reqlog

Search and trace requests across microservices, files, and Docker logs — fast.
Debug distributed systems using simple key/value search (e.g. request_id, trace_id) without relying on centralized tracing.

Why reqlog?

Debugging logs in microservices usually means:

• jumping between multiple files
• dealing with inconsistent formats
• writing fragile grep | awk | sort pipelines

reqlog fixes this in one command.

• Search logs across multiple services
• Match structured fields like request_id, trace_id
• Get a chronological flow of a request
• Visually scan logs with service-based colors

Companion web UI for reqlog: https://github.com/sagarmaheshwary/reqlog-ui

Quick Start

reqlog --dir ./logs --key request_id abc123

Example output:

2026-03-20T14:10:00.000Z [api-gateway]    | start request
2026-03-20T14:10:01.000Z [order-service]  | fetching order
2026-03-20T14:10:02.000Z [inventory]      | checking stock

Follow a request across services in seconds.

Features

• Key-based search (--key request_id)
• Fast scanning (millions of lines)
• Supports plain text + JSON logs
• Docker logs support
• Filter by service (--service, supports wildcards)
• Time filtering (--since)
• Colored output by service
• Live tailing (--follow)
• Case-insensitive search
• Works across multiple files & directories

Installation

Go Install

go install github.com/sagarmaheshwary/reqlog/cmd/reqlog@latest

macOS / Linux

curl -sSL https://raw.githubusercontent.com/sagarmaheshwary/reqlog/master/install.sh | bash

• Auto-detects OS/arch
• Installs latest version
• Installs to /usr/local/bin

Verify:

reqlog --version

Windows

Download from:

https://github.com/sagarmaheshwary/reqlog/releases

Then:

• unzip
• add to PATH

Verify:

reqlog --version

Usage

reqlog [flags] <search_value>

Basic Search

reqlog --dir ./logs abc123

Key-Based Search (Recommended)

reqlog --key request_id abc123
reqlog --key event_key order.created

JSON Logs

reqlog --dir ./logs --json --key trace_id trace-123

Docker Logs

reqlog --source docker --service api-gateway abc123

Wildcard support:

reqlog --service order-service* abc123

--service filters container names when using --source docker; otherwise, it filters log file names.

Time Filtering

reqlog --since 10m --key request_id abc123
reqlog --since 2026-04-29 --key request_id abc123
reqlog --since 2026-04-29T14:00:00Z --key request_id abc123
reqlog --since 2026-04-29T14:00:00.123Z --key request_id abc123
reqlog --since 1710943200 --key request_id abc123

Follow Logs (Live)

reqlog --follow --key request_id abc123

Full usage guide: docs/usage.md

Why not just use grep?

Problem	grep	reqlog
Multi-file search	⚠️ manual	✅ built-in
Request tracing	❌	✅
JSON logs	❌	✅
Chronological flow	❌	✅
Service context	❌	✅

reqlog = grep for distributed systems

Performance

• ~9.6M lines scanned in ~2 seconds
• ~9 MB memory usage
• Works efficiently on real-world datasets

Optimized for sequential reads + minimal memory usage

Supported Log Formats

Supported Timestamp Formats

• RFC3339 / ISO-8601
  • with or without fractional seconds
• Unix timestamps
  • seconds (10 digits)
  • milliseconds (13 digits)
  • microseconds (16 digits)
  • nanoseconds (19 digits)

Timestamps are normalized to millisecond precision in output (fixed 3 digits).

Text Logs

• Timestamp must appear as the first field
• Supports key=value fields

2026-03-20T14:00:00Z request_id=abc123 start request
2026-03-20T14:00:00.123Z request_id=abc123 processing
1710943200 request_id=abc123 unix seconds
1710943200123 request_id=abc123 unix milliseconds

JSON Logs

• One JSON object per line
• Supported timestamp fields: time, timestamp, ts

{ "time": "2026-03-20T14:10:00Z", "request_id": "abc", "message": "start" }
{ "time": "2026-03-20T14:10:00.456Z", "request_id": "abc", "message": "processing" }
{ "ts": 1710943200, "request_id": "abc", "message": "unix seconds" }
{ "ts": 1710943200123, "request_id": "abc", "message": "unix milliseconds" }

Roadmap

Core Features

• Flexible timestamp parsing (RFC3339 / RFC3339Nano)
• Text log parsing (key=value)
• JSON log parsing
• Wildcard support in --service (e.g. order-service*)
• Unix timestamp support (logs + --since)
• Optimize --limit (early exit / streaming)
• --context flag (show surrounding lines)
• --fields flag for JSON logs
• --output=json for piping and integrations

Performance & Scalability

• Parallel scanning
• General performance improvements

Integrations

• File logs
• Docker logs
• Kubernetes logs

Contributing

Contributions and feedback are welcome!

License

MIT