syncthing: Add discovery/relay servers, improve build (#34831)

- Fix GOPATH checks
- Install manpages
- Also build and install discovery and relay servers + cli 
- Make the build more pure by explicitly setting the build username/host

pkgs/applications/networking/syncthing/add-stcli-target.patch

@@ -0,0 +1,17 @@
+diff --git i/build.go w/build.go
+index 7d400d6f..1b5e1d25 100644
+--- i/build.go
++++ w/build.go
+@@ -175,6 +175,12 @@ var targets = map[string]target{
+ 			{src: "AUTHORS", dst: "deb/usr/share/doc/syncthing-relaypoolsrv/AUTHORS.txt", perm: 0644},
+ 		},
+ 	},
++	"stcli": {
++		name:        "stcli",
++		description: "Syncthing CLI",
++		buildPkg:    "github.com/syncthing/syncthing/cmd/stcli",
++		binaryName:  "stcli", // .exe will be added automatically for Windows builds
++	},
+ }
+ 
+ func init() {

pkgs/applications/networking/syncthing/default.nix

@@ -1,8 +1,10 @@
-{ stdenv, lib, fetchFromGitHub, go, procps, removeReferencesTo }:
+{ stdenv, lib, go, procps, removeReferencesTo, fetchFromGitHub }:
 
+let
+  common = { stname, target, patches ? [], postInstall ? "" }:
     stdenv.mkDerivation rec {
       version = "0.14.44";
-  name = "syncthing-${version}";
+      name = "${stname}-${version}";
 
       src = fetchFromGitHub {
         owner  = "syncthing";
@@ -11,25 +13,55 @@ stdenv.mkDerivation rec {
         sha256 = "1gdkx6lbzmdz2hqc9slbq41rwgkxmdisnj0iywx4mppmc2b4v6wh";
       };
 
-  buildInputs = [ go removeReferencesTo ];
+      inherit patches;
+
+      buildInputs = [ go ];
+      nativeBuildInputs = [ removeReferencesTo ];
 
       buildPhase = ''
-    mkdir -p src/github.com/syncthing
+        # Syncthing expects that it is checked out in $GOPATH, if that variable is
-    ln -s $(pwd) src/github.com/syncthing/syncthing
+        # set.  Since this isn't true when we're fetching source, we can explicitly
-    export GOPATH=$(pwd)
+        # unset it and force Syncthing to set up a temporary one for us.
-
+        env GOPATH= BUILD_USER=nix BUILD_HOST=nix go run build.go -no-upgrade -version v${version} build ${target}
-    # Syncthing's build.go script expects this working directory
-    cd src/github.com/syncthing/syncthing
-
-    go run build.go -no-upgrade -version v${version} build
       '';
 
       installPhase = ''
-    mkdir -p $out/lib/systemd/{system,user}
+        install -Dm755 ${target} $out/bin/${target}
+        runHook postInstall
+      '';
 
-    install -Dm755 syncthing $out/bin/syncthing
+      inherit postInstall;
+
+      preFixup = ''
+        find $out/bin -type f -exec remove-references-to -t ${go} '{}' '+'
+      '';
+
+      meta = with lib; {
+        homepage = https://www.syncthing.net/;
+        description = "Open Source Continuous File Synchronization";
+        license = licenses.mpl20;
+        maintainers = with maintainers; [ pshendry joko peterhoeg andrew-d ];
+        platforms = platforms.unix;
+      };
+    };
+
+in {
+  syncthing = common {
+    stname = "syncthing";
+    target = "syncthing";
+
+    postInstall = ''
+      # This installs man pages in the correct directory according to the suffix
+      # on the filename
+      for mf in man/*.[1-9]; do
+        mantype="$(echo "$mf" | awk -F"." '{print $NF}')"
+        mandir="$out/share/man/man$mantype"
+        install -Dm644 "$mf" "$mandir/$(basename "$mf")"
+      done
 
     '' + lib.optionalString (stdenv.isLinux) ''
+      mkdir -p $out/lib/systemd/{system,user}
+
       substitute etc/linux-systemd/system/syncthing-resume.service \
                  $out/lib/systemd/system/syncthing-resume.service \
                  --replace /usr/bin/pkill ${procps}/bin/pkill
@@ -42,16 +74,30 @@ stdenv.mkDerivation rec {
                  $out/lib/systemd/user/syncthing.service \
                  --replace /usr/bin/syncthing $out/bin/syncthing
     '';
+  };
 
-  preFixup = ''
+  syncthing-cli = common {
-    find $out/bin -type f -exec remove-references-to -t ${go} '{}' '+'
+    stname = "syncthing-cli";
+
+    patches = [ ./add-stcli-target.patch ];
+    target = "stcli";
+  };
+
+  syncthing-discovery = common {
+    stname = "syncthing-discovery";
+    target = "stdiscosrv";
+  };
+
+  syncthing-relay = common {
+    stname = "syncthing-relay";
+    target = "strelaysrv";
+
+    postInstall = lib.optionalString (stdenv.isLinux) ''
+      mkdir -p $out/lib/systemd/system
+
+      substitute cmd/strelaysrv/etc/linux-systemd/strelaysrv.service \
+                 $out/lib/systemd/system/strelaysrv.service \
+                 --replace /usr/bin/strelaysrv $out/bin/strelaysrv
     '';
-
-  meta = with stdenv.lib; {
-    homepage = https://www.syncthing.net/;
-    description = "Open Source Continuous File Synchronization";
-    license = licenses.mpl20;
-    maintainers = with maintainers; [ pshendry joko peterhoeg ];
-    platforms = platforms.unix;
   };
 }

pkgs/top-level/all-packages.nix

@@ -17352,7 +17352,11 @@ with pkgs;
 
   syncplay = callPackage ../applications/networking/syncplay { };
 
-  syncthing = callPackage ../applications/networking/syncthing { };
+  inherit (callPackages ../applications/networking/syncthing { })
+    syncthing
+    syncthing-cli
+    syncthing-discovery
+    syncthing-relay;
 
   syncthing-gtk = python2Packages.callPackage ../applications/networking/syncthing-gtk { };