Re-add pidfilev3.1.0

Configurable via the `pidfile' config option.

* bin/server.js: Accept `pidfile' config.  Include path in greeting.
  (writePidFile): Write to `pidfile' and unlink after exit.
* conf/vanilla-server.json (pidfile): Add configuration key.

2 files changed, 18 insertions, 3 deletions

diff --git a/bin/server.js b/bin/server.js
index 6929fca..e44688c 100644
--- a/bin/server.js
+++ b/bin/server.js
@@ -47,13 +47,17 @@ ConfLoader( fs, ConfStore )
     .then( conf => Promise.all( [
         conf.get( 'name' ),
         conf.get( 'daemon' ),
+        conf.get( 'pidfile' ),
         Promise.resolve( conf ),
     ] ) )
-    .then( ([ name, daemon, conf ]) =>
+    .then( ([ name, daemon, pidfile, conf ]) =>
     {
         const daemon_path = conf_dir + '/' + daemon;
+        const pid_path    = conf_dir + '/' + ( pidfile || ".pid" );
+
+        writePidFile( pid_path );
+        greet( name, pid_path );
 
-        greet( name );
         return require( daemon_path )( conf ).start();
     } )
     .catch( e => {
@@ -62,8 +66,17 @@ ConfLoader( fs, ConfStore )
     } );
 
 
-function greet( name )
+function writePidFile( pid_path )
+{
+    fs.writeFile( pid_path, process.pid );
+
+    process.on( 'exit', () => fs.unlink( pid_path ) );
+}
+
+
+function greet( name, pid_path )
 {
     console.log( `${name} (liza-${version})`);
     console.log( `Server configuration: ${conf_path}` );
+    console.log( `PID file: ${pid_path}` );
 }
diff --git a/conf/vanilla-server.json b/conf/vanilla-server.json
index 14f7fc5..5e5da12 100644
--- a/conf/vanilla-server.json
+++ b/conf/vanilla-server.json
@@ -2,6 +2,8 @@
   "name":   "Liza Server",
   "daemon": "../src/server/daemon/DevDaemon",
 
+  "pidfile": "",
+
   "http": {
     "port": 8822
   },