Show a barca server's run queue, or pause or resume it (experimental)

The queue holds the runs a server accepted and has not finished, in order. It lives on the server: the command needs one (--server URL, BARCA_SERVER or [server] url).

Usage: barca queue [OPTIONS] [ACTION]

Arguments:
  [ACTION]
          pause: queued runs wait until resumed (runs in flight go on); resume: they start again. Omit to show the queue

          Possible values:
          - pause:  Hold every queued run back until resumed
          - resume: Let queued runs start again, in order

Options:
      --json
          Emit JSON on stdout (the default when stdout is not a terminal)

      --pretty
          Emit human-readable output (the default when stdout is a terminal)

      --env <ENV>
          The server's environment, checked against it (as for the other --server commands)

      --server [<URL>]
          Run this command on a barca server (`barca serve`) and print its result here: the URL given, or with no URL the configured one (BARCA_SERVER, else [server] url in barca.toml). Without it, get and run run on this machine (against a configured server's ledger), status, history, stats and logs are answered by a configured server, and sql resolves its views from it (the query always runs here)

      --local
          Ignore any configured server for this command: run against this machine's own ledger and records; nothing is read from or sent to the server

  -h, --help
          Print help (see a summary with '-h')

Examples:
  barca queue --server                 # the configured server's run queue: running and queued runs
  barca queue --server http://barca.internal:8274 --json  # {paused, paused_at, draining, max_runs, running, queued}
  barca queue pause --server           # queued runs wait (runs in flight go on); kept across restarts
  barca queue resume --server          # queued runs start again, in order
  barca queue                          # the server in BARCA_SERVER or [server] url

Every run a server accepts (POST /runs, --server, the UI, a scheduled tick) joins its run queue,
recorded in the metadata DB, and starts in order when fewer than --max-runs run. While paused,
new runs and ticks still join the queue; nothing new starts. A restart keeps the queue and the
pause: queued runs resume under their run ids. Exit 2 with no server configured or on a
--read-only server (pause and resume), 3 when the server cannot be reached. Experimental.
More: barca docs scheduling
