How to specify memory resources in lima/nerdctl

[doberkofler]

I'm trying to a run an Oracle Database in a Docker image in a lima environment on macOS and get a lot of errors related to the shm volume.

lima nerdctl run --detach --name="oracledb" --network="oraclenet" --memory="4g" --publish="1521:1521" --volume="/dev/shm" --tmpfs="/dev/shm:rw,exec,size=1g" qualiant/database

I did not find documentation that explains how memory resources are allocated in lima and wanted to ask a few specific questions:

1. Docker Desktop for macOS have an overall limit for memory consumption on the container. Where can I find this in lima?
2. nerdctl support the --memory option but how does this relate to lima? Is it guaranteed that the container gets 4g when using the --memory="4g" flag independently from lima?

Thank you!

[afbjorklund]

Docker Desktop for macOS have an overall limit for memory consumption on the container. Where can I find this in lima?

When you started the virtual machine, there was a YAML file to edit. It included fields like "cpus" and memory"

? Creating an instance "default"  [Use arrows to move, type to filter]
> Proceed with the default configuration
  Open an editor to override the configuration
  Exit

After it has been started, it is saved as ~/.lima/default/lima.yaml (or similar, for other instances than "default")

# CPUs: if you see performance issues, try limiting cpus to 1.
# Default: 4
cpus: 4

# Memory size
# Default: "4GiB"
memory: "4GiB"

# Disk size
# Default: "100GiB"
disk: "100GiB"

You need to restart it for changes to take effect. View changes with list.

Resizing the disk image is be a bit trickier, and requires manual commands.

[doberkofler]

Thank you for your feedback.
Could you please elaborate (or point me to the appropriate documentation) on how the memory option in the configuration file interacts with the container memory options when using nerdctl? What exactly does the memory configuration option of lima describe? Why do I not seem to get an error when starting a container with a memory command line option larger than the one in the lima configuration file?

[afbjorklund]

I think it is just a limit, you might run into hardware limitations (even virtual ones) before hitting such a software limit

$ lima nerdctl run --memory=32K busybox true
FATA[0000] failed to create shim: OCI runtime create failed: container_linux.go:380: starting container process caused: process_linux.go:545: container init caused: Running hook #0:: error running hook: exit status 1, stdout: , stderr: time="2021-12-04T13:20:44Z" level=fatal msg="stat /proc/2616/ns/net: no such file or directory"

$ lima nerdctl run --memory=32G busybox true
$

[afbjorklund]

What exactly does the memory configuration option of lima describe?

It is the total amount of memory available to the virtual machine created.

You can see how much is "left" after the kernel and other system processes:

$ lima free -h
               total        used        free      shared  buff/cache   available
Mem:           3.8Gi       208Mi       3.2Gi       1.0Mi       485Mi       3.4Gi
Swap:             0B          0B          0B

So we allocated 4.0 to the VM, where 3.8 was "total" and 3.4 is "available".

So if you want to start a process (container) with 4.0, memory needs to be 4.6+