Implement target selection, autodiscovery via aggregator, implement listTargets

README.md

@@ -32,7 +32,10 @@ DESIGN
 ```
 nginx-logtail/
 ├── proto/
-│   └── logtail.proto                  # shared protobuf definitions
+│   ├── logtail.proto                  # shared protobuf definitions
+│   └── logtailpb/
+│       ├── logtail.pb.go              # generated: messages, enums
+│       └── logtail_grpc.pb.go         # generated: service stubs
 ├── internal/
 │   └── store/
 │       └── store.go                   # shared types: Tuple4, Entry, Snapshot, ring helpers
@@ -48,6 +51,7 @@ nginx-logtail/
     │   ├── subscriber.go              # one goroutine per collector; StreamSnapshots with backoff
     │   ├── merger.go                  # delta-merge: O(snapshot_size) per update
     │   ├── cache.go                   # tick-based ring buffer cache served to clients
+    │   ├── registry.go                # TargetRegistry: addr→name map updated from snapshot sources
     │   └── server.go                  # gRPC server (same surface as collector)
     ├── frontend/
     │   ├── main.go
@@ -66,7 +70,8 @@ nginx-logtail/
         ├── format.go                  # printTable, fmtCount, fmtTime, targetHeader
         ├── cmd_topn.go                # topn: concurrent fan-out, table + JSON output
         ├── cmd_trend.go               # trend: concurrent fan-out, table + JSON output
-        └── cmd_stream.go              # stream: multiplexed streams, auto-reconnect
+        ├── cmd_stream.go              # stream: multiplexed streams, auto-reconnect
+        └── cmd_targets.go             # targets: list collectors known to the endpoint
 ```
 
 ## Data Model
@@ -178,13 +183,23 @@ message Snapshot {
   repeated TopNEntry entries   = 3;  // full top-50K for this bucket
 }
 
+// Target discovery: list the collectors behind the queried endpoint
+message ListTargetsRequest {}
+message TargetInfo {
+  string name = 1;  // display name (--source value from the collector)
+  string addr = 2;  // gRPC address; empty string means "this endpoint itself"
+}
+message ListTargetsResponse { repeated TargetInfo targets = 1; }
+
 service LogtailService {
   rpc TopN(TopNRequest)                returns (TopNResponse);
   rpc Trend(TrendRequest)              returns (TrendResponse);
   rpc StreamSnapshots(SnapshotRequest) returns (stream Snapshot);
+  rpc ListTargets(ListTargetsRequest)  returns (ListTargetsResponse);
 }
 // Both collector and aggregator implement LogtailService.
 // The aggregator's StreamSnapshots re-streams the merged view.
+// ListTargets: aggregator returns all configured collectors; collector returns itself.
 ```
 
 ## Program 1 — Collector
@@ -259,10 +274,18 @@ service LogtailService {
 - Same tiered ring structure as the collector store; populated from `merger.TopK()` each tick.
 - `QueryTopN`, `QueryTrend`, `Subscribe`/`Unsubscribe` — identical interface to collector store.
 
+### registry.go
+- **`TargetRegistry`**: `sync.RWMutex`-protected `map[addr → name]`. Initialised with the
+  configured collector addresses; display names are updated from the `source` field of the first
+  snapshot received from each collector.
+- `Targets()` returns a stable sorted slice of `{name, addr}` pairs for `ListTargets` responses.
+
 ### server.go
 - Implements `LogtailService` backed by the cache (not live fan-out).
 - `StreamSnapshots` re-streams merged fine snapshots; usable by a second-tier aggregator or
   monitoring system.
+- `ListTargets` returns the current `TargetRegistry` contents — all configured collectors with
+  their display names and gRPC addresses.
 
 ## Program 3 — Frontend
 
@@ -278,8 +301,13 @@ service LogtailService {
   `store.ParseStatusExpr` into `(value, StatusOp)` for the filter protobuf.
 - **Regex filters**: `f_website_re` and `f_uri_re` hold RE2 patterns; compiled once per request
   into `store.CompiledFilter` before the query-loop iteration. Invalid regexes match nothing.
-- `TopN` and `Trend` RPCs issued **concurrently** (both with a 5 s deadline); page renders with
+- `TopN`, `Trend`, and `ListTargets` RPCs issued **concurrently** (all with a 5 s deadline); page
-  whatever completes. Trend failure suppresses the sparkline without erroring the page.
+  renders with whatever completes. Trend failure suppresses the sparkline; `ListTargets` failure
+  hides the source picker — both are non-fatal.
+- **Source picker**: `ListTargets` result drives a `source:` tab row. Clicking a collector tab
+  sets `target=` to that collector's address, querying it directly. The "all" tab resets to the
+  default aggregator. Picker is hidden when `ListTargets` returns ≤0 collectors (direct collector
+  mode).
 - **Drilldown**: clicking a table row adds the current dimension's filter and advances `by` through
   `website → prefix → uri → status → website` (cycles).
 - **`raw=1`**: returns the TopN result as JSON — same URL, no CLI needed for scripting.
@@ -305,6 +333,7 @@ service LogtailService {
 logtail-cli topn    [flags]   ranked label → count table (exits after one response)
 logtail-cli trend   [flags]   per-bucket time series (exits after one response)
 logtail-cli stream  [flags]   live snapshot feed (runs until Ctrl-C, auto-reconnects)
+logtail-cli targets [flags]   list targets known to the queried endpoint
 ```
 
 ### Flags
@@ -364,3 +393,4 @@ with a non-zero code on gRPC error.
 | Status filter as expression string (`!=200`, `>=400`) | Operator-friendly; parsed once at query boundary, encoded as `(int32, StatusOp)` in proto |
 | Regex filters compiled once per query (`CompiledFilter`) | Up to 288 × 5 000 per-entry calls — compiling per-entry would dominate query latency |
 | Filter expression box (`q=`) redirects to canonical URL | Filter state stays in individual `f_*` params; URLs remain shareable and bookmarkable |
+| `ListTargets` + frontend source picker (no Tuple5) | "Which nginx is busiest?" answered by switching `target=` to a collector; no data model changes, no extra memory |

cmd/aggregator/aggregator_test.go

@@ -287,8 +287,8 @@ func TestGRPCEndToEnd(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	go NewCollectorSub(addr1, merger).Run(ctx)
+	go NewCollectorSub(addr1, merger, NewTargetRegistry(nil)).Run(ctx)
-	go NewCollectorSub(addr2, merger).Run(ctx)
+	go NewCollectorSub(addr2, merger, NewTargetRegistry(nil)).Run(ctx)
 
 	// Wait for both snapshots to be applied.
 	deadline := time.Now().Add(3 * time.Second)
@@ -309,7 +309,7 @@ func TestGRPCEndToEnd(t *testing.T) {
 		t.Fatal(err)
 	}
 	grpcSrv := grpc.NewServer()
-	pb.RegisterLogtailServiceServer(grpcSrv, NewServer(cache, "agg-test"))
+	pb.RegisterLogtailServiceServer(grpcSrv, NewServer(cache, "agg-test", NewTargetRegistry(nil)))
 	go grpcSrv.Serve(lis)
 	defer grpcSrv.Stop()
 
@@ -399,8 +399,8 @@ func TestDegradedCollector(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	go NewCollectorSub(addr1, merger).Run(ctx)
+	go NewCollectorSub(addr1, merger, NewTargetRegistry(nil)).Run(ctx)
-	go NewCollectorSub(addr2, merger).Run(ctx)
+	go NewCollectorSub(addr2, merger, NewTargetRegistry(nil)).Run(ctx)
 
 	// Wait for col1's data to appear.
 	deadline := time.Now().Add(3 * time.Second)

cmd/aggregator/main.go

@@ -27,16 +27,21 @@ func main() {
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()
 
-	merger := NewMerger()
+	var collectorAddrs []string
-	cache := NewCache(merger, *source)
-	go cache.Run(ctx)
-
 	for _, addr := range strings.Split(*collectors, ",") {
 		addr = strings.TrimSpace(addr)
-		if addr == "" {
+		if addr != "" {
-			continue
+			collectorAddrs = append(collectorAddrs, addr)
 		}
-		sub := NewCollectorSub(addr, merger)
+	}
+
+	merger := NewMerger()
+	cache := NewCache(merger, *source)
+	registry := NewTargetRegistry(collectorAddrs)
+	go cache.Run(ctx)
+
+	for _, addr := range collectorAddrs {
+		sub := NewCollectorSub(addr, merger, registry)
 		go sub.Run(ctx)
 		log.Printf("aggregator: subscribing to collector %s", addr)
 	}
@@ -46,7 +51,7 @@ func main() {
 		log.Fatalf("aggregator: failed to listen on %s: %v", *listen, err)
 	}
 	grpcServer := grpc.NewServer()
-	pb.RegisterLogtailServiceServer(grpcServer, NewServer(cache, *source))
+	pb.RegisterLogtailServiceServer(grpcServer, NewServer(cache, *source, registry))
 
 	go func() {
 		log.Printf("aggregator: gRPC listening on %s (source=%s)", *listen, *source)

cmd/aggregator/registry.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"sort"
+	"sync"
+)
+
+// TargetInfo holds the display name and gRPC address of one collector target.
+type TargetInfo struct {
+	Name string // collector --source value, falls back to addr until first snapshot
+	Addr string // configured gRPC address
+}
+
+// TargetRegistry tracks addr → display name for all configured collectors.
+// Names default to the addr and are updated to the collector's --source value
+// when the first snapshot arrives.
+type TargetRegistry struct {
+	mu    sync.RWMutex
+	names map[string]string // addr → current name
+}
+
+func NewTargetRegistry(addrs []string) *TargetRegistry {
+	names := make(map[string]string, len(addrs))
+	for _, a := range addrs {
+		names[a] = a // default until first snapshot
+	}
+	return &TargetRegistry{names: names}
+}
+
+// SetName updates the display name for addr (called when a snapshot arrives).
+func (r *TargetRegistry) SetName(addr, name string) {
+	r.mu.Lock()
+	r.names[addr] = name
+	r.mu.Unlock()
+}
+
+// Targets returns all registered targets sorted by addr.
+func (r *TargetRegistry) Targets() []TargetInfo {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	out := make([]TargetInfo, 0, len(r.names))
+	for addr, name := range r.names {
+		out = append(out, TargetInfo{Name: name, Addr: addr})
+	}
+	sort.Slice(out, func(i, j int) bool { return out[i].Addr < out[j].Addr })
+	return out
+}

cmd/aggregator/server.go

@@ -16,10 +16,11 @@ type Server struct {
 	pb.UnimplementedLogtailServiceServer
 	cache    *Cache
 	source   string
+	registry *TargetRegistry
 }
 
-func NewServer(cache *Cache, source string) *Server {
+func NewServer(cache *Cache, source string, registry *TargetRegistry) *Server {
-	return &Server{cache: cache, source: source}
+	return &Server{cache: cache, source: source, registry: registry}
 }
 
 func (srv *Server) TopN(_ context.Context, req *pb.TopNRequest) (*pb.TopNResponse, error) {
@@ -53,6 +54,16 @@ func (srv *Server) Trend(_ context.Context, req *pb.TrendRequest) (*pb.TrendResp
 	return resp, nil
 }
 
+func (srv *Server) ListTargets(_ context.Context, _ *pb.ListTargetsRequest) (*pb.ListTargetsResponse, error) {
+	resp := &pb.ListTargetsResponse{}
+	if srv.registry != nil {
+		for _, t := range srv.registry.Targets() {
+			resp.Targets = append(resp.Targets, &pb.TargetInfo{Name: t.Name, Addr: t.Addr})
+		}
+	}
+	return resp, nil
+}
+
 func (srv *Server) StreamSnapshots(_ *pb.SnapshotRequest, stream grpc.ServerStreamingServer[pb.Snapshot]) error {
 	ch := srv.cache.Subscribe()
 	defer srv.cache.Unsubscribe(ch)

cmd/aggregator/subscriber.go

@@ -17,10 +17,11 @@ import (
 type CollectorSub struct {
 	addr     string
 	merger   *Merger
+	registry *TargetRegistry
 }
 
-func NewCollectorSub(addr string, merger *Merger) *CollectorSub {
+func NewCollectorSub(addr string, merger *Merger, registry *TargetRegistry) *CollectorSub {
-	return &CollectorSub{addr: addr, merger: merger}
+	return &CollectorSub{addr: addr, merger: merger, registry: registry}
 }
 
 // Run blocks until ctx is cancelled.
@@ -92,6 +93,7 @@ func (cs *CollectorSub) stream(ctx context.Context) (bool, error) {
 			return gotOne, err
 		}
 		gotOne = true
+		cs.registry.SetName(cs.addr, snap.Source)
 		cs.merger.Apply(snap)
 	}
 }

cmd/cli/cmd_targets.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"os"
+	"time"
+
+	pb "git.ipng.ch/ipng/nginx-logtail/proto/logtailpb"
+)
+
+func runTargets(args []string) {
+	fs := flag.NewFlagSet("targets", flag.ExitOnError)
+	sf, target := bindShared(fs)
+	fs.Usage = func() {
+		fmt.Fprintln(os.Stderr, "usage: logtail-cli targets [--target host:port] [--json]")
+		fs.PrintDefaults()
+	}
+	fs.Parse(args)
+	sf.resolve(*target)
+
+	for _, addr := range sf.targets {
+		conn, client, err := dial(addr)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "targets: cannot connect to %s: %v\n", addr, err)
+			continue
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		resp, err := client.ListTargets(ctx, &pb.ListTargetsRequest{})
+		cancel()
+		conn.Close()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "targets: %s: %v\n", addr, err)
+			continue
+		}
+
+		if sf.jsonOut {
+			type row struct {
+				QueryTarget string `json:"query_target"`
+				Name        string `json:"name"`
+				Addr        string `json:"addr"`
+			}
+			for _, t := range resp.Targets {
+				json.NewEncoder(os.Stdout).Encode(row{QueryTarget: addr, Name: t.Name, Addr: t.Addr})
+			}
+		} else {
+			if len(sf.targets) > 1 {
+				fmt.Println(targetHeader(addr, "", len(sf.targets)))
+			}
+			for _, t := range resp.Targets {
+				addrCol := t.Addr
+				if addrCol == "" {
+					addrCol = "(self)"
+				}
+				fmt.Printf("%-40s  %s\n", t.Name, addrCol)
+			}
+		}
+	}
+}

cmd/cli/main.go

@@ -11,6 +11,7 @@ Usage:
   logtail-cli topn    [flags]   ranked label → count list
   logtail-cli trend   [flags]   per-minute time series
   logtail-cli stream  [flags]   live snapshot feed
+  logtail-cli targets [flags]   list targets known to the queried endpoint
 
 Subcommand flags (all subcommands):
   --target  host:port[,host:port,...]  endpoints to query (default: localhost:9090)
@@ -43,6 +44,8 @@ func main() {
 		runTrend(os.Args[2:])
 	case "stream":
 		runStream(os.Args[2:])
+	case "targets":
+		runTargets(os.Args[2:])
 	case "-h", "--help", "help":
 		fmt.Print(usage)
 	default:

cmd/collector/server.go

@@ -56,6 +56,12 @@ func (srv *Server) Trend(_ context.Context, req *pb.TrendRequest) (*pb.TrendResp
 	return resp, nil
 }
 
+func (srv *Server) ListTargets(_ context.Context, _ *pb.ListTargetsRequest) (*pb.ListTargetsResponse, error) {
+	return &pb.ListTargetsResponse{
+		Targets: []*pb.TargetInfo{{Name: srv.source, Addr: ""}},
+	}, nil
+}
+
 func (srv *Server) StreamSnapshots(req *pb.SnapshotRequest, stream grpc.ServerStreamingServer[pb.Snapshot]) error {
 	ch := srv.store.Subscribe()
 	defer srv.store.Unsubscribe(ch)

cmd/frontend/handler.go

@@ -76,6 +76,7 @@ type PageData struct {
 	Breadcrumbs    []Crumb
 	Windows        []Tab
 	GroupBys       []Tab
+	Targets        []Tab // source/target picker; empty when only one target available
 	RefreshSecs    int
 	Error          string
 	FilterExpr     string // current filter serialised to mini-language for the input box
@@ -340,6 +341,38 @@ func buildGroupByTabs(p QueryParams) []Tab {
 	return tabs
 }
 
+// buildTargetTabs builds the source/target picker tabs from a ListTargets response.
+// Returns nil (hide picker) when only one endpoint is reachable.
+func (h *Handler) buildTargetTabs(p QueryParams, lt *pb.ListTargetsResponse) []Tab {
+	// "all" always points at the configured aggregator default.
+	allTab := Tab{
+		Label:  "all",
+		URL:    p.buildURL(map[string]string{"target": h.defaultTarget}),
+		Active: p.Target == h.defaultTarget,
+	}
+
+	var collectorTabs []Tab
+	if lt != nil {
+		for _, t := range lt.Targets {
+			addr := t.Addr
+			if addr == "" {
+				addr = p.Target // collector reporting itself; addr is the current target
+			}
+			collectorTabs = append(collectorTabs, Tab{
+				Label:  t.Name,
+				URL:    p.buildURL(map[string]string{"target": addr}),
+				Active: p.Target == addr,
+			})
+		}
+	}
+
+	// Only render the picker when there is more than one choice.
+	if len(collectorTabs) == 0 {
+		return nil
+	}
+	return append([]Tab{allTab}, collectorTabs...)
+}
+
 func buildTableRows(entries []*pb.TopNEntry, p QueryParams) ([]TableRow, int64) {
 	if len(entries) == 0 {
 		return nil, 0
@@ -410,6 +443,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 	topNCh := make(chan topNResult, 1)
 	trendCh := make(chan trendResult, 1)
+	ltCh := make(chan *pb.ListTargetsResponse, 1)
 
 	go func() {
 		resp, err := client.TopN(ctx, &pb.TopNRequest{
@@ -427,9 +461,18 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		})
 		trendCh <- trendResult{resp, err}
 	}()
+	go func() {
+		resp, err := client.ListTargets(ctx, &pb.ListTargetsRequest{})
+		if err != nil {
+			ltCh <- nil
+		} else {
+			ltCh <- resp
+		}
+	}()
 
 	tn := <-topNCh
 	tr := <-trendCh
+	lt := <-ltCh
 
 	if tn.err != nil {
 		h.render(w, http.StatusBadGateway, h.errorPage(params,
@@ -459,6 +502,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		Breadcrumbs:    buildCrumbs(params),
 		Windows:        buildWindowTabs(params),
 		GroupBys:       buildGroupByTabs(params),
+		Targets:        h.buildTargetTabs(params, lt),
 		RefreshSecs:    h.refreshSecs,
 		FilterExpr:     filterExprInput,
 		FilterErr:      filterErr,

cmd/frontend/templates/base.html

@@ -34,6 +34,8 @@ a:hover { text-decoration: underline; }
 .error { color: #c00; border: 1px solid #fbb; background: #fff5f5; padding: 0.7em 1em; margin: 1em 0; border-radius: 3px; }
 .nodata { color: #999; margin: 2em 0; font-style: italic; }
 footer { margin-top: 2em; padding-top: 0.6em; border-top: 1px solid #e0e0e0; font-size: 0.8em; color: #999; }
+.tabs-targets { margin-top: -0.4em; }
+.tabs-label { font-size: 0.85em; color: #888; margin-right: 0.2em; align-self: center; }
 .filter-form { display: flex; gap: 0.4em; align-items: center; margin-bottom: 0.7em; }
 .filter-input { flex: 1; font-family: monospace; font-size: 13px; padding: 0.25em 0.5em; border: 1px solid #aaa; }
 .filter-form button { padding: 0.25em 0.8em; border: 1px solid #aaa; background: #f4f4f4; cursor: pointer; font-family: monospace; }

cmd/frontend/templates/index.html

@@ -13,6 +13,13 @@
 {{- end}}
 </div>
 
+{{if .Targets}}<div class="tabs tabs-targets">
+  <span class="tabs-label">source:</span>
+{{- range .Targets}}
+  <a href="{{.URL}}"{{if .Active}} class="active"{{end}}>{{.Label}}</a>
+{{- end}}
+</div>{{end}}
+
 <form class="filter-form" method="get" action="/">
   <input type="hidden" name="target" value="{{.Params.Target}}">
   <input type="hidden" name="w" value="{{.Params.WindowS}}">

docs/USERGUIDE.md

@@ -324,6 +324,12 @@ endpoint for that request (useful for comparing a single collector against the a
 http://frontend:8080/?target=nginx3:9090&w=5m
 ```
 
+**Source picker** — when the frontend is pointed at an aggregator, a `source:` tab row appears
+below the dimension tabs listing each individual collector alongside an **all** tab (the default
+merged view). Clicking a collector tab switches the frontend to query that collector directly for
+the current request, letting you answer "which nginx machine is the busiest?" without leaving the
+dashboard. The picker is hidden when querying a collector directly (it has no sub-sources to list).
+
 ---
 
 ## CLI
@@ -338,6 +344,7 @@ Default output is a human-readable table; add `--json` for machine-readable NDJS
 logtail-cli topn    [flags]   ranked label → count table
 logtail-cli trend   [flags]   per-bucket time series
 logtail-cli stream  [flags]   live snapshot feed (runs until Ctrl-C)
+logtail-cli targets [flags]   list targets known to the queried endpoint
 ```
 
 ### Shared flags (all subcommands)
@@ -397,6 +404,32 @@ RANK  COUNT    LABEL
 {"ts":1773516180,"source":"col-1","target":"nginx1:9090","total_entries":823,"top_label":"example.com","top_count":10000}
 ```
 
+### `targets` subcommand
+
+Lists the targets (collectors) known to the queried endpoint. When querying an aggregator, returns
+all configured collectors with their display names and addresses. When querying a collector,
+returns the collector itself (address shown as `(self)`).
+
+```bash
+# List collectors behind the aggregator
+logtail-cli targets --target agg:9091
+
+# Machine-readable output
+logtail-cli targets --target agg:9091 --json
+```
+
+Table output example:
+```
+nginx1.prod                              nginx1:9090
+nginx2.prod                              nginx2:9090
+nginx3.prod                              (self)
+```
+
+JSON output (`--json`) — one object per target:
+```json
+{"query_target":"agg:9091","name":"nginx1.prod","addr":"nginx1:9090"}
+```
+
 ### Examples
 
 ```bash

proto/logtail.proto

@@ -89,8 +89,23 @@ message Snapshot {
   repeated TopNEntry entries   = 3; // top-50K for this 1-minute bucket, sorted desc
 }
 
+// ListTargets — returns the targets this node knows about.
+// The aggregator returns all configured collectors; a collector returns itself.
+
+message ListTargetsRequest {}
+
+message TargetInfo {
+  string name = 1;  // display name (the --source value of the collector)
+  string addr = 2;  // gRPC address to use as target=; empty means "this endpoint"
+}
+
+message ListTargetsResponse {
+  repeated TargetInfo targets = 1;
+}
+
 service LogtailService {
   rpc TopN            (TopNRequest)         returns (TopNResponse);
   rpc Trend           (TrendRequest)        returns (TrendResponse);
   rpc StreamSnapshots (SnapshotRequest)     returns (stream Snapshot);
+  rpc ListTargets     (ListTargetsRequest)  returns (ListTargetsResponse);
 }

proto/logtailpb/logtail.pb.go

@@ -709,6 +709,138 @@ func (x *Snapshot) GetEntries() []*TopNEntry {
 	return nil
 }
 
+type ListTargetsRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListTargetsRequest) Reset() {
+	*x = ListTargetsRequest{}
+	mi := &file_logtail_proto_msgTypes[9]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListTargetsRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListTargetsRequest) ProtoMessage() {}
+
+func (x *ListTargetsRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_logtail_proto_msgTypes[9]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListTargetsRequest.ProtoReflect.Descriptor instead.
+func (*ListTargetsRequest) Descriptor() ([]byte, []int) {
+	return file_logtail_proto_rawDescGZIP(), []int{9}
+}
+
+type TargetInfo struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Name          string                 `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"` // display name (the --source value of the collector)
+	Addr          string                 `protobuf:"bytes,2,opt,name=addr,proto3" json:"addr,omitempty"` // gRPC address to use as target=; empty means "this endpoint"
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *TargetInfo) Reset() {
+	*x = TargetInfo{}
+	mi := &file_logtail_proto_msgTypes[10]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *TargetInfo) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*TargetInfo) ProtoMessage() {}
+
+func (x *TargetInfo) ProtoReflect() protoreflect.Message {
+	mi := &file_logtail_proto_msgTypes[10]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use TargetInfo.ProtoReflect.Descriptor instead.
+func (*TargetInfo) Descriptor() ([]byte, []int) {
+	return file_logtail_proto_rawDescGZIP(), []int{10}
+}
+
+func (x *TargetInfo) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
+func (x *TargetInfo) GetAddr() string {
+	if x != nil {
+		return x.Addr
+	}
+	return ""
+}
+
+type ListTargetsResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Targets       []*TargetInfo          `protobuf:"bytes,1,rep,name=targets,proto3" json:"targets,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListTargetsResponse) Reset() {
+	*x = ListTargetsResponse{}
+	mi := &file_logtail_proto_msgTypes[11]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListTargetsResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListTargetsResponse) ProtoMessage() {}
+
+func (x *ListTargetsResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_logtail_proto_msgTypes[11]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListTargetsResponse.ProtoReflect.Descriptor instead.
+func (*ListTargetsResponse) Descriptor() ([]byte, []int) {
+	return file_logtail_proto_rawDescGZIP(), []int{11}
+}
+
+func (x *ListTargetsResponse) GetTargets() []*TargetInfo {
+	if x != nil {
+		return x.Targets
+	}
+	return nil
+}
+
 var File_logtail_proto protoreflect.FileDescriptor
 
 const file_logtail_proto_rawDesc = "" +
@@ -755,7 +887,14 @@ const file_logtail_proto_rawDesc = "" +
 	"\bSnapshot\x12\x16\n" +
 	"\x06source\x18\x01 \x01(\tR\x06source\x12\x1c\n" +
 	"\ttimestamp\x18\x02 \x01(\x03R\ttimestamp\x12,\n" +
-	"\aentries\x18\x03 \x03(\v2\x12.logtail.TopNEntryR\aentries*:\n" +
+	"\aentries\x18\x03 \x03(\v2\x12.logtail.TopNEntryR\aentries\"\x14\n" +
+	"\x12ListTargetsRequest\"4\n" +
+	"\n" +
+	"TargetInfo\x12\x12\n" +
+	"\x04name\x18\x01 \x01(\tR\x04name\x12\x12\n" +
+	"\x04addr\x18\x02 \x01(\tR\x04addr\"D\n" +
+	"\x13ListTargetsResponse\x12-\n" +
+	"\atargets\x18\x01 \x03(\v2\x13.logtail.TargetInfoR\atargets*:\n" +
 	"\bStatusOp\x12\x06\n" +
 	"\x02EQ\x10\x00\x12\x06\n" +
 	"\x02NE\x10\x01\x12\x06\n" +
@@ -774,11 +913,12 @@ const file_logtail_proto_rawDesc = "" +
 	"\x04W15M\x10\x02\x12\b\n" +
 	"\x04W60M\x10\x03\x12\a\n" +
 	"\x03W6H\x10\x04\x12\b\n" +
-	"\x04W24H\x10\x052\xbf\x01\n" +
+	"\x04W24H\x10\x052\x89\x02\n" +
 	"\x0eLogtailService\x123\n" +
 	"\x04TopN\x12\x14.logtail.TopNRequest\x1a\x15.logtail.TopNResponse\x126\n" +
 	"\x05Trend\x12\x15.logtail.TrendRequest\x1a\x16.logtail.TrendResponse\x12@\n" +
-	"\x0fStreamSnapshots\x12\x18.logtail.SnapshotRequest\x1a\x11.logtail.Snapshot0\x01B0Z.git.ipng.ch/ipng/nginx-logtail/proto/logtailpbb\x06proto3"
+	"\x0fStreamSnapshots\x12\x18.logtail.SnapshotRequest\x1a\x11.logtail.Snapshot0\x01\x12H\n" +
+	"\vListTargets\x12\x1b.logtail.ListTargetsRequest\x1a\x1c.logtail.ListTargetsResponseB0Z.git.ipng.ch/ipng/nginx-logtail/proto/logtailpbb\x06proto3"
 
 var (
 	file_logtail_proto_rawDescOnce sync.Once
@@ -793,7 +933,7 @@ func file_logtail_proto_rawDescGZIP() []byte {
 }
 
 var file_logtail_proto_enumTypes = make([]protoimpl.EnumInfo, 3)
-var file_logtail_proto_msgTypes = make([]protoimpl.MessageInfo, 9)
+var file_logtail_proto_msgTypes = make([]protoimpl.MessageInfo, 12)
 var file_logtail_proto_goTypes = []any{
 	(StatusOp)(0),               // 0: logtail.StatusOp
 	(GroupBy)(0),                // 1: logtail.GroupBy
@@ -807,6 +947,9 @@ var file_logtail_proto_goTypes = []any{
 	(*TrendResponse)(nil),       // 9: logtail.TrendResponse
 	(*SnapshotRequest)(nil),     // 10: logtail.SnapshotRequest
 	(*Snapshot)(nil),            // 11: logtail.Snapshot
+	(*ListTargetsRequest)(nil),  // 12: logtail.ListTargetsRequest
+	(*TargetInfo)(nil),          // 13: logtail.TargetInfo
+	(*ListTargetsResponse)(nil), // 14: logtail.ListTargetsResponse
 }
 var file_logtail_proto_depIdxs = []int32{
 	0,  // 0: logtail.Filter.status_op:type_name -> logtail.StatusOp
@@ -818,17 +961,20 @@ var file_logtail_proto_depIdxs = []int32{
 	2,  // 6: logtail.TrendRequest.window:type_name -> logtail.Window
 	8,  // 7: logtail.TrendResponse.points:type_name -> logtail.TrendPoint
 	5,  // 8: logtail.Snapshot.entries:type_name -> logtail.TopNEntry
-	4,  // 9: logtail.LogtailService.TopN:input_type -> logtail.TopNRequest
+	13, // 9: logtail.ListTargetsResponse.targets:type_name -> logtail.TargetInfo
-	7,  // 10: logtail.LogtailService.Trend:input_type -> logtail.TrendRequest
+	4,  // 10: logtail.LogtailService.TopN:input_type -> logtail.TopNRequest
-	10, // 11: logtail.LogtailService.StreamSnapshots:input_type -> logtail.SnapshotRequest
+	7,  // 11: logtail.LogtailService.Trend:input_type -> logtail.TrendRequest
-	6,  // 12: logtail.LogtailService.TopN:output_type -> logtail.TopNResponse
+	10, // 12: logtail.LogtailService.StreamSnapshots:input_type -> logtail.SnapshotRequest
-	9,  // 13: logtail.LogtailService.Trend:output_type -> logtail.TrendResponse
+	12, // 13: logtail.LogtailService.ListTargets:input_type -> logtail.ListTargetsRequest
-	11, // 14: logtail.LogtailService.StreamSnapshots:output_type -> logtail.Snapshot
+	6,  // 14: logtail.LogtailService.TopN:output_type -> logtail.TopNResponse
-	12, // [12:15] is the sub-list for method output_type
+	9,  // 15: logtail.LogtailService.Trend:output_type -> logtail.TrendResponse
-	9,  // [9:12] is the sub-list for method input_type
+	11, // 16: logtail.LogtailService.StreamSnapshots:output_type -> logtail.Snapshot
-	9,  // [9:9] is the sub-list for extension type_name
+	14, // 17: logtail.LogtailService.ListTargets:output_type -> logtail.ListTargetsResponse
-	9,  // [9:9] is the sub-list for extension extendee
+	14, // [14:18] is the sub-list for method output_type
-	0,  // [0:9] is the sub-list for field type_name
+	10, // [10:14] is the sub-list for method input_type
+	10, // [10:10] is the sub-list for extension type_name
+	10, // [10:10] is the sub-list for extension extendee
+	0,  // [0:10] is the sub-list for field type_name
 }
 
 func init() { file_logtail_proto_init() }
@@ -843,7 +989,7 @@ func file_logtail_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_logtail_proto_rawDesc), len(file_logtail_proto_rawDesc)),
 			NumEnums:      3,
-			NumMessages:   9,
+			NumMessages:   12,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

proto/logtailpb/logtail_grpc.pb.go

@@ -22,6 +22,7 @@ const (
 	LogtailService_TopN_FullMethodName            = "/logtail.LogtailService/TopN"
 	LogtailService_Trend_FullMethodName           = "/logtail.LogtailService/Trend"
 	LogtailService_StreamSnapshots_FullMethodName = "/logtail.LogtailService/StreamSnapshots"
+	LogtailService_ListTargets_FullMethodName     = "/logtail.LogtailService/ListTargets"
 )
 
 // LogtailServiceClient is the client API for LogtailService service.
@@ -31,6 +32,7 @@ type LogtailServiceClient interface {
 	TopN(ctx context.Context, in *TopNRequest, opts ...grpc.CallOption) (*TopNResponse, error)
 	Trend(ctx context.Context, in *TrendRequest, opts ...grpc.CallOption) (*TrendResponse, error)
 	StreamSnapshots(ctx context.Context, in *SnapshotRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[Snapshot], error)
+	ListTargets(ctx context.Context, in *ListTargetsRequest, opts ...grpc.CallOption) (*ListTargetsResponse, error)
 }
 
 type logtailServiceClient struct {
@@ -80,6 +82,16 @@ func (c *logtailServiceClient) StreamSnapshots(ctx context.Context, in *Snapshot
 // This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
 type LogtailService_StreamSnapshotsClient = grpc.ServerStreamingClient[Snapshot]
 
+func (c *logtailServiceClient) ListTargets(ctx context.Context, in *ListTargetsRequest, opts ...grpc.CallOption) (*ListTargetsResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ListTargetsResponse)
+	err := c.cc.Invoke(ctx, LogtailService_ListTargets_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // LogtailServiceServer is the server API for LogtailService service.
 // All implementations must embed UnimplementedLogtailServiceServer
 // for forward compatibility.
@@ -87,6 +99,7 @@ type LogtailServiceServer interface {
 	TopN(context.Context, *TopNRequest) (*TopNResponse, error)
 	Trend(context.Context, *TrendRequest) (*TrendResponse, error)
 	StreamSnapshots(*SnapshotRequest, grpc.ServerStreamingServer[Snapshot]) error
+	ListTargets(context.Context, *ListTargetsRequest) (*ListTargetsResponse, error)
 	mustEmbedUnimplementedLogtailServiceServer()
 }
 
@@ -106,6 +119,9 @@ func (UnimplementedLogtailServiceServer) Trend(context.Context, *TrendRequest) (
 func (UnimplementedLogtailServiceServer) StreamSnapshots(*SnapshotRequest, grpc.ServerStreamingServer[Snapshot]) error {
 	return status.Error(codes.Unimplemented, "method StreamSnapshots not implemented")
 }
+func (UnimplementedLogtailServiceServer) ListTargets(context.Context, *ListTargetsRequest) (*ListTargetsResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ListTargets not implemented")
+}
 func (UnimplementedLogtailServiceServer) mustEmbedUnimplementedLogtailServiceServer() {}
 func (UnimplementedLogtailServiceServer) testEmbeddedByValue()                        {}
 
@@ -174,6 +190,24 @@ func _LogtailService_StreamSnapshots_Handler(srv interface{}, stream grpc.Server
 // This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
 type LogtailService_StreamSnapshotsServer = grpc.ServerStreamingServer[Snapshot]
 
+func _LogtailService_ListTargets_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ListTargetsRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(LogtailServiceServer).ListTargets(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: LogtailService_ListTargets_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(LogtailServiceServer).ListTargets(ctx, req.(*ListTargetsRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // LogtailService_ServiceDesc is the grpc.ServiceDesc for LogtailService service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -189,6 +223,10 @@ var LogtailService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "Trend",
 			Handler:    _LogtailService_Trend_Handler,
 		},
+		{
+			MethodName: "ListTargets",
+			Handler:    _LogtailService_ListTargets_Handler,
+		},
 	},
 	Streams: []grpc.StreamDesc{
 		{