Merge pull request 'Relay installer logs to VictoriaLogs via POST /logs' (#9) from benvin/log-relay into main

Reviewed-on: #9

.woodpecker/pre-commit.yaml

@@ -3,7 +3,18 @@ when:
 
 steps:
   - name: pre-commit
-    image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
+    image: "artifactapi.k8s.syd1.au.unkin.net/docker-internal/gobuilder:0.1.2-alma9"
+    environment:
+      GOCACHE_S3_BUCKET: gocache
+      GOCACHE_S3_REGION: us-east-1
+      GOCACHE_S3_ENDPOINT_URL: "https://s3.ceph.unkin.net"
+      GOCACHE_S3_PATH_STYLE: "true"
+      GOCACHE_KEY_PREFIX: ci-bootapi
+      GOCACHEPROG: "go-cache-plugin --cache-dir=/tmp/gocache"
+      AWS_ACCESS_KEY_ID:
+        from_secret: GOCACHE_AWS_ACCESS_KEY_ID
+      AWS_SECRET_ACCESS_KEY:
+        from_secret: GOCACHE_AWS_SECRET_ACCESS_KEY
     commands:
       - uvx pre-commit run --all-files
     backend_options:

.woodpecker/release.yaml

@@ -6,7 +6,18 @@ when:
 # container image is built+pushed separately by docker.yaml.
 steps:
   - name: test
-    image: golang:1.25
+    image: "artifactapi.k8s.syd1.au.unkin.net/docker-internal/gobuilder:0.1.2-alma9"
+    environment:
+      GOCACHE_S3_BUCKET: gocache
+      GOCACHE_S3_REGION: us-east-1
+      GOCACHE_S3_ENDPOINT_URL: "https://s3.ceph.unkin.net"
+      GOCACHE_S3_PATH_STYLE: "true"
+      GOCACHE_KEY_PREFIX: ci-bootapi
+      GOCACHEPROG: "go-cache-plugin --cache-dir=/tmp/gocache"
+      AWS_ACCESS_KEY_ID:
+        from_secret: GOCACHE_AWS_ACCESS_KEY_ID
+      AWS_SECRET_ACCESS_KEY:
+        from_secret: GOCACHE_AWS_SECRET_ACCESS_KEY
     commands:
       - go test -race ./...
     backend_options:
@@ -21,7 +32,18 @@ steps:
             cpu: 2
 
   - name: build
-    image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
+    image: "artifactapi.k8s.syd1.au.unkin.net/docker-internal/gobuilder:0.1.2-alma9"
+    environment:
+      GOCACHE_S3_BUCKET: gocache
+      GOCACHE_S3_REGION: us-east-1
+      GOCACHE_S3_ENDPOINT_URL: "https://s3.ceph.unkin.net"
+      GOCACHE_S3_PATH_STYLE: "true"
+      GOCACHE_KEY_PREFIX: ci-bootapi
+      GOCACHEPROG: "go-cache-plugin --cache-dir=/tmp/gocache"
+      AWS_ACCESS_KEY_ID:
+        from_secret: GOCACHE_AWS_ACCESS_KEY_ID
+      AWS_SECRET_ACCESS_KEY:
+        from_secret: GOCACHE_AWS_SECRET_ACCESS_KEY
     commands:
       - make release-binaries VERSION=${CI_COMMIT_TAG}
     depends_on: [test]

.woodpecker/test.yaml

@@ -18,7 +18,18 @@ steps:
             cpu: 2
 
   - name: test
-    image: golang:1.25
+    image: "artifactapi.k8s.syd1.au.unkin.net/docker-internal/gobuilder:0.1.2-alma9"
+    environment:
+      GOCACHE_S3_BUCKET: gocache
+      GOCACHE_S3_REGION: us-east-1
+      GOCACHE_S3_ENDPOINT_URL: "https://s3.ceph.unkin.net"
+      GOCACHE_S3_PATH_STYLE: "true"
+      GOCACHE_KEY_PREFIX: ci-bootapi
+      GOCACHEPROG: "go-cache-plugin --cache-dir=/tmp/gocache"
+      AWS_ACCESS_KEY_ID:
+        from_secret: GOCACHE_AWS_ACCESS_KEY_ID
+      AWS_SECRET_ACCESS_KEY:
+        from_secret: GOCACHE_AWS_SECRET_ACCESS_KEY
     commands:
       - go test -race ./...
     backend_options:

README.md

@@ -33,6 +33,7 @@ serves it. Templates are embedded defaults, overridable from a directory
 | `GET /ipxe/{mac}` · `GET /boot/ipxe?mac=` | iPXE boot script |
 | `GET /ks/{ident}` | rendered kickstart (MAC or hostname) |
 | `POST /provisioned/{ident}` | end-of-kickstart callback (token) → clears `pxe_enabled` in NetBox |
+| `POST /logs` | installer log relay (token) → VictoriaLogs `vlinsert` |
 | `GET /healthz` · `/readyz` · `/metrics` | health + Prometheus |
 
 The boot path is served over **plain HTTP** (PXE installers have no internal-CA
@@ -64,7 +65,7 @@ rationale in [docs/endpoints.md](docs/endpoints.md).
 Env-based (12-factor), see [`config.example.env`](config.example.env). Key vars:
 `BOOTAPI_NETBOX_URL`, `BOOTAPI_NETBOX_TOKEN[_FILE]`, `BOOTAPI_BASE_URL`,
 `BOOTAPI_BOOT_BASE_URL`, `BOOTAPI_ROOT_PASSWORD_HASH[_FILE]`,
-`BOOTAPI_UNKNOWN_MAC_FALLBACK`.
+`BOOTAPI_UNKNOWN_MAC_FALLBACK`, `BOOTAPI_VLINSERT_URL`.
 
 ## Development
 

cmd/bootapi/main.go

@@ -47,7 +47,10 @@ func main() {
 		slog.Warn("no NetBox token set (BOOTAPI_NETBOX_TOKEN/_FILE); NetBox reads will likely be denied")
 	}
 	if cfg.ProvisionToken == "" {
-		slog.Warn("no BOOTAPI_PROVISION_TOKEN set; the /provisioned callback is disabled (pxe_enabled will not auto-clear)")
+		slog.Warn("no BOOTAPI_PROVISION_TOKEN set; the /provisioned callback and /logs relay are disabled")
+	}
+	if cfg.VLInsertURL == "" {
+		slog.Warn("BOOTAPI_VLINSERT_URL is empty; the /logs installer log relay is disabled")
 	}
 
 	rcfg := render.RenderConfig{
@@ -92,6 +95,8 @@ func main() {
 		Cache:              cache,
 		UnknownMACFallback: cfg.UnknownMACFallback,
 		ProvisionToken:     cfg.ProvisionToken,
+		VLInsertURL:        cfg.VLInsertURL,
+		VLInsertTimeout:    cfg.VLInsertTimeout,
 		TLSAddr:            cfg.TLSListenAddr,
 		TLSCertFile:        cfg.TLSCertFile,
 		TLSKeyFile:         cfg.TLSKeyFile,

config.example.env

@@ -55,6 +55,15 @@ BOOTAPI_ARTIFACT_BASE_URL=https://artifactapi.k8s.syd1.au.unkin.net/api/v1/remot
 BOOTAPI_PROVISION_TOKEN=
 # BOOTAPI_PROVISION_TOKEN_FILE=/var/run/secrets/bootapi/provision_token
 
+# --- installer log relay (POST /logs -> VictoriaLogs vlinsert) ---
+# A host being discovered or installed is not in k8s (no vlagent) and has no
+# internal-CA trust or credentials for the HTTPS log ingest, so bootapi relays
+# its newline-delimited JSON logs. Guarded by BOOTAPI_PROVISION_TOKEN.
+# An EMPTY value disables the endpoint (it then 503s).
+BOOTAPI_VLINSERT_URL=http://vlinsert-logs.logging.svc.cluster.local:9481
+# Short on purpose: logs are best-effort, an install must not wait on the sink.
+BOOTAPI_VLINSERT_TIMEOUT=5s
+
 # --- puppet bootstrap targets (k8s puppetserver; baked into kickstart %post) ---
 BOOTAPI_PUPPET_SERVER=puppet.k8s.syd1.au.unkin.net
 BOOTAPI_PUPPET_CA_SERVER=puppetca.k8s.syd1.au.unkin.net

docs/endpoints.md

@@ -35,6 +35,7 @@ of the install.
 | GET | `/boot/ipxe?mac=...` | Query-string alias of `/ipxe/{mac}`. |
 | GET | `/ks/{ident}` | Rendered kickstart. `{ident}` is a MAC (auto-detected) or a hostname; trailing `.ks`/`.cfg` is stripped. |
 | POST | `/provisioned/{ident}` | End-of-kickstart callback; clears `pxe_enabled` in NetBox. **Token-guarded** (`Authorization: Bearer <BOOTAPI_PROVISION_TOKEN>`). |
+| POST | `/logs` | Relays a host's newline-delimited JSON install logs to VictoriaLogs. **Token-guarded** (same token). |
 | GET | `/healthz` | Liveness: always `200 ok`. |
 | GET | `/readyz` | Readiness: `200` once templates parsed. Does **not** probe NetBox. |
 | GET | `/metrics` | Prometheus metrics (see below). |
@@ -85,6 +86,33 @@ bad/missing token, `404` for an unknown host, `503` when no
 failure. The default kickstart templates call it from `%post` over plain HTTP
 (the token authenticates the call; no CA trust needed at install time).
 
+## The installer log relay
+
+`POST /logs` exists because a host being PXE-discovered or installed is not in
+Kubernetes, so the cluster's vlagent cannot collect its logs — if an install
+fails, the only record dies with the machine. That environment also has no
+internal-CA trust and no credentials for the HTTPS-only log ingest, and bootapi
+is already the plain-HTTP broker it can reach, so bootapi forwards for it.
+
+- Body: newline-delimited JSON, one log record per line (`application/x-ndjson`
+  or `application/json`), capped at **1 MiB**.
+- Auth: the same `BOOTAPI_PROVISION_TOKEN` as `/provisioned`, same fail-closed
+  behavior — `503` when no token (or no `BOOTAPI_VLINSERT_URL`) is configured,
+  `401` on a bad/missing token.
+- Forwarded as one short-timeout POST to
+  `{BOOTAPI_VLINSERT_URL}/insert/jsonline?_stream_fields=serial,phase&_msg_field=msg&_time_field=time`.
+  `serial` and `phase` are constant for a run and low-cardinality, so they key
+  the stream; MAC is per-NIC and goes in `extra_fields` so it stays searchable
+  without multiplying streams.
+- `extra_fields` carries only what bootapi *observes* rather than what the
+  client claims: the request's source IP (`src_ip`), plus the resolved NetBox
+  device name (`device`) when `?mac=` resolves. Resolution is optional — a miss
+  just omits the field.
+- Responses: `202` once the batch is accepted, `400` on an empty or oversized
+  body. A vlinsert failure is logged and counted but **still returns `202`** —
+  no retries, no buffering: a host must never block its install because the log
+  sink is down.
+
 ## Metrics
 
 All on `/metrics`, prefix `bootapi_`:
@@ -95,6 +123,8 @@ All on `/metrics`, prefix `bootapi_`:
 - `bootapi_netbox_lookup_duration_seconds{field}` — histogram.
 - `bootapi_netbox_cache_hits_total` / `bootapi_netbox_cache_misses_total`.
 - `bootapi_provisioned_total{result}` — result = `ok|unauthorized|notfound|error|disabled`.
+- `bootapi_log_relay_total{result}` — result = `ok|error|unauthorized|disabled`.
+- `bootapi_log_relay_lines_total` — installer log lines successfully relayed.
 - `bootapi_ipxe_gated_total` — known hosts served local-boot because `pxe_enabled=false`.
 - `bootapi_template_sync_total` / `bootapi_template_sync_failures_total` / `bootapi_template_generation` — template git-sync (see [template-authoring.md](template-authoring.md)).
 - standard Go/process collectors.

internal/config/config.go

@@ -79,6 +79,15 @@ type Config struct {
 	// endpoint (fail closed). Prefer ProvisionTokenFile in k8s.
 	ProvisionToken string
 
+	// VLInsertURL is the VictoriaLogs vlinsert base that POST /logs relays
+	// installer logs to. Empty disables the endpoint (it then 503s): a host
+	// being installed has no vlagent and no credentials for the HTTPS ingest,
+	// so bootapi relays for it.
+	VLInsertURL string
+	// VLInsertTimeout bounds the single best-effort forward attempt. Short on
+	// purpose — an install must not wait on the log sink.
+	VLInsertTimeout time.Duration
+
 	// PuppetServer / PuppetCAServer are baked into kickstart %post so the
 	// freshly-installed host checks in to the k8s puppetserver.
 	PuppetServer   string
@@ -118,6 +127,16 @@ func Load() (*Config, error) {
 	if err != nil {
 		return nil, fmt.Errorf("invalid BOOTAPI_TEMPLATE_GIT_INTERVAL: %w", err)
 	}
+	vlTimeout, err := time.ParseDuration(getenv("BOOTAPI_VLINSERT_TIMEOUT", "5s"))
+	if err != nil {
+		return nil, fmt.Errorf("invalid BOOTAPI_VLINSERT_TIMEOUT: %w", err)
+	}
+	// Unlike the other URLs, an explicitly EMPTY value is meaningful here: it
+	// disables the log relay, so LookupEnv rather than getenv.
+	vlURL, ok := os.LookupEnv("BOOTAPI_VLINSERT_URL")
+	if !ok {
+		vlURL = "http://vlinsert-logs.logging.svc.cluster.local:9481"
+	}
 
 	token, err := readSecret("BOOTAPI_NETBOX_TOKEN")
 	if err != nil {
@@ -169,6 +188,8 @@ func Load() (*Config, error) {
 		ArtifactBaseURL:     strings.TrimRight(getenv("BOOTAPI_ARTIFACT_BASE_URL", "https://artifactapi.k8s.syd1.au.unkin.net/api/v1/remote"), "/"),
 		BootBaseURL:         strings.TrimRight(os.Getenv("BOOTAPI_BOOT_BASE_URL"), "/"),
 		ProvisionToken:      provToken,
+		VLInsertURL:         strings.TrimRight(vlURL, "/"),
+		VLInsertTimeout:     vlTimeout,
 		PuppetServer:        getenv("BOOTAPI_PUPPET_SERVER", "puppet.k8s.syd1.au.unkin.net"),
 		PuppetCAServer:      getenv("BOOTAPI_PUPPET_CA_SERVER", "puppetca.k8s.syd1.au.unkin.net"),
 		PuppetCAURL:         getenv("BOOTAPI_PUPPET_CA_URL", "puppetca.k8s.syd1.au.unkin.net"),

internal/config/config_test.go

@@ -40,6 +40,34 @@ func TestLoadDefaults(t *testing.T) {
 	if c.ArtifactBaseURL != "https://artifactapi.k8s.syd1.au.unkin.net/api/v1/remote" {
 		t.Errorf("ArtifactBaseURL = %q", c.ArtifactBaseURL)
 	}
+	if c.VLInsertURL != "http://vlinsert-logs.logging.svc.cluster.local:9481" {
+		t.Errorf("VLInsertURL = %q", c.VLInsertURL)
+	}
+	if c.VLInsertTimeout != 5*time.Second {
+		t.Errorf("VLInsertTimeout = %v, want 5s", c.VLInsertTimeout)
+	}
+}
+
+func TestVLInsertURLEmptyDisablesRelay(t *testing.T) {
+	clearEnv(t)
+	// An explicitly empty value must NOT fall back to the default: it disables
+	// the /logs relay.
+	t.Setenv("BOOTAPI_VLINSERT_URL", "")
+	c, err := Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if c.VLInsertURL != "" {
+		t.Errorf("VLInsertURL = %q, want empty (relay disabled)", c.VLInsertURL)
+	}
+}
+
+func TestVLInsertBadTimeout(t *testing.T) {
+	clearEnv(t)
+	t.Setenv("BOOTAPI_VLINSERT_TIMEOUT", "soon")
+	if _, err := Load(); err == nil {
+		t.Fatal("expected error for invalid BOOTAPI_VLINSERT_TIMEOUT")
+	}
 }
 
 func TestCallbackBaseDefaultsToBase(t *testing.T) {

internal/server/metrics.go

@@ -28,6 +28,8 @@ type metrics struct {
 	netboxLookups  *prometheus.CounterVec // by field,result
 	netboxDuration *prometheus.HistogramVec
 	provisioned    *prometheus.CounterVec // by result
+	logRelay       *prometheus.CounterVec // by result
+	logLines       prometheus.Counter
 	ipxeGated      prometheus.Counter
 }
 
@@ -56,12 +58,20 @@ func newMetrics(cache cacheStats, git gitStats) *metrics {
 			Name: "bootapi_provisioned_total",
 			Help: "Provisioned callbacks, by result (ok|unauthorized|notfound|error|disabled).",
 		}, []string{"result"}),
+		logRelay: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "bootapi_log_relay_total",
+			Help: "Installer log batches relayed to VictoriaLogs, by result (ok|error|unauthorized|disabled).",
+		}, []string{"result"}),
+		logLines: prometheus.NewCounter(prometheus.CounterOpts{
+			Name: "bootapi_log_relay_lines_total",
+			Help: "Installer log lines successfully relayed to VictoriaLogs.",
+		}),
 		ipxeGated: prometheus.NewCounter(prometheus.CounterOpts{
 			Name: "bootapi_ipxe_gated_total",
 			Help: "Known hosts served the local-boot fallback because pxe_enabled=false.",
 		}),
 	}
-	reg.MustRegister(m.httpRequests, m.renders, m.netboxLookups, m.netboxDuration, m.provisioned, m.ipxeGated)
+	reg.MustRegister(m.httpRequests, m.renders, m.netboxLookups, m.netboxDuration, m.provisioned, m.logRelay, m.logLines, m.ipxeGated)
 	if cache != nil {
 		reg.MustRegister(newCacheCollector(cache))
 	}

internal/server/server.go

@@ -3,12 +3,16 @@
 package server
 
 import (
+	"bytes"
 	"context"
 	"crypto/subtle"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
+	"net"
 	"net/http"
+	"net/url"
 	"strings"
 	"sync"
 	"time"
@@ -30,9 +34,15 @@ type Server struct {
 	// fallback is the unknown-MAC iPXE behavior: "local" (safe default) or
 	// "shell" (debug).
 	fallback string
-	// provisionToken guards POST /provisioned; empty disables the endpoint.
+	// provisionToken guards POST /provisioned and POST /logs; empty disables
+	// both endpoints.
 	provisionToken string
 
+	// vlinsertURL is the VictoriaLogs vlinsert base POST /logs relays to;
+	// empty disables the endpoint. vlClient bounds the single forward attempt.
+	vlinsertURL string
+	vlClient    *http.Client
+
 	// TLS listener (optional); the plain-HTTP listener is always on.
 	tlsAddr string
 	tlsCert string
@@ -48,6 +58,8 @@ type Options struct {
 	GitStats           gitStats
 	UnknownMACFallback string
 	ProvisionToken     string
+	VLInsertURL        string
+	VLInsertTimeout    time.Duration
 	TLSAddr            string
 	TLSCertFile        string
 	TLSKeyFile         string
@@ -59,12 +71,18 @@ func New(o Options) *Server {
 	if fb == "" {
 		fb = "local"
 	}
+	timeout := o.VLInsertTimeout
+	if timeout <= 0 {
+		timeout = 5 * time.Second
+	}
 	return &Server{
 		nb:             o.NetBox,
 		engine:         o.Engine,
 		metrics:        newMetrics(o.Cache, o.GitStats),
 		fallback:       fb,
 		provisionToken: o.ProvisionToken,
+		vlinsertURL:    strings.TrimRight(o.VLInsertURL, "/"),
+		vlClient:       &http.Client{Timeout: timeout},
 		tlsAddr:        o.TLSAddr,
 		tlsCert:        o.TLSCertFile,
 		tlsKey:         o.TLSKeyFile,
@@ -92,6 +110,10 @@ func (s *Server) Router() http.Handler {
 	// End-of-kickstart callback: flips pxe_enabled off in NetBox. Token-guarded.
 	r.Post("/provisioned/{ident}", s.handleProvisioned)
 
+	// Installer log relay: a host being installed is not in Kubernetes, so
+	// vlagent cannot collect its logs. Token-guarded like /provisioned.
+	r.Post("/logs", s.handleLogs)
+
 	return r
 }
 
@@ -253,6 +275,96 @@ func (s *Server) handleProvisioned(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusNoContent)
 }
 
+// maxLogBody caps a relayed batch. An install's log stream is a handful of
+// lines per phase; bootapi is a relay, not a log buffer.
+const maxLogBody = 1 << 20 // 1 MiB
+
+// handleLogs relays newline-delimited JSON log records from a host that is
+// PXE-discovering or installing into VictoriaLogs. Such a host is not in
+// Kubernetes (no vlagent) and has no internal-CA trust or credentials for the
+// HTTPS log ingest, so bootapi — the plain-HTTP broker it can already reach —
+// forwards them. Best-effort: a dead log sink must never block an install, so
+// every outcome after authentication is 202.
+func (s *Server) handleLogs(w http.ResponseWriter, r *http.Request) {
+	if s.vlinsertURL == "" || s.provisionToken == "" {
+		http.Error(w, "log relay disabled: no vlinsert URL or no token configured", http.StatusServiceUnavailable)
+		s.metrics.logRelay.WithLabelValues("disabled").Inc()
+		return
+	}
+	if subtle.ConstantTimeCompare([]byte(bearer(r)), []byte(s.provisionToken)) != 1 {
+		http.Error(w, "invalid or missing provision token", http.StatusUnauthorized)
+		s.metrics.logRelay.WithLabelValues("unauthorized").Inc()
+		return
+	}
+	body, err := io.ReadAll(http.MaxBytesReader(w, r.Body, maxLogBody))
+	if err != nil {
+		http.Error(w, "log batch unreadable or larger than 1MiB", http.StatusBadRequest)
+		s.metrics.logRelay.WithLabelValues("error").Inc()
+		return
+	}
+	if len(bytes.TrimSpace(body)) == 0 {
+		http.Error(w, "empty log batch", http.StatusBadRequest)
+		s.metrics.logRelay.WithLabelValues("error").Inc()
+		return
+	}
+
+	lines := bytes.Count(bytes.TrimRight(body, "\n"), []byte("\n")) + 1
+	if err := s.relayLogs(r.Context(), body, s.observedFields(r)); err != nil {
+		slog.Error("log relay to vlinsert failed; dropping batch", "lines", lines, "err", err)
+		s.metrics.logRelay.WithLabelValues("error").Inc()
+	} else {
+		s.metrics.logRelay.WithLabelValues("ok").Inc()
+		s.metrics.logLines.Add(float64(lines))
+	}
+	s.ok(w, http.StatusAccepted, "text/plain", []byte("accepted\n"), "logs")
+}
+
+// relayLogs makes one short-timeout POST to vlinsert's jsonline endpoint.
+// serial and phase are constant for a run and low-cardinality, so they key the
+// stream; MAC is per-NIC and rides in extra_fields so it stays searchable
+// without multiplying streams.
+func (s *Server) relayLogs(ctx context.Context, body []byte, extra string) error {
+	q := url.Values{
+		"_stream_fields": {"serial,phase"},
+		"_msg_field":     {"msg"},
+		"_time_field":    {"time"},
+	}
+	if extra != "" {
+		q.Set("extra_fields", extra)
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.vlinsertURL+"/insert/jsonline?"+q.Encode(), bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-ndjson")
+	resp, err := s.vlClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = resp.Body.Close() }()
+	_, _ = io.Copy(io.Discard, resp.Body)
+	if resp.StatusCode >= http.StatusMultipleChoices {
+		return fmt.Errorf("vlinsert: %s", resp.Status)
+	}
+	return nil
+}
+
+// observedFields builds the extra_fields value from what bootapi observes
+// rather than what the client claims: the source IP, plus the NetBox device
+// name when ?mac= resolves. Resolution is optional — a miss just omits it.
+func (s *Server) observedFields(r *http.Request) string {
+	fields := []string{}
+	if ip, _, err := net.SplitHostPort(r.RemoteAddr); err == nil && ip != "" {
+		fields = append(fields, "src_ip="+ip)
+	}
+	if mac := r.URL.Query().Get("mac"); looksLikeMAC(mac) {
+		if host, err := s.lookup(r.Context(), "mac", mac); err == nil {
+			fields = append(fields, "device="+host.Hostname)
+		}
+	}
+	return strings.Join(fields, ",")
+}
+
 // bearer extracts a token from "Authorization: Bearer <t>" or a bare "token"
 // header.
 func bearer(r *http.Request) string {

internal/server/server_test.go

@@ -2,10 +2,13 @@ package server
 
 import (
 	"context"
+	"io"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"testing"
+	"time"
 
 	"git.unkin.net/unkin/bootapi/internal/model"
 	"git.unkin.net/unkin/bootapi/internal/netbox"
@@ -68,6 +71,11 @@ func newTestServer(t *testing.T, nb netbox.API, fallback string) *Server {
 }
 
 func newTestServerToken(t *testing.T, nb netbox.API, fallback, provToken string) *Server {
+	t.Helper()
+	return newTestServerLogs(t, nb, fallback, provToken, "")
+}
+
+func newTestServerLogs(t *testing.T, nb netbox.API, fallback, provToken, vlURL string) *Server {
 	t.Helper()
 	set, err := render.BuildSet(templates.FS, nil)
 	if err != nil {
@@ -80,7 +88,10 @@ func newTestServerToken(t *testing.T, nb netbox.API, fallback, provToken string)
 		DefaultDomain: "main.unkin.net", DefaultTemplate: "almalinux9",
 		RootPasswordHash: "$6$abc$def",
 	}, set)
-	return New(Options{NetBox: nb, Engine: eng, UnknownMACFallback: fallback, ProvisionToken: provToken})
+	return New(Options{
+		NetBox: nb, Engine: eng, UnknownMACFallback: fallback,
+		ProvisionToken: provToken, VLInsertURL: vlURL, VLInsertTimeout: 2 * time.Second,
+	})
 }
 
 func do(t *testing.T, h http.Handler, path string) *httptest.ResponseRecorder {
@@ -291,3 +302,187 @@ func TestLooksLikeMAC(t *testing.T) {
 		}
 	}
 }
+
+// vlStub is a stand-in vlinsert that records what bootapi forwarded.
+type vlStub struct {
+	srv    *httptest.Server
+	hits   int
+	path   string
+	query  url.Values
+	body   string
+	ctype  string
+	status int
+}
+
+func newVLStub(t *testing.T, status int) *vlStub {
+	t.Helper()
+	v := &vlStub{status: status}
+	v.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		b, err := io.ReadAll(r.Body)
+		if err != nil {
+			t.Errorf("vlinsert stub read body: %v", err)
+		}
+		v.hits++
+		v.path, v.query, v.body, v.ctype = r.URL.Path, r.URL.Query(), string(b), r.Header.Get("Content-Type")
+		w.WriteHeader(v.status)
+	}))
+	t.Cleanup(v.srv.Close)
+	return v
+}
+
+func postLogs(t *testing.T, h http.Handler, path, token, body string) *httptest.ResponseRecorder {
+	t.Helper()
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(body))
+	req.Header.Set("Content-Type", "application/x-ndjson")
+	if token != "" {
+		req.Header.Set("Authorization", "Bearer "+token)
+	}
+	h.ServeHTTP(rec, req)
+	return rec
+}
+
+func TestLogRelayForwardsToVLInsert(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	res := &fakeNB{byMAC: map[string]*model.Host{"aa:bb:cc:00:11:22": testHost()}}
+	h := newTestServerLogs(t, res, "local", "prov-secret", vl.srv.URL).Router()
+
+	batch := `{"time":"2026-10-03T00:00:00Z","serial":"SN1","phase":"discovery","msg":"hello"}`
+	rec := postLogs(t, h, "/logs?mac=aa:bb:cc:00:11:22", "prov-secret", batch+"\n")
+	if rec.Code != http.StatusAccepted {
+		t.Fatalf("status = %d, want 202\n%s", rec.Code, rec.Body.String())
+	}
+	if vl.hits != 1 {
+		t.Fatalf("vlinsert hits = %d, want 1", vl.hits)
+	}
+	if vl.path != "/insert/jsonline" {
+		t.Errorf("path = %q", vl.path)
+	}
+	for k, want := range map[string]string{
+		"_stream_fields": "serial,phase",
+		"_msg_field":     "msg",
+		"_time_field":    "time",
+	} {
+		if got := vl.query.Get(k); got != want {
+			t.Errorf("query %s = %q, want %q", k, got, want)
+		}
+	}
+	// extra_fields carries only what bootapi observed, not client claims.
+	if got := vl.query.Get("extra_fields"); got != "src_ip=192.0.2.1,device=web01" {
+		t.Errorf("extra_fields = %q", got)
+	}
+	if strings.TrimSpace(vl.body) != batch {
+		t.Errorf("forwarded body = %q", vl.body)
+	}
+	if vl.ctype != "application/x-ndjson" {
+		t.Errorf("forwarded content-type = %q", vl.ctype)
+	}
+}
+
+func TestLogRelayUnresolvedMACStillForwards(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	h := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL).Router()
+
+	rec := postLogs(t, h, "/logs?mac=de:ad:be:ef:00:00", "prov-secret", `{"msg":"x"}`+"\n")
+	if rec.Code != http.StatusAccepted || vl.hits != 1 {
+		t.Fatalf("status = %d hits = %d, want 202/1", rec.Code, vl.hits)
+	}
+	if got := vl.query.Get("extra_fields"); got != "src_ip=192.0.2.1" {
+		t.Errorf("unresolved MAC must omit device: extra_fields = %q", got)
+	}
+}
+
+func TestLogRelayAuth(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	h := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL).Router()
+
+	if rec := postLogs(t, h, "/logs", "wrong", `{"msg":"x"}`); rec.Code != http.StatusUnauthorized {
+		t.Errorf("wrong token: status = %d, want 401", rec.Code)
+	}
+	if rec := postLogs(t, h, "/logs", "", `{"msg":"x"}`); rec.Code != http.StatusUnauthorized {
+		t.Errorf("no token: status = %d, want 401", rec.Code)
+	}
+	if vl.hits != 0 {
+		t.Errorf("unauthorized calls must not forward, hits = %d", vl.hits)
+	}
+}
+
+func TestLogRelayDisabledWithoutProvisionToken(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	h := newTestServerLogs(t, &fakeNB{}, "local", "", vl.srv.URL).Router()
+	if rec := postLogs(t, h, "/logs", "anything", `{"msg":"x"}`); rec.Code != http.StatusServiceUnavailable {
+		t.Errorf("status = %d, want 503 when no token configured", rec.Code)
+	}
+	if vl.hits != 0 {
+		t.Errorf("disabled relay must not forward, hits = %d", vl.hits)
+	}
+}
+
+func TestLogRelayDisabledWithoutVLInsertURL(t *testing.T) {
+	h := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", "").Router()
+	if rec := postLogs(t, h, "/logs", "prov-secret", `{"msg":"x"}`); rec.Code != http.StatusServiceUnavailable {
+		t.Errorf("status = %d, want 503 when BOOTAPI_VLINSERT_URL is empty", rec.Code)
+	}
+}
+
+func TestLogRelayEmptyBody(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	h := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL).Router()
+	if rec := postLogs(t, h, "/logs", "prov-secret", "\n  \n"); rec.Code != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400 for an empty batch", rec.Code)
+	}
+	if vl.hits != 0 {
+		t.Errorf("empty batch must not forward, hits = %d", vl.hits)
+	}
+}
+
+func TestLogRelayOversizedBody(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	h := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL).Router()
+	big := strings.Repeat("x", maxLogBody+1)
+	if rec := postLogs(t, h, "/logs", "prov-secret", big); rec.Code != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400 for an oversized batch", rec.Code)
+	}
+	if vl.hits != 0 {
+		t.Errorf("oversized batch must not forward, hits = %d", vl.hits)
+	}
+}
+
+func TestLogRelayVLInsertFailureStillAccepts(t *testing.T) {
+	vl := newVLStub(t, http.StatusInternalServerError)
+	srv := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL)
+	h := srv.Router()
+
+	// A dead log sink must never block an install.
+	if rec := postLogs(t, h, "/logs", "prov-secret", `{"msg":"x"}`+"\n"); rec.Code != http.StatusAccepted {
+		t.Fatalf("status = %d, want 202 even when vlinsert fails", rec.Code)
+	}
+	body := do(t, h, "/metrics").Body.String()
+	if !strings.Contains(body, `bootapi_log_relay_total{result="error"} 1`) {
+		t.Error("error result not counted")
+	}
+	if strings.Contains(body, "bootapi_log_relay_lines_total 1") {
+		t.Error("dropped lines must not be counted as relayed")
+	}
+}
+
+func TestLogRelayLineCountMetric(t *testing.T) {
+	vl := newVLStub(t, http.StatusNoContent)
+	srv := newTestServerLogs(t, &fakeNB{}, "local", "prov-secret", vl.srv.URL)
+	h := srv.Router()
+
+	batch := `{"msg":"a"}` + "\n" + `{"msg":"b"}` + "\n" + `{"msg":"c"}` + "\n"
+	if rec := postLogs(t, h, "/logs", "prov-secret", batch); rec.Code != http.StatusAccepted {
+		t.Fatalf("status = %d", rec.Code)
+	}
+	body := do(t, h, "/metrics").Body.String()
+	for _, want := range []string{
+		`bootapi_log_relay_total{result="ok"} 1`,
+		"bootapi_log_relay_lines_total 3",
+		`bootapi_http_requests_total{endpoint="logs",status="2xx"} 1`,
+	} {
+		if !strings.Contains(body, want) {
+			t.Errorf("metrics missing %q", want)
+		}
+	}
+}