logpare

Types Reference

Complete TypeScript type definitions for logpare

Complete TypeScript type definitions for logpare.

Core Types

CompressionResult

Result object returned by compress() and compressText().

interface CompressionResult {
  templates: Template[];
  stats: CompressionStats;
  formatted: string;
}

Fields:

  • templates - Array of discovered templates, sorted by occurrence count (descending)
  • stats - Compression statistics
  • formatted - String representation in the requested format

Template

Represents a discovered log template with metadata.

interface Template {
  id: string;
  pattern: string;
  occurrences: number;
  sampleVariables: string[][];
  firstSeen: number;
  lastSeen: number;
  severity: Severity;
  urlSamples: string[];
  fullUrlSamples: string[];
  statusCodeSamples: number[];
  correlationIdSamples: string[];
  durationSamples: string[];
  isStackFrame: boolean;
}

Fields:

  • id - Unique template identifier
  • pattern - Template pattern with <*> wildcards for variables
  • occurrences - Number of log lines matching this template
  • sampleVariables - Sample values captured from variables (limited by maxSamples)
  • firstSeen - Line number where template was first seen
  • lastSeen - Line number where template was last seen
  • severity - Severity level: 'error', 'warning', or 'info'
  • urlSamples - Extracted hostnames from URLs
  • fullUrlSamples - Complete URLs found in matching logs
  • statusCodeSamples - HTTP status codes (e.g., [200, 404, 500])
  • correlationIdSamples - Trace/request IDs for distributed tracing
  • durationSamples - Timing values (e.g., ["45ms", "1.5s"])
  • isStackFrame - Whether this template represents a stack frame

CompressionStats

Statistics about the compression operation.

interface CompressionStats {
  inputLines: number;
  uniqueTemplates: number;
  compressionRatio: number;
  estimatedTokenReduction: number;
  processingTimeMs?: number;
}

Fields:

  • inputLines - Number of input log lines processed
  • uniqueTemplates - Number of unique templates discovered
  • compressionRatio - Ratio of templates to input lines (0.0 to 1.0)
  • estimatedTokenReduction - Estimated token savings as percentage (0-100)
  • processingTimeMs - Time taken to process (milliseconds)

Options Types

CompressOptions

Options for compress() and compressText().

interface CompressOptions extends DrainOptions {
  format?: OutputFormat;
  maxTemplates?: number;
}

Fields:

  • format - Output format: 'summary', 'detailed', or 'json' (default: 'summary')
  • maxTemplates - Maximum templates in formatted output (default: 50)
  • Plus all fields from DrainOptions

DrainOptions

Configuration for the Drain algorithm.

interface DrainOptions {
  depth?: number;
  simThreshold?: number;
  maxChildren?: number;
  maxClusters?: number;
  maxSamples?: number;
  preprocessing?: ParsingStrategy;
  onProgress?: ProgressCallback;
}

Fields:

  • depth - Parse tree depth (default: 4)
  • simThreshold - Similarity threshold 0-1 (default: 0.4)
  • maxChildren - Max children per tree node (default: 100)
  • maxClusters - Max total templates (default: 1000)
  • maxSamples - Sample variables per template (default: 3)
  • preprocessing - Custom preprocessing strategy
  • onProgress - Progress reporting callback

Preprocessing Types

ParsingStrategy

Strategy for preprocessing and tokenizing log lines.

interface ParsingStrategy {
  preprocess(line: string): string;
  tokenize(line: string): string[];
  getSimThreshold(depth: number): number;
}

Methods:

  • preprocess(line) - Preprocess a log line (mask variables, normalize, etc.)
  • tokenize(line) - Split preprocessed line into tokens
  • getSimThreshold(depth) - Get similarity threshold for a given tree depth

Example:

import { defineStrategy, DEFAULT_PATTERNS, WILDCARD } from 'logpare';

const customStrategy: ParsingStrategy = defineStrategy({
  preprocess(line: string): string {
    let result = line;
    for (const [, pattern] of Object.entries(DEFAULT_PATTERNS)) {
      result = result.replace(pattern, WILDCARD);
    }
    return result;
  },

  tokenize(line: string): string[] {
    return line.split(/\s+/).filter(Boolean);
  },

  getSimThreshold(depth: number): number {
    return depth <= 2 ? 0.3 : 0.4;
  }
});

Progress Types

ProgressCallback

Callback function for progress updates.

type ProgressCallback = (event: ProgressEvent) => void;

ProgressEvent

Progress event data.

interface ProgressEvent {
  processedLines: number;
  totalLines?: number;
  currentPhase: ProcessingPhase;
  percentComplete?: number;
}

Fields:

  • processedLines - Number of lines processed so far
  • totalLines - Total lines to process (if known)
  • currentPhase - Current processing phase
  • percentComplete - Completion percentage 0-100 (only if totalLines known)

ProcessingPhase

Current phase of the compression operation.

type ProcessingPhase = 'parsing' | 'clustering' | 'finalizing';

Enum Types

Severity

Log severity level.

type Severity = 'error' | 'warning' | 'info';

Automatically detected from log content:

  • 'error' - ERROR, FATAL, Exception, Failed, TypeError, etc.
  • 'warning' - WARN, Warning, Deprecated, [Violation]
  • 'info' - Default for other logs

OutputFormat

Output format for compression results.

type OutputFormat = 'summary' | 'detailed' | 'json';
  • 'summary' - Compact template list with frequencies
  • 'detailed' - Full templates with all metadata
  • 'json' - Machine-readable JSON

Constants

WILDCARD

The wildcard placeholder used in templates.

const WILDCARD: '<*>';

Example:

import { WILDCARD } from 'logpare';

const pattern = `ERROR Connection to ${WILDCARD} failed`;

DEFAULT_PATTERNS

Built-in regex patterns for common log variables.

const DEFAULT_PATTERNS: {
  ipv4: RegExp;
  ipv6: RegExp;
  uuid: RegExp;
  timestamp: RegExp;
  hexId: RegExp;
  filepath: RegExp;
  url: RegExp;
  number: RegExp;
  // ... more patterns
};

Example:

import { DEFAULT_PATTERNS } from 'logpare';

// Use in custom preprocessing
const masked = line.replace(DEFAULT_PATTERNS.ipv4, '<*>');

SEVERITY_PATTERNS

Regex patterns for severity detection.

const SEVERITY_PATTERNS: {
  error: RegExp;
  warning: RegExp;
};

STACK_FRAME_PATTERNS

Regex patterns for stack frame detection.

const STACK_FRAME_PATTERNS: {
  v8: RegExp;
  firefox: RegExp;
  chrome: RegExp;
};

Utility Functions

detectSeverity()

Detect severity level from a log line.

function detectSeverity(line: string): Severity;

Example:

import { detectSeverity } from 'logpare';

detectSeverity('ERROR Connection failed');  // 'error'
detectSeverity('WARN Deprecated API');      // 'warning'
detectSeverity('INFO Request completed');   // 'info'

isStackFrame()

Check if a line is a stack frame.

function isStackFrame(line: string): boolean;

Example:

import { isStackFrame } from 'logpare';

isStackFrame('    at Function.name (file.js:123:45)');  // true
isStackFrame('ERROR Connection failed');                 // false

extractUrls()

Extract URLs/hostnames from a log line.

function extractUrls(line: string): string[];

Example:

import { extractUrls } from 'logpare';

extractUrls('GET https://api.example.com/users');
// ['api.example.com']

extractUrls('Fetched http://cdn.example.com/image.png');
// ['cdn.example.com']

defineStrategy()

Create a custom preprocessing strategy.

function defineStrategy(
  overrides: Partial<ParsingStrategy>
): ParsingStrategy;

Example:

import { defineStrategy } from 'logpare';

const strategy = defineStrategy({
  tokenize: (line) => line.split(','),
  getSimThreshold: (depth) => 0.5,
});

See Also

createDrain()

Create a Drain instance for incremental or streaming log processing

Parameter Tuning Guide

Learn how to optimize logpare's parameters for different log types

On this page

Core TypesCompressionResultTemplateCompressionStatsOptions TypesCompressOptionsDrainOptionsPreprocessing TypesParsingStrategyProgress TypesProgressCallbackProgressEventProcessingPhaseEnum TypesSeverityOutputFormatConstantsWILDCARDDEFAULT_PATTERNSSEVERITY_PATTERNSSTACK_FRAME_PATTERNSUtility FunctionsdetectSeverity()isStackFrame()extractUrls()defineStrategy()See Also