log-file-rotation

Log file rotation

Write a service's output to a file and rotate it by size, keeping a bounded number of compressed history files.

Config

# File log target with size-based rotation and retention.
processes:
  - name: app
    command: /usr/local/bin/app
    args: ["300"]
    on-failure: shutdown
log-targets:
  app-file:
    type: file
    location: /var/log/app.log
    services: [app]
    max-size: 10MiB
    max-files: 5
    compress: true

• type: file — write to a file rather than syslog.
• location — the active log file path.
• services — only forward output from these services (omit for all).
• max-size — rotate when the file would exceed this size (e.g. 10MiB).
• max-files — retain this many rotated files (app.log.1 ... app.log.5).
• compress — gzip rotated files (app.log.1.gz, app.log.2.gz, ...).

Expected behavior

• app output is written to /var/log/app.log.
• When the file would exceed 10 MiB, it rotates: existing files shift up by one and a fresh app.log is opened.
• At most 5 rotated files are kept; older ones are deleted.
• Rotated files are gzip-compressed.

Test

ValidateParse level — behavior is environment-dependent (cgroup limits / remote syslog / file rotation thresholds), so the test asserts the config loads and validates.

go test ./documentation/log-file-rotation/ -v