From a9a437cee4fbd567c3d7f9423078e029e0efc812 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <hg@lukegb.com>
Date: Mon, 22 Mar 2021 02:41:59 +0000
Subject: [PATCH] fup: add systemd socket activation support to `fup serve`

---
 web/fup/cmd/serve.go | 11 +++++++++++
 web/fup/default.nix  |  2 +-
 web/fup/go.mod       |  1 +
 web/fup/go.sum       |  4 ++++
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/web/fup/cmd/serve.go b/web/fup/cmd/serve.go
index 48ba35475a..2ab5e5b7e3 100644
--- a/web/fup/cmd/serve.go
+++ b/web/fup/cmd/serve.go
@@ -12,6 +12,7 @@ import (
 	"os/exec"
 	"strings"
 
+	"github.com/coreos/go-systemd/v22/activation"
 	"github.com/google/safehtml"
 	"github.com/spf13/cobra"
 	"hg.lukegb.com/lukegb/depot/web/fup/fuphttp"
@@ -72,6 +73,16 @@ var (
 			http.Handle("/", a.Handler())
 			http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.FS(fupstatic.Static))))
 			log.Printf("Serving on %s", serveBind)
+			if serveBind == "systemd" {
+				listeners, err := activation.Listeners()
+				if err != nil {
+					return fmt.Errorf("getting systemd socket-activated listeners: %v", err)
+				}
+				if len(listeners) != 1 {
+					return fmt.Errorf("unexpected systemd socket activation fds: got %d; want 1", len(listeners))
+				}
+				return http.Serve(listeners[0], nil)
+			}
 			return http.ListenAndServe(serveBind, nil)
 		},
 	}
diff --git a/web/fup/default.nix b/web/fup/default.nix
index 84d23a991e..d74952cd46 100644
--- a/web/fup/default.nix
+++ b/web/fup/default.nix
@@ -21,7 +21,7 @@ pkgs.buildGoModule {
     wrapProgram $out/bin/fup --prefix PATH : ${lib.makeBinPath [ depot.third_party.cheddar ]}
   '';
 
-  vendorSha256 = "sha256:0myd1p61q777ybbwdz8k4nbchh2hv1yr8008061m3gc44s3gsphx";
+  vendorSha256 = "sha256:08v3n5lrnbdbs36qpr5brqrainb34nwgm9z2pbxwpj85fxb8ky06";
 
   meta = with pkgs.lib; {
     description = "Simple file upload manager.";
diff --git a/web/fup/go.mod b/web/fup/go.mod
index 72206823c9..89cb9f7102 100644
--- a/web/fup/go.mod
+++ b/web/fup/go.mod
@@ -7,6 +7,7 @@ module hg.lukegb.com/lukegb/depot/web/fup
 go 1.16
 
 require (
+	github.com/coreos/go-systemd/v22 v22.3.0
 	github.com/dustinkirkland/golang-petname v0.0.0-20191129215211-8e5a1ed0cff0
 	github.com/gabriel-vasile/mimetype v1.2.0
 	github.com/google/safehtml v0.0.2
diff --git a/web/fup/go.sum b/web/fup/go.sum
index 3e26e764e2..bf1b8e90d0 100644
--- a/web/fup/go.sum
+++ b/web/fup/go.sum
@@ -104,7 +104,10 @@ github.com/cncf/udpa/go v0.0.0-20200629203442-efcf912fb354/go.mod h1:WmhPx2Nbnht
 github.com/coreos/bbolt v1.3.2/go.mod h1:iRUV2dpdMOn7Bo10OQBFzIJO9kkE559Wcmn+qkEiiKk=
 github.com/coreos/etcd v3.3.13+incompatible/go.mod h1:uF7uidLiAD3TWHmW31ZFd/JWoc32PjwdhPthX9715RE=
 github.com/coreos/go-semver v0.3.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3EedlOD2RNk=
+github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e h1:Wf6HqHfScWJN9/ZjdUKyjop4mf3Qdd+1TvvltAvM3m8=
 github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
+github.com/coreos/go-systemd/v22 v22.3.0 h1:C8u/Ljj8G8O6rqWJh2J8cDyeEFBMWvXlvJ/ccMyzcqw=
+github.com/coreos/go-systemd/v22 v22.3.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+1atmu1JpKERPPk=
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -150,6 +153,7 @@ github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/me
 github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee/go.mod h1:L0fX3K22YWvt/FAX9NnzrNzcI4wNYi9Yku4O0LKYflo=
 github.com/gobwas/pool v0.2.0/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
 github.com/gobwas/ws v1.0.2/go.mod h1:szmBTxLgaFppYjEmNtny/v3w89xOydFnnZMcgRRu/EM=
+github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
 github.com/golang-sql/civil v0.0.0-20190719163853-cb61b32ac6fe/go.mod h1:8vg3r2VgvsThLBIFL93Qb5yWzgyZWhEmBwUJWevAkK0=