Docker logging drivers and centralized log management

Where Container Logs Go and How to Control Them

Docker captures everything written to stdout and stderr from a container. The logging driver controls where that output goes. The default driver, json-file, writes to a file on the host — which can grow unbounded and fill your disk.

Log Rotation with json-file

docker run -d \
  --log-driver json-file \
  --log-opt max-size=10m \
  --log-opt max-file=3 \
  my-app

This keeps at most 3 files of 10MB each — 30MB maximum. Always set these options in production.

Shipping Logs to a Central System

# Send logs to AWS CloudWatch
docker run -d \
  --log-driver awslogs \
  --log-opt awslogs-region=us-east-1 \
  --log-opt awslogs-group=/my-app/prod \
  my-app

For Compose, set logging per service:

services:
  api:
    logging:
      driver: json-file
      options:
        max-size: "10m"
        max-file: "3"

Write only to stdout/stderr in your app — never write to files inside the container. Docker cannot capture file-based logs, and files are lost when the container is removed.