Adding filtering to the logger

- Closes elastic#5036
- Add `applyFilterToKey()`
- Add test for `applyFilterToKey()`
- Add `filter` attribute to config for reporters
- Add `this.filter` method to `LogFormat` class

src/server/logging/LogFormat.js

@@ -6,6 +6,7 @@ let ansicolors = require('ansicolors');
 let stringify = require('json-stringify-safe');
 let querystring = require('querystring');
 let inspect = require('util').inspect;
+let applyFilterToKey = require('./applyFilterToKey');
 
 function serializeError(err) {
   return {
@@ -24,16 +25,27 @@ let levelColor = function (code) {
   return ansicolors.red(code);
 };
 
+
 module.exports = class TransformObjStream extends Stream.Transform {
-  constructor() {
+  constructor(config) {
     super({
       readableObjectMode: false,
       writableObjectMode: true
     });
+    this.config = config;
+  }
+
+  filter(data) {
+    if (this.config.filter) {
+      _.each(this.config.filter, (action, key) => {
+        applyFilterToKey(data, key, action);
+      });
+    }
+    return data;
   }
 
   _transform(event, enc, next) {
-    var data = this.readEvent(event);
+    var data = this.filter(this.readEvent(event));
     this.push(this.format(data) + '\n');
     next();
   }

src/server/logging/LogReporter.js

@@ -8,7 +8,7 @@ let LogFormatString = require('./LogFormatString');
 module.exports = class KbnLogger {
   constructor(events, config) {
     this.squeeze = new Squeeze(events);
-    this.format = config.json ? new LogFormatJson() : new LogFormatString();
+    this.format = config.json ? new LogFormatJson(config) : new LogFormatString(config);
 
     if (config.dest === 'stdout') {
       this.dest = process.stdout;

src/server/logging/__tests__/applyFilterToKey.js

@@ -0,0 +1,49 @@
+var applyFilterToKey = require('../applyFilterToKey');
+var expect = require('expect.js');
+
+function fixture() {
+  return {
+    req: {
+      headers: {
+        authorization: 'Basic dskd939k2i'
+      }
+    }
+  };
+}
+
+describe('applyFilterToKey(obj, key, action)', function () {
+
+  it('should remove a key from an object recursivly', function () {
+    var data = fixture();
+    applyFilterToKey(data, 'authorization', 'remove');
+    expect(data).to.eql({
+      req: { headers: {} }
+    });
+  });
+
+  it('should censor a key in an object recursivly', function () {
+    var data = fixture();
+    applyFilterToKey(data, 'authorization', 'censor');
+    expect(data).to.eql({
+      req: {
+        headers: {
+          authorization: 'XXXXXXXXXXXXXXXX'
+        }
+      }
+    });
+  });
+
+  it('should censor key with a RegEx in an object recursivly', function () {
+    var data = fixture();
+    var regex = /([^\s]+)$/;
+    applyFilterToKey(data, 'authorization', regex);
+    expect(data).to.eql({
+      req: {
+        headers: {
+          authorization: 'Basic XXXXXXXXXX'
+        }
+      }
+    });
+  });
+
+});

src/server/logging/applyFilterToKey.js

@@ -0,0 +1,23 @@
+function replacer(match, group) {
+  return (new Array(group.length + 1).join('X'));
+}
+
+module.exports = function applyFilterToKey(obj, key, action) {
+  for (let k in obj)  {
+    if (obj.hasOwnProperty(k)) {
+      let val = obj[k];
+      if (typeof val === 'object') {
+        applyFilterToKey(val, key, action);
+      } else if (k === key) {
+        val = ''  + val;
+        if (action === 'remove') delete obj[k];
+        if (action === 'censor') {
+          obj[k] = val.replace(/./g, 'X');
+        };
+        if (action instanceof RegExp) {
+          obj[k] = val.replace(action, replacer);
+        }
+      }
+    }
+  }
+};

src/server/logging/index.js

@@ -42,7 +42,10 @@ module.exports = function (kbnServer, server, config) {
             reporter: require('./LogReporter'),
             config: {
               json: config.get('logging.json'),
-              dest: config.get('logging.dest')
+              dest: config.get('logging.dest'),
+              filter: {
+                authorization: 'remove'
+              }
             },
             events: _.transform(events, function (filtered, val, key) {
               // provide a string compatible way to remove events