[DO-NOT-MERGE] cmd/pkgsite: implement socket based activation

1 files changed, 19 insertions, 1 deletions

diff --git a/cmd/pkgsite/main.go b/cmd/pkgsite/main.go
index 49b99a59..eae690e0 100644
--- a/cmd/pkgsite/main.go
+++ b/cmd/pkgsite/main.go
@@ -60,6 +60,7 @@ import (
 	"strings"
 	"time"
 
+	"git.sr.ht/~shulhan/pakakeh.go/lib/systemd"
 	"golang.org/x/pkgsite/cmd/internal/pkgsite"
 	"golang.org/x/pkgsite/internal/browser"
 	"golang.org/x/pkgsite/internal/log"
@@ -133,10 +134,27 @@ func main() {
 		addr = ":http"
 	}
 
-	ln, err := net.Listen("tcp", addr)
+	var ln net.Listener
+	listeners, err := systemd.Listeners(true)
 	if err != nil {
 		dief("%s", err)
 	}
+	if len(listeners) > 1 {
+		dief(`too many listeners received for activation`)
+	}
+	if len(listeners) == 1 {
+		ln = listeners[0]
+		gotAddr := ln.Addr().String()
+		if gotAddr != addr {
+			dief(`invalid Listener address, got %s, want %s`,
+				gotAddr, addr)
+		}
+	} else {
+		ln, err = net.Listen("tcp", addr)
+		if err != nil {
+			dief("%s", err)
+		}
+	}
 
 	url := "http://" + addr
 	log.Infof(ctx, "Listening on addr %s", url)