What you need
- Multimeter for macOS 13 or later, $19.99 once.
- The direct download version of Multimeter from this site (the Script source isn’t in the Mac App Store version).
- Docker Desktop, OrbStack or Colima running (anything that provides the
dockercommand).
Set it up
- Check the count in Terminal:Command
docker ps -q | wc -l - Add a Script meter with it, refreshing every 30 seconds.
- Set the range to 0 to how many containers you expect, with alerts on Low values one under that.
Multimeter settings
In Customize This Meter… (from the meter’s menu):
| Setting | Value |
|---|---|
| Source | Script |
| Command | docker ps -q | wc -l |
| Refresh every | 30 seconds |
| Range | 0 to your usual count, like 8 |
| Alerts | Low values: warning 7, critical 5 |
| Label | DOCK |
| Face | Book Power, Hearts or Columns |
Tested: Run on October 29, 2026 with Docker Desktop 28 and six containers: printed 6 in 0.3 seconds; the unhealthy filter printed 0.
Script meters need the direct download version of Multimeter from this site, which is the one on sale now. How commands run, the PATH they see and the 10 second limit are in the Script meters guide.
Variations
Unhealthy containers
Alerts on High values with critical at 1.
Command
docker ps --filter health=unhealthy -q | wc -lStopped containers
Command
docker ps -a --filter status=exited -q | wc -lOn a server over SSH
Needs key-based SSH login with no prompts.
Command
ssh -o BatchMode=yes -o ConnectTimeout=5 user@server 'docker ps -q | wc -l'Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| The script didn’t print a number | The command failed or printed an error message instead. | Run the exact command in Terminal. If it works there, check for tools that live outside the meter’s PATH and use their full path (which tool). |
| The script took longer than 10 seconds | A slow network call. Multimeter stops scripts after 10 seconds. | Keep the -m timeout on curl, and refresh less often. |
| Scripts need the version from multimeterapp.com | This copy of Multimeter came from the Mac App Store, which can’t run scripts. | Use the direct download version, or run the command from cron or launchd and point a File meter at its output. |
| Shows 0 even though containers run | The Docker engine isn’t running, so docker ps failed and printed nothing to count. | Start Docker Desktop (or OrbStack, Colima) and refresh. |
Questions
Does this work in the Mac App Store version?
Script meters need the direct download version from multimeterapp.com, because the App Store sandbox doesn’t let apps run your commands. Web Address, File and Sent Value meters work in every version.
Does it slow Docker down?
No. docker ps is a quick read of the engine’s state.