BarelyQuestions
Questions about Barely
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Before you try it
What is Barely?
Barely is a memory friendly container manager for Docker on Apple Silicon Macs. It puts idle containers to sleep and wakes them in milliseconds. RAM and other resources return to macOS while not in use.
Which Macs does it run on?
Apple Silicon Macs with macOS 14 or later. On an Intel Mac, Barely doesn't run.
Does it work with docker compose?
Yes. Inside the VM is the standard Docker engine, so docker compose works as it is. A docker compose stack sleeps and wakes whole, never in part.
Do my compose files or docker commands change?
No. Inside the VM is the standard Docker engine. Your compose files, docker commands and scripts run as they are, and published ports are on localhost.
Can I run it alongside Docker Desktop?
Yes. You can keep Docker Desktop installed and run both. They don't share anything: each has its own images, containers and volumes. In the app, Settings › Doctor shows which one docker is using, and Settings › Docker switches it back to Barely. See Alongside Docker Desktop.
What does setup change on my Mac?
It registers a docker context called barely and asks whether to make it the current one, points /var/run/docker.sock at Barely, and can set DOCKER_HOST in your shell profile. Setup asks before each change it makes.
Can I run amd64 images?
No. arm64 images only, no Rosetta. An image built only for Intel and AMD (amd64) won't run.
Do file watchers and hot reload work in containers?
Yes. Saving a file on your Mac fires the watcher in the container. Only a touch that changes nothing but the timestamp goes unseen.
Sleep and hibernate
When does a container go to sleep?
When nothing has used it for a while: no network traffic in or out, nothing written to its logs, no file changed in its bind mounts, little CPU, and no cron daemon or timer in it. Barely then pauses it and gives its RAM back to macOS.
What wakes a sleeping container?
A new connection to it, such as a request to a published port; a docker command that acts on it, such as exec, attach, stop or restart; and a file changed in its bind mounts.
How fast does it wake?
On a MacBook Air with 16 GB of RAM, a request to a sleeping container's port was answered in 10 to 60 milliseconds, waking the container on the way, and a docker exec into a sleeping container took under a tenth of a second. From a hibernated VM, the next docker command was answered in about a quarter of a second.
Do docker ps or docker logs wake it?
No. Commands that only read, such as docker ps, docker logs, docker inspect and docker stats, don't wake it. A request to its port, a docker command that acts on it, such as exec or restart, or a file saved in its bind mounts does.
What happens to open connections while it sleeps?
They stay open, and the next bytes sent on one wake the container. When every container is asleep and the VM hibernates, streams like docker logs -f end and need starting again.
What about a container that runs cron jobs?
Containers with scheduled work, like cron or a systemd timer, stay awake. A schedule inside an app's own process, such as node-cron, isn't seen as use: switch on Keep awake for that container.
How do I keep a container awake?
Switch on Keep awake for it in the app, for one container or a whole docker compose stack. In a compose file, the label barely.sleep: "false" does the same; with docker run, --label barely.sleep=false.
What happens when every container is asleep?
The VM saves its memory to disk and exits. Barely scales all the way to zero: no VM, no RAM, no CPU. The next docker command, or a request to a published port, brings it back in about a quarter of a second, with containers where they were.
How much disk does a hibernated VM take?
About as much as the RAM it was using. With nothing up, the VM shuts down instead and saves nothing.
Memory and disk
Does the RAM a build uses come back to my Mac?
Yes. The VM grows while a build runs and shrinks when it finishes. On a 16 GB Mac, a build took the VM to 7.0 GB. Within 30 seconds of the build ending, the VM was back to 2.4 GB, what the running stack needed.
How do I get disk space back from Docker?
On Barely, delete what you don't need, in the app or with docker. Deleting an image, container or volume frees its space on your Mac, and so does clearing the build cache.
Can I change how much RAM or disk Barely can use?
Yes, in the app under Settings › Resources. The memory limit is half your Mac's RAM by default, and the disk limit is 100 GB. The disk limit can be raised later, not lowered.
The app
What does the app show?
Barely is a Mac app. It shows every container and process, what each one is using, and which containers are asleep, with logs, shells, files, images and builds. See the app.
Does the app keep the VM awake?
No. With the app open, containers still go to sleep and the VM still hibernates when idle. The app doesn't start a stopped VM unless you press Start.
Is there a command line?
Yes. Barely comes with its own command, barely, which shows the same as the app in the terminal, such as barely status and barely top. barely help lists every command.
Price and licence
Is it a subscription?
No subscription. You pay $99 once.
Is there a free trial?
Yes, the 30-day trial. It is all of Barely, and the trial needs no account, email or credit card. Install it with brew install barelyvm/tap/barely, and barely setup starts the trial.
What happens when the trial ends?
When the trial ends, Barely won't start until you buy a licence. Your images, containers and volumes stay where they are, and barely uninstall puts docker back the way it was.
Can I use it on more than one Mac?
Yes. A licence is for one user, on each of your Macs.
Who takes the payment?
Polar.sh, the merchant of record. Polar.sh handles sales tax and VAT, and sends your receipt.
Can I get a refund?
Yes. Ask within 30 days of buying, and you don't need to give a reason. See the refund policy.
Is it open source?
No. Barely is closed source software. The open source parts it bundles keep their own licences, and each release publishes the source of the guest's GPL-licensed parts. See licences.
Leaving
How do I go back to what I used before?
barely uninstall removes Barely and puts docker back the way it was before setup.
Do I lose my images if I uninstall?
Not unless you say so. barely uninstall asks whether to delete your images, containers, volumes, licence, logs and settings too, and the answer is no unless you say yes.
Try it on your own containers
The trial is 30 days and needs no account, email or credit card. Purchase at any time, $99 once.