https://jvns.ca/blog/2023/07/10/lima--a-nice-way-to-run-linux-vms-on-mac/

Julia Evans

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Lima: a nice way to run Linux VMs on Mac

* tools *

Hello! Here's a new entry in the "cool software julia likes" section.

A little while ago I started using a Mac, and one of my biggest
frustrations with it is that often I need to run Linux-specific
software. For example, the nginx playground I posted about the other
day only works on Linux because it uses Linux namespaces (via
bubblewrap) to sandbox nginx. And I'm working on another playground
right now that uses bubblewrap too.

This post is very short, it's just to say that Lima seems nice and
much simpler to get started with than Vagrant.

enter Lima!

I was complaining about this to a friend, and they mentioned Lima,
which stands for Linux on Mac. I'd heard of colima (another way to
run Linux containers on Mac), but I hadn't realized that Lima also
just lets you run VMs.

It was surprisingly simple to set up. I just had to:

 1. Install Lima (I did nix-env -iA nixpkgs.lima but you can also
    install it with brew install lima)
 2. Run limactl start default to start the VM
 3. Run lima to get a shell

That's it! By default it mounts your home directory as read-only
inside the VM

There's a config file in ~/.lima/default/lima.yaml, but I haven't
needed to change it yet.

some nice things about Lima

Some things I appreciate about Lima (as opposed to Vagrant which I've
used in the past and found kind of frustrating) are:

 1. it provides a default config
 2. it automatically downloads a Ubuntu 22.04 image to use in the VM
    (which is what I would have probably picked anyway)
 3. it mounts my entire home directory inside the VM, which I really
    like as a default choice (it feels very seamless)

I think the paradigm of "I have a single chaotic global Linux VM
which I use for all my projects" might work better for me than super
carefully configured per-project VMs. Though I'm sure that you can
have carefully configured per-project VMs with Lima too if you want,
I'm just only using the default VM.

problem: I don't know how to mount directories read-write

I wanted to have my entire home directory mounted read-only, but have
some subdirectories (like ~/work/nginx-playground) mounted
read-write. I did some research and here's what I found:

  * a comment on this github issue says that you can use mountType:
    "virtiofs" and vmType: "vz" to mount subdirectories of your home
    directory read-write
  * the Lima version packaged in nix 23.05 doesn't seem to support
    vmType: vz (though I could be wrong about this)

Maybe I'll figure out how to mount directories read-write later, I'm
not too bothered by working around it for now.

why not use containers?

I wanted a VM and not a Linux container because:

 1. the playground runs on a VM in production, not in a container,
    and generally it's easier to develop in a similar environment to
    production
 2. all of my playgrounds use Linux namespaces, and I don't know how
    to create a namespace inside a container. Probably you can but I
    don't feel like figuring it out and it seems like an unnecessary
    distraction.
 3. on Mac you need to run containers inside a Linux VM anyway, so
    I'd rather use a VM directly and not introduce another
    unnecessary layer

that's all!

Some other notes:

  * It looks like Lima works on Linux too
  * a bunch of people on Mastodon also said colima (built on top of
    Lima) is a nice Docker alternative on Mac for running Linux
    containers
  * there's also an new alternative Linux container runtime for Mac
    called Orb Stack, which I know nothing about

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Open sourcing the nginx playground

Archives (c) Julia Evans. If you like this, you may like Ulia Ea or,
more seriously, this list of blogs I love or some books I've read.

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