zrepl status subcommand

[zrepl]

zrepl status subcommand

[problame]

Use Cases

Interactive System Administration & Debugging

• Show snapshots and bookmarks created by a job, sorted by createtxg, with creation date and scheduled pruning date (not possible with grid policy)
• Learn about the state of a job
  • what tasks are sleeping, what tasks are doing somehting? (! multiple concurrent tasks !)
  • For how long is a sleeping task going to sleep? Since when does it sleep? (UTC for log!)
  • replication tasks
    • what filesystem is it replicating, at what speed / number of bytes txed?
    • diff error visualization
      • pretty-print a diff
      • ad-hoc compute a new diff
  • Attach to the log of a single job at a user-specified level (Crazy?)
    • Or: Show the last N bytes of warn log with timestamp?
    • Or: Show warn log since last run of task

Monitoring

• Simple binary check via exit status: green or anything red
• Detailed errors are can be found through log monitoring warn log
• Monitoring should not rely on zrepl output to check if replication actually worked
  • short script a la zfs list -o creation -t snapshot -s creation -r -d 1 filesystem/to/check | tail -n 1 | ... sufficient, should already exist in your org

Implementation Concerns

• control socket is currently only accessible to zrepl user due to lack of authentication / authorization mechanisms.
• monitoring tools would likely use an HTTP API
• the same API should be consumed by the CLI frontend
• consider possibility of web-based zrepl status one day -> streaming interface?
• requires refactoring of existing control socket api

[problame]

@woodsb02 It's still a bit early, but you can test the status functionality by building this branch status_command.
Status can be displayed using zrepl control status, the raw JSON exposed by zrepl daemon can be displayed using the --format json argument.

What do you think?

[problame]

• Task API
• Cleanup adoption throughout zrepl
• Use show lastChanged in zrepl control status

[problame]

merged.

list command is tracked in #49