Data sanitization

What happens by default

Before a log is queued, the SDK copies it and cleans the copy. It looks at the message, the data you attach, the context, and the metadata. Two things happen:

• text matching a known pattern, such as an email address, is replaced;
• fields whose names suggest secrets, such as password, are masked.

The error’s name, message and stack, the page address, the referrer and the user agent are not cleaned. See Privacy and PII redaction for the full picture.

Built-in patterns

The patterns are exported as PII_PATTERNS. They only look at text: a number stored as a number is left alone, but the same digits inside a string can match. In a string, a nine-digit order ID becomes [SSN_REDACTED] and a ten-digit Unix timestamp becomes [PHONE_REDACTED].

Field masking

Any field in the data, context or metadata whose name contains one of these words, ignoring case, has its string value masked: password, secret, token, key, ssn, email. The first and last characters are kept and the rest become asterisks; values of 4 characters or fewer become [ANONYMIZED].

logger.info('Signed in', { email: 'ada@example.com', apiKey: 'example-key-123', plan: 'pro' });
// Sent as: { email: '[**************]', apiKey: 'e*************3', plan: 'pro' }

The email value was first replaced by the email pattern, then masked because of its field name. Matching is by substring, so key also masks fields such as keyboardLayout or monkey.

Presets

BALANCED is what you get without configuring anything. Pick another with SANITIZATION_PRESETS:

import { Apperio, SANITIZATION_PRESETS } from 'apperio';

const logger = new Apperio({
  apiKey: 'your-api-key',
  projectId: 'your-project-id',
  sanitization: { config: SANITIZATION_PRESETS.STRICT },
});

Custom rules

Add a rule for data only your app has. Give the pattern the g flag, or only the first match in each string is replaced.

logger.addCustomSanitizationRule({
  pattern: /CUST-\d{6}/g,
  replacement: '[CUSTOMER_ID]',
  description: 'Customer number',
  severity: 'medium',
  category: 'custom',
});

logger.removeCustomSanitizationRule('Customer number'); // removed by description

The full configuration

sanitization.config takes a complete SanitizationConfig. The easiest way to change one part is to start from a preset:

import { Apperio, SANITIZATION_PRESETS } from 'apperio';

const logger = new Apperio({
  apiKey: 'your-api-key',
  projectId: 'your-project-id',
  sanitization: {
    config: {
      ...SANITIZATION_PRESETS.BALANCED,
      sensitiveFields: [...SANITIZATION_PRESETS.BALANCED.sensitiveFields, 'address'],
      customRules: [
        {
          pattern: /CUST-\d{6}/g,
          replacement: '[CUSTOMER_ID]',
          description: 'Customer number',
          severity: 'medium',
          category: 'custom',
        },
      ],
    },
  },
});

Changing it at runtime

logger.updateSanitizationConfig({ sensitiveFields: ['password', 'secret', 'token'] });
const current = logger.getSanitizationConfig();

Audit trail

With auditEnabled on, the SDK records each clean-up in memory: when it happened, sizes before and after, and which rules matched. It keeps the last 1,000 entries and never sends them anywhere. Read it while debugging your rules:

const entries = logger.getAuditTrail(); // [{ timestamp, operation, rulesApplied, ... }]
logger.clearAuditTrail();

Turning it off

import { Apperio } from 'apperio';

const logger = new Apperio({
  apiKey: 'your-api-key',
  projectId: 'your-project-id',
  sanitization: { enabled: false },
});