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Docker Container Log — json-file driver (log)

A Docker json-file container log — one JSON object per line with the log text, stream (stdout/stderr), and an RFC 3339 timestamp, exactly as Docker's default logging driver writes it. A fixture for container-log shippers and parsers.

Log parsingObservabilityJSON parsing
Preview — first 27 lineslog
{"log": "Listening on :8080\n", "stream": "stdout", "time": "2026-01-15T12:00:03.533Z"}
{"log": "Listening on :8080\n", "stream": "stdout", "time": "2026-01-15T12:00:03.770Z"}
{"log": "cache hit key=session:abc\n", "stream": "stdout", "time": "2026-01-15T12:00:05.742Z"}
{"log": "WARN slow query 812ms\n", "stream": "stderr", "time": "2026-01-15T12:00:06.645Z"}
{"log": "connection pool size=10 in-use=3\n", "stream": "stdout", "time": "2026-01-15T12:00:09.663Z"}
{"log": "connection pool size=10 in-use=3\n", "stream": "stdout", "time": "2026-01-15T12:00:11.729Z"}
{"log": "ERROR upstream timeout\n", "stream": "stderr", "time": "2026-01-15T12:00:15.556Z"}
{"log": "connection pool size=10 in-use=3\n", "stream": "stdout", "time": "2026-01-15T12:00:17.112Z"}
{"log": "WARN slow query 812ms\n", "stream": "stderr", "time": "2026-01-15T12:00:19.877Z"}
{"log": "ERROR upstream timeout\n", "stream": "stderr", "time": "2026-01-15T12:00:21.671Z"}
{"log": "WARN slow query 812ms\n", "stream": "stderr", "time": "2026-01-15T12:00:24.600Z"}
{"log": "GET /api/products/999 404 5ms\n", "stream": "stdout", "time": "2026-01-15T12:00:25.309Z"}
{"log": "cache hit key=session:abc\n", "stream": "stdout", "time": "2026-01-15T12:00:28.741Z"}
{"log": "GET /api/products/999 404 5ms\n", "stream": "stdout", "time": "2026-01-15T12:00:31.548Z"}
{"log": "GET /health 200 3ms\n", "stream": "stdout", "time": "2026-01-15T12:00:31.762Z"}
{"log": "ERROR upstream timeout\n", "stream": "stderr", "time": "2026-01-15T12:00:34.445Z"}
{"log": "cache hit key=session:abc\n", "stream": "stdout", "time": "2026-01-15T12:00:37.395Z"}
{"log": "cache hit key=session:abc\n", "stream": "stdout", "time": "2026-01-15T12:00:40.383Z"}
{"log": "connection pool size=10 in-use=3\n", "stream": "stdout", "time": "2026-01-15T12:00:41.540Z"}
{"log": "cache miss key=products:42\n", "stream": "stdout", "time": "2026-01-15T12:00:41.850Z"}
{"log": "POST /api/orders 201 44ms\n", "stream": "stdout", "time": "2026-01-15T12:00:44.273Z"}
{"log": "cache miss key=products:42\n", "stream": "stdout", "time": "2026-01-15T12:00:45.088Z"}
{"log": "GET /api/products/999 404 5ms\n", "stream": "stdout", "time": "2026-01-15T12:00:45.456Z"}
{"log": "WARN slow query 812ms\n", "stream": "stderr", "time": "2026-01-15T12:00:47.829Z"}
{"log": "GET /api/products/999 404 5ms\n", "stream": "stdout", "time": "2026-01-15T12:00:50.575Z"}
{"log": "GET /health 200 3ms\n", "stream": "stdout", "time": "2026-01-15T12:00:53.734Z"}

Specifications

Lines
26
Driver
json-file
Schema
log, stream, time
Seed
504

What is a .log file?

LOG files are plain-text records of events emitted by software, typically one entry per line with a timestamp, severity, and message. There is no single standard, so formats range from unstructured text to structured JSON lines. They are central to debugging, monitoring, and auditing.

How to use this file

Use an example LOG file to test log parsers, timestamp and severity extraction, line-oriented streaming, and ingestion into monitoring or analysis pipelines.

Related files

Generated by generation/data_logs.py. Free for any use, no attribution required — license.