add process discovery for linux

Author: Xetera

.dockerignore

@@ -0,0 +1,16 @@
+.git
+.gitignore
+.github
+.devenv
+devenv.nix
+devenv.yaml
+devenv.lock
+.envrc
+.zed
+.claude
+README.md
+showcase.jpg
+bin/
+localproxyd
+*.md
+!README.md

Dockerfile

@@ -0,0 +1,24 @@
+FROM golang:1.25-alpine AS builder
+
+RUN apk add --no-cache git ca-certificates
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+RUN CGO_ENABLED=0 GOOS=linux go build -o localproxyd ./cmd/localproxyd
+
+FROM alpine:latest
+
+RUN apk --no-cache add ca-certificates netcat-openbsd
+
+WORKDIR /root
+
+COPY --from=builder /app/localproxyd /usr/local/bin/
+
+COPY --from=builder /app/internal/dashboard/templates /root/internal/dashboard/templates
+
+CMD sh -c "while true; do nc -l -p 9999; done & localproxyd --watch /"

internal/dashboard/templates/dashboard.html

@@ -577,7 +577,7 @@ <h1>LocalProxy</h1>
               https://{{if
               .SelectedBackend.Subdomain}}{{.SelectedBackend.Subdomain}}.{{end}}localhost
             </a>
-            <div class="metrics-grid">
+            <!--<div class="metrics-grid">
               <div class="metric-card">
                 <div class="metric-label">Traffic</div>
                 <div class="metric-value">
@@ -654,7 +654,7 @@ <h1>LocalProxy</h1>
                   <span class="metric-unit">disconnects</span>
                 </div>
               </div>
-            </div>
+            </div>-->
             <div class="info-grid">
               <div class="info-item">
                 <span class="info-label">PID:</span>
@@ -698,7 +698,8 @@ <h1>LocalProxy</h1>
                   class="port-item{{if eq .Port (port $.SelectedBackend.Endpoint)}} active{{end}}"
                 >
                   <span class="port-arrow"
-                    >{{if eq .Port (port $.SelectedBackend.Endpoint)}}&gt;{{end}}</span
+                    >{{if eq .Port (port
+                    $.SelectedBackend.Endpoint)}}&gt;{{end}}</span
                   >
                   <span>:{{.Text}}</span>
                   <span class="port-protocol">{{or .Protocol "?"}}</span>
@@ -715,8 +716,8 @@ <h1>LocalProxy</h1>
               >
                 <div class="logs-container">
                   <!-- Debug: Source = "{{.SelectedBackend.Source}}" -->
-                  {{if and .SelectedBackend (eq .SelectedBackend.Source "process")
-                  (not $.TraceProcessLogs)}}
+                  {{if and .SelectedBackend (eq .SelectedBackend.Source
+                  "process") (not $.TraceProcessLogs)}}
                   <div class="log-disclaimer">
                     <p>
                       Logs for processes are disabled. To enable them, run

internal/discovery/process.go

@@ -161,6 +161,7 @@ func (w *ProcessWatcher) scan() ([]DiscoveredService, error) {
 		log.Printf("process: getListeningPorts error: %v", err)
 		return nil, err
 	}
+	log.Printf("process: scanning %d listeners", len(listeners))
 
 	state := &scanState{
 		ignoredDirs: map[string]bool{"apps": true, "packages": true},
@@ -170,9 +171,11 @@ func (w *ProcessWatcher) scan() ([]DiscoveredService, error) {
 	}
 
 	for _, entry := range listeners {
+		log.Printf("process: processing PID=%d port=%d", entry.PID, entry.Endpoint.Port())
 		w.processEntry(state, entry)
 	}
 
+	log.Printf("process: scan complete, found %d results", len(state.results))
 	return state.results, nil
 }
 
@@ -188,19 +191,24 @@ func (w *ProcessWatcher) processEntry(state *scanState, entry portEntry) {
 	pid := entry.PID
 
 	cwd := w.getOrCacheCWD(state, pid)
+	log.Printf("process: PID=%d cwd='%s'", pid, cwd)
 
 	if cwd == "" {
+		log.Printf("process: PID=%d has no CWD, trying well-known", pid)
 		w.handleUnknownCWD(state, pid, entry.Endpoint)
 		return
 	}
 
 	basePath := w.findMatchingBasePath(cwd)
+	log.Printf("process: PID=%d basePath='%s', basePaths=%v", pid, basePath, w.basePaths)
 	if basePath == "" {
+		log.Printf("process: PID=%d outside base paths, trying well-known", pid)
 		w.handleOutsideBasePath(state, pid, entry.Endpoint)
 		return
 	}
 
 	result := w.buildSubdomain(basePath, cwd, state.ignoredDirs)
+	log.Printf("process: PID=%d subdomain='%s', needsCustomMapping=%v", pid, result.subdomain, result.needsCustomMapping)
 	if result.subdomain == "" && !result.needsCustomMapping {
 		return
 	}
@@ -231,8 +239,10 @@ func (w *ProcessWatcher) addWellKnownProcess(state *scanState, pid int, endpoint
 	port := endpoint.Port()
 	info, ok := WellKnownPorts[port]
 	if !ok || state.usedPorts[port] {
+		log.Printf("process: PID=%d port=%d not well-known or already used (ok=%v, used=%v)", pid, port, ok, state.usedPorts[port])
 		return
 	}
+	log.Printf("process: adding PID=%d as well-known service: %s", pid, info.Subdomain)
 	state.results = append(state.results, DiscoveredService{
 		Subdomain: info.Subdomain,
 		Endpoint:  endpoint,

internal/discovery/process_linux.go

@@ -20,12 +20,15 @@ func hexByte(s string) int {
 func (w *ProcessWatcher) getListeningPorts() ([]portEntry, error) {
 	entries, err := w.parseProcNet("/proc/net/tcp")
 	if err != nil {
+		fmt.Printf("Error parsing /proc/net/tcp: %v\n", err)
 		return nil, err
 	}
+	fmt.Printf("Found %d entries from /proc/net/tcp\n", len(entries))
 
 	entries6, err := w.parseProcNet("/proc/net/tcp6")
 	if err == nil {
 		entries = append(entries, entries6...)
+		fmt.Printf("Found %d entries from /proc/net/tcp6\n", len(entries6))
 	}
 
 	return entries, nil
@@ -40,6 +43,7 @@ func (w *ProcessWatcher) parseProcNet(path string) ([]portEntry, error) {
 
 	inodeToPID := make(map[string]int)
 	procDirs, _ := filepath.Glob("/proc/[0-9]*/fd/*")
+	fmt.Printf("Found %d fd paths\n", len(procDirs))
 	for _, fdPath := range procDirs {
 		link, err := os.Readlink(fdPath)
 		if err != nil {
@@ -59,6 +63,7 @@ func (w *ProcessWatcher) parseProcNet(path string) ([]portEntry, error) {
 		}
 		inodeToPID[inode] = pid
 	}
+	fmt.Printf("Mapped %d inodes to PIDs\n", len(inodeToPID))
 
 	var result []portEntry
 	scanner := bufio.NewScanner(file)
@@ -68,6 +73,7 @@ func (w *ProcessWatcher) parseProcNet(path string) ([]portEntry, error) {
 		line := scanner.Text()
 		fields := strings.Fields(line)
 		if len(fields) < 10 {
+			fmt.Printf("Skipping line with %d fields: %s\n", len(fields), line)
 			continue
 		}
 
@@ -79,18 +85,21 @@ func (w *ProcessWatcher) parseProcNet(path string) ([]portEntry, error) {
 		localAddr := fields[1]
 		addrParts := strings.Split(localAddr, ":")
 		if len(addrParts) != 2 {
+			fmt.Printf("Skipping bad address format: %s\n", localAddr)
 			continue
 		}
 
 		addrHex := addrParts[0]
 		portHex := addrParts[1]
 		port64, err := strconv.ParseInt(portHex, 16, 32)
 		if err != nil {
+			fmt.Printf("Skipping bad port %s: %v\n", portHex, err)
 			continue
 		}
 		port := int(port64)
 
 		if port < 1024 {
+			fmt.Printf("Skipping port < 1024: %d\n", port)
 			continue
 		}
 
@@ -108,11 +117,13 @@ func (w *ProcessWatcher) parseProcNet(path string) ([]portEntry, error) {
 		inode := fields[9]
 		pid, ok := inodeToPID[inode]
 		if !ok {
+			fmt.Printf("No PID for inode %s, port %d, ip %s\n", inode, port, ipStr)
 			continue
 		}
 
 		addr, err := netip.ParseAddr(ipStr)
 		if err != nil {
+			fmt.Printf("Skipping invalid IP %s: %v\n", ipStr, err)
 			continue
 		}
 		result = append(result, portEntry{PID: pid, Endpoint: netip.AddrPortFrom(addr, uint16(port))})

internal/proxy/protocol/postgres.go

@@ -10,9 +10,16 @@ import (
 	"github.com/jackc/pgx/v5/pgproto3"
 )
 
+type Direction int
+
+const (
+	DirectionClientToServer Direction = 0
+	DirectionServerToClient Direction = iota
+)
+
 type PgMessage struct {
 	Timestamp time.Time `json:"timestamp"`
-	Direction string    `json:"direction"`
+	Direction Direction `json:"direction"`
 	Type      string    `json:"type"`
 	Details   any       `json:"details,omitempty"`
 	Raw       []byte    `json:"-"`
@@ -50,7 +57,7 @@ func ParseFrontendMessage(endpoint netip.AddrPort, data []byte) *PgMessage {
 
 	msg := &PgMessage{
 		Timestamp: time.Now(),
-		Direction: "client->server",
+		Direction: DirectionClientToServer,
 		Raw:       data,
 	}
 
@@ -178,7 +185,7 @@ func ParseBackendMessage(endpoint netip.AddrPort, data []byte) *PgMessage {
 
 	msg := &PgMessage{
 		Timestamp: time.Now(),
-		Direction: "server->client",
+		Direction: DirectionServerToClient,
 		Raw:       data,
 	}