LoadInt32(&attempts); got != 3 {
+		t.Fatalf("expected exactly 3 attempts, got %d", got)
+	}
+}
+
+// TestRegisterWithRetryStopsOnCancel confirms a validator-agent waiting on
+// an unreachable/unconfigured control-api can still be shut down promptly
+// (e.g. via SIGTERM) instead of retrying forever with no way out.
+func TestRegisterWithRetryStopsOnCancel(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /api/v1/agents/register", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusBadRequest)
+	})
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	a := &Agent{
+		cfg:                  &config.ValidatorAgent{ValidatorID: "val-1", ControlAPIURL: ts.URL},
+		client:               apiclient.New(ts.URL, 5*time.Second),
+		log:                  testLogger(),
+		registerRetryInitial: 10 * time.Millisecond,
+		registerRetryMax:     10 * time.Millisecond,
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		time.Sleep(30 * time.Millisecond)
+		cancel()
+	}()
+
+	var err error
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		err = a.registerWithRetry(ctx)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("registerWithRetry did not return after ctx cancellation")
+	}
+	if err != context.Canceled {
+		t.Fatalf("expected context.Canceled, got %v", err)
+	}
+}

internal/dashboard/dto.go

@@ -97,9 +97,11 @@ type clearQueueResponse struct {
 }
 
 type validatorDTO struct {
-	ValidatorID string `json:"validator_id"`
-	OSPortID    string `json:"os_port_id"`
-	State       string `json:"state"`
+	ValidatorID     string     `json:"validator_id"`
+	Hostname        string     `json:"hostname"`
+	OSPortID        string     `json:"os_port_id"`
+	State           string     `json:"state"`
+	LastHeartbeatAt *time.Time `json:"last_heartbeat_at"`
 }
 
 type siteDTO struct {

internal/dashboard/handlers_test.go

@@ -376,6 +376,17 @@ func TestSitesPageShowsProberBadge(t *testing.T) {
 	}
 }
 
+func TestValidatorsPageShowsHostname(t *testing.T) {
+	fake, caURL := newFakeControlAPI(t)
+	fake.validators = append(fake.validators, validatorDTO{ValidatorID: "val-1", Hostname: "validator-host-1", OSPortID: "port-1", State: "idle"})
+	ts := newTestServer(t, caURL)
+
+	page := get(t, ts, "/validators")
+	if !strings.Contains(page, "validator-host-1") {
+		t.Fatalf("expected hostname shown, got:\n%s", page)
+	}
+}
+
 func TestTargetsAndCheckTypesRoundTrip(t *testing.T) {
 	_, caURL := newFakeControlAPI(t)
 	ts := newTestServer(t, caURL)

internal/dashboard/templates/validators.html

@@ -50,12 +50,13 @@
 <div class="panel">
 <div class="table-scroll">
 <table>
-<thead><tr><th>ID</th><th>OS Port ID</th><th>Состояние</th><th></th></tr></thead>
+<thead><tr><th>ID</th><th>Хост</th><th>OS Port ID</th><th>Состояние</th><th>Heartbeat</th><th></th></tr></thead>
 <tbody>
 {{range .Items}}
 {{$b := validatorBadge .State}}
 <tr>
 <td class="mono" data-label="ID">{{.ValidatorID}}</td>
+<td class="mono" data-label="Хост">{{if .Hostname}}{{.Hostname}}{{else}}—{{end}}</td>
 <td data-label="OS Port ID">
 <form class="inline-form" hx-put="/validators/{{.ValidatorID}}" hx-target="#validators-table-wrap" hx-swap="innerHTML">
 <input type="text" name="os_port_id" value="{{.OSPortID}}">
@@ -63,6 +64,7 @@
 </form>
 </td>
 <td data-label="Состояние"><span class="pill {{$b.Class}}">{{$b.Label}}</span></td>
+<td data-label="Heartbeat">{{fmtTime .LastHeartbeatAt}}</td>
 <td data-label="">
 <div class="actions">
 <button class="btn btn-danger-ghost btn-sm" hx-delete="/validators/{{.ValidatorID}}" hx-target="#validators-table-wrap" hx-swap="innerHTML" hx-confirm="Удалить валидатор {{.ValidatorID}}?">Удалить</button>

internal/httpapi/dto_admin.go

@@ -33,9 +33,11 @@ type clearQueueResponse struct {
 }
 
 type validatorDTO struct {
-	ValidatorID string `json:"validator_id"`
-	OSPortID    string `json:"os_port_id"`
-	State       string `json:"state"`
+	ValidatorID     string     `json:"validator_id"`
+	Hostname        string     `json:"hostname"`
+	OSPortID        string     `json:"os_port_id"`
+	State           string     `json:"state"`
+	LastHeartbeatAt *time.Time `json:"last_heartbeat_at"`
 }
 
 type createValidatorRequest struct {

internal/httpapi/handlers_config.go

@@ -17,7 +17,10 @@ func (s *Server) handleConfigListValidators(w http.ResponseWriter, r *http.Reque
 	}
 	out := make([]validatorDTO, len(validators))
 	for i, v := range validators {
-		out[i] = validatorDTO{ValidatorID: v.ValidatorID, OSPortID: v.OSPortID, State: v.State}
+		out[i] = validatorDTO{
+			ValidatorID: v.ValidatorID, Hostname: v.Hostname, OSPortID: v.OSPortID,
+			State: v.State, LastHeartbeatAt: v.LastHeartbeatAt,
+		}
 	}
 	writeJSON(w, http.StatusOK, out)
 }

internal/httpapi/handlers_config_test.go

@@ -666,6 +666,35 @@ func TestProberRegisterSetsHostnameAndIdleState(t *testing.T) {
 	}
 }
 
+// TestValidatorRegisterSetsHostname proves the admin config listing surfaces
+// a validator's hostname (and heartbeat time) once its agent registers,
+// mirroring TestProberRegisterSetsHostnameAndIdleState for sites.
+func TestValidatorRegisterSetsHostname(t *testing.T) {
+	fc, _, _, _ := newConfigTestHarness(t)
+
+	fc.do(http.MethodPost, "/api/v1/admin/config/validators", createValidatorRequest{ValidatorID: "val-1", OSPortID: "port-1"})
+
+	resp, body := fc.do(http.MethodPost, "/api/v1/agents/register", registerAgentRequest{ValidatorID: "val-1", Hostname: "validator-host-1", AgentVersion: "test"})
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("register agent: status=%d body=%s", resp.StatusCode, body)
+	}
+
+	resp, body = fc.do(http.MethodGet, "/api/v1/admin/config/validators", nil)
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("get validators: status=%d body=%s", resp.StatusCode, body)
+	}
+	var validators []validatorDTO
+	if err := json.Unmarshal(body, &validators); err != nil {
+		t.Fatalf("unmarshal validators: %v", err)
+	}
+	if len(validators) != 1 || validators[0].Hostname != "validator-host-1" {
+		t.Fatalf("expected hostname validator-host-1, got %+v", validators)
+	}
+	if validators[0].LastHeartbeatAt != nil {
+		t.Fatalf("expected no heartbeat yet (only register was called), got %+v", validators[0].LastHeartbeatAt)
+	}
+}
+
 // TestProberHeartbeat404UnknownSite proves the heartbeat endpoint rejects
 // an unconfigured site_id, mirroring the validator heartbeat's 404.
 func TestProberHeartbeat404UnknownSite(t *testing.T) {

internal/probercore/probercore.go

@@ -8,7 +8,6 @@ package probercore
 
 import (
 	"context"
-	"fmt"
 	"log/slog"
 	"os"
 	"time"
@@ -22,6 +21,13 @@ type Prober struct {
 	cfg    *config.Prober
 	client *apiclient.Client
 	log    *slog.Logger
+
+	// registerRetryInitial/Max govern the backoff used while waiting for a
+	// successful registration (see registerWithRetry): control-api may not
+	// be up yet at prober boot, or may reject an unconfigured site_id until
+	// an admin adds it — the prober should keep waiting rather than exit.
+	registerRetryInitial time.Duration
+	registerRetryMax     time.Duration
 }
 
 func New(cfg *config.Prober, log *slog.Logger) *Prober {
@@ -30,15 +36,17 @@ func New(cfg *config.Prober, log *slog.Logger) *Prober {
 		timeout = 10 * time.Second
 	}
 	return &Prober{
-		cfg:    cfg,
-		client: apiclient.New(cfg.ControlAPIURL, timeout+5*time.Second),
-		log:    log,
+		cfg:                  cfg,
+		client:               apiclient.New(cfg.ControlAPIURL, timeout+5*time.Second),
+		log:                  log,
+		registerRetryInitial: 3 * time.Second,
+		registerRetryMax:     30 * time.Second,
 	}
 }
 
 func (p *Prober) Run(ctx context.Context) error {
-	if err := p.register(ctx); err != nil {
-		return fmt.Errorf("register: %w", err)
+	if err := p.registerWithRetry(ctx); err != nil {
+		return err
 	}
 
 	interval := time.Duration(p.cfg.PollIntervalSeconds) * time.Second
@@ -70,6 +78,30 @@ func (p *Prober) register(ctx context.Context) error {
 	return nil
 }
 
+// registerWithRetry retries register with capped exponential backoff until
+// it succeeds or ctx is cancelled — see agentcore.Agent.registerWithRetry
+// for the identical rationale (control-api may start later, or an admin may
+// add this site_id to its config later).
+func (p *Prober) registerWithRetry(ctx context.Context) error {
+	delay := p.registerRetryInitial
+	for {
+		err := p.register(ctx)
+		if err == nil {
+			return nil
+		}
+		p.log.Warn("registration failed, will retry", "err", err, "retry_in", delay)
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-time.After(delay):
+		}
+		delay *= 2
+		if delay > p.registerRetryMax {
+			delay = p.registerRetryMax
+		}
+	}
+}
+
 type assignment struct {
 	IPID      int64  `json:"ip_id"`
 	IPAddress string `json:"ip_address"`

internal/probercore/probercore_test.go

@@ -7,6 +7,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -95,6 +96,86 @@ func TestPollOnceSkipsAssignmentsWhenHeartbeatFails(t *testing.T) {
 	}
 }
 
+// TestRegisterWithRetrySucceedsAfterSiteConfigured mirrors an admin adding
+// this prober's site_id to control-api's config after the prober has
+// already started: registration is rejected with 400 until then, and the
+// prober must keep retrying rather than give up.
+func TestRegisterWithRetrySucceedsAfterSiteConfigured(t *testing.T) {
+	var attempts int32
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /api/v1/probers/register", func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&attempts, 1)
+		if n < 3 {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte(`{"error":"unknown site_id: site-1"}`))
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+	})
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	p := &Prober{
+		cfg:                  &config.Prober{SiteID: "site-1", ControlAPIURL: ts.URL},
+		client:               apiclient.New(ts.URL, 5*time.Second),
+		log:                  testLogger(),
+		registerRetryInitial: time.Millisecond,
+		registerRetryMax:     5 * time.Millisecond,
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	if err := p.registerWithRetry(ctx); err != nil {
+		t.Fatalf("expected eventual success, got err: %v", err)
+	}
+	if got := atomic.LoadInt32(&attempts); got != 3 {
+		t.Fatalf("expected exactly 3 attempts, got %d", got)
+	}
+}
+
+// TestRegisterWithRetryStopsOnCancel confirms a prober waiting on an
+// unreachable/unconfigured control-api can still be shut down promptly.
+func TestRegisterWithRetryStopsOnCancel(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /api/v1/probers/register", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusBadRequest)
+	})
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	p := &Prober{
+		cfg:                  &config.Prober{SiteID: "site-1", ControlAPIURL: ts.URL},
+		client:               apiclient.New(ts.URL, 5*time.Second),
+		log:                  testLogger(),
+		registerRetryInitial: 10 * time.Millisecond,
+		registerRetryMax:     10 * time.Millisecond,
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		time.Sleep(30 * time.Millisecond)
+		cancel()
+	}()
+
+	var err error
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		err = p.registerWithRetry(ctx)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("registerWithRetry did not return after ctx cancellation")
+	}
+	if err != context.Canceled {
+		t.Fatalf("expected context.Canceled, got %v", err)
+	}
+}
+
 // TestExtraChecksForPort confirms only ports 443 (TLS) and 22 (SSH) get an
 // extra protocol check beyond the baseline TCPConnect every port gets.
 func TestExtraChecksForPort(t *testing.T) {