sapphiccode/balloond

An automatic libvirt memory balloon daemon

Hi, I'm Cassandra. I've made the occasional name for myself.

I primarily work with

• Python
• Golang
• Infrastructure automation tooling (Terraform, Ansible, etc)
• CI/CD tooling
  • shell scripting
  • 🗑️ GitHub Actions
  • 🥉 Bitbucket Pipelines
  • 🥈 GitLab CI
  • 🥇 Concourse CI

I am interested in

• Rust
• Julia

I will never touch

• C
• C++
• Assembly

You may know me from

• The Discord API / bot scene, 2016-2018
• way too many sideprojects I've put my name on
• "That girl who does way too much shit with Hashicorp Vault."

balloond's Issues

Allow for faster reaction times using an agent inside the VM

Making an agent inside the VM the source of truth for memory statistics would reduce reliance on (seemingly often inaccurate) libvirt-provided memory statistics, and make the entire system more responsive.

Theoretically, this should not be a DoS risk, unless an attacker gains access to multiple VMs which are already competing for memory, since every VM still has its maximum memory bottleneck.

Ultimately, this would also allow us to drop our headroom size down a lot, since every VM would be reporting in every second (or faster!), which in turn would allow us to react faster to changes thus necessitating less buffer room.

Issue on Libvirt 6.5.0

Hi, i'm trying it on a Unraid server 6.9.2, with Libvirt 6.5.0
On my first try, I got the message "Libvirt is returning garbage statistics. Protecting ourselves."
Checking the code I found in domain.go, that you check this: "if current < available "
Using "virsh dommemstat" I've checked that the available value it will be always greater than current value (actual on my virsh).
So I change the comparison sign and it start working.
Idk if something change in the past 2 years, this is the output of the virsh command of a 8Gb VM, allocating only half the memory.

actual 4194304
swap_in 0
swap_out 0
major_fault 61
minor_fault 87934
unused 8040536
available 8145192
usable 7921156
last_update 1628808819
disk_caches 28468
hugetlb_pgalloc 0
hugetlb_pgfail 0
rss 4274492

Allow for configuration overrides in VM config using metadata

This is good if, for instance, you want a build host or a game server (which allocate memory quite fast) to have enough headroom to allocate memory.

We should be able to store these config overrides in the domain metadata and cache them into balloond when it's making use of them.

Another useful addition would be the ability to manually disable management of a VM's balloon driver without removing the balloon driver itself from the VM.