add option for custom papertrail hostname (#4912)

app.ts

@@ -94,6 +94,7 @@ const opts = nopt({
     ensureNoIdClash: [Boolean],
     logHost: [String],
     logPort: [Number],
+    hostnameForLogging: [String],
     suppressConsoleLog: [Boolean],
     metricsPort: [Number],
     loki: [String],
@@ -172,7 +173,7 @@ const defArgs = {
 };
 
 if (opts.logHost && opts.logPort) {
-    logToPapertrail(opts.logHost, opts.logPort, defArgs.env.join('.'));
+    logToPapertrail(opts.logHost, opts.logPort, defArgs.env.join('.'), opts.hostnameForLogging);
 }
 
 if (opts.loki) {

lib/logger.ts

@@ -55,22 +55,35 @@ export function makeLogStream(level: string, logger_: winston.Logger = logger):
     });
 }
 
+type MyPapertrailTransportOptions = TransportStreamOptions & {
+    host: string;
+    port: number;
+    identifier: string;
+    hostnameForLogging?: string;
+};
+
 // Our own transport which uses Papertrail under the hood but better adapts it to work in winston 3.0
 class MyPapertrailTransport extends TransportStream {
     private readonly hostname: string;
     private readonly program: string;
     public readonly transport: Papertrail;
 
-    constructor(opts: TransportStreamOptions & {host: string; port: number; identifier: string}) {
+    constructor(opts: MyPapertrailTransportOptions) {
         super(opts);
 
-        this.hostname = os.hostname();
         this.program = opts.identifier;
 
+        if (opts.hostnameForLogging) {
+            this.hostname = opts.hostnameForLogging;
+        } else {
+            this.hostname = os.hostname();
+        }
+
         this.transport = new Papertrail({
             host: opts.host,
             port: opts.port,
             logFormat: (level, message) => message,
+            hostname: this.hostname,
         });
     }
 
@@ -102,12 +115,15 @@ export function logToLoki(url) {
     logger.info('Configured loki');
 }
 
-export function logToPapertrail(host: string, port: number, identifier: string) {
-    const transport = new MyPapertrailTransport({
+export function logToPapertrail(host: string, port: number, identifier: string, hostnameForLogging?: string) {
+    const settings: MyPapertrailTransportOptions = {
         host: host,
         port: port,
         identifier: identifier,
-    });
+        hostnameForLogging,
+    };
+
+    const transport = new MyPapertrailTransport(settings);
     transport.transport.on('error', err => {
         logger.error(err);
     });