Add stackdriver format to all streams

Author: Michal Vlasák

index.js

@@ -4,6 +4,7 @@ const multistream = require('pino-multi-stream').multistream;
 const serializers = require('./serializers');
 const { levels } = require('./levels');
 const { expressMiddleware, expressErrorMiddleware } = require('./express');
+const { StackDriverFormatStream } = require('./stackdriver');
 
 // This is a custom slightly edited version of pino-multistream's wirte method, whch adds support for maximum log level
 // The original version was pino-multistream 3.1.2 (commit 71d98ae) - https://github.com/pinojs/pino-multi-stream/blob/71d98ae191e02c56e39e849d2c30d59c8c6db1b9/multistream.js#L43
@@ -68,6 +69,15 @@ const defaultLogger = (options = {}) => {
             { level: levels.warn, stream: process.stderr },
         ];
     }
+    streams = streams.map(stream => {
+        const newStream = new StackDriverFormatStream();
+        newStream.pipe(stream.stream);
+        return {
+            level: stream.level,
+            maxLevel: stream.maxLevel,
+            stream: newStream,
+        };
+    });
 
     if (!options.ignoredHttpMethods) {
         options.ignoredHttpMethods = ['OPTIONS'];

stackdriver.js

@@ -0,0 +1,22 @@
+const { Transform } = require('stream');
+
+const PINO_TO_STACKDRIVER = {
+    10: 'DEBUG',
+    20: 'DEBUG',
+    30: 'INFO',
+    40: 'WARNING',
+    50: 'ERROR',
+    60: 'CRITICAL',
+};
+
+class StackDriverFormatStream extends Transform {
+    _transform(chunk, encoding, callback) {
+        const obj = JSON.parse(chunk);
+        obj.severity = PINO_TO_STACKDRIVER[obj.level] || 'UNKNOWN';
+
+        this.push(`${JSON.stringify(obj)}\n`);
+        callback();
+    }
+}
+
+module.exports = { StackDriverFormatStream };