Introducing Virtainer Free 1.1

Today we are releasing Virtainer Free 1.1, the first major update since Virtainer went public in June. It is still free, and it is available now on the stable channel.

1.0 was about getting a host up and running your workloads. 1.1 is about the machines themselves. A classic VM on Virtainer is now provisioned, reached, snapshotted and rolled back by software we wrote, test and ship ourselves, rather than by whatever each Linux distribution happens to install.

Built by us, down to the guest

Many virtualization platforms stop at the edge of the VM. Inside it they rely on whichever agent the distribution’s packages provide, installed from the network at first boot, and each distribution behaves a little differently. With 1.1 that edge is ours too.

Our own guest agent. Every classic VM gets the Virtainer guest agent, a single 1 MB binary that ships inside Virtainer itself. Nothing is downloaded, nothing differs by distribution, and a VM with no network access still has an agent. When we fix something, every VM gets the fix, and the console shows you which machines still need it, with one click to update them.
Images understood before they boot. Every image you add is read by cloud-image-inspector, which looks inside a cloud image without booting or mounting it. First-boot setup is then written for what is actually in that image, not for what its name suggests. Alpine works out of the box, users get a login shell the image really has, and an image that can only boot through BIOS is turned away when you add it, not after you have waited for a black screen.

We have open-sourced both under Apache-2.0. Everything Virtainer puts inside your VMs is code you, and your security team, can read.

What it means for the machines you run

A shell that is always there. The Shell tab opens a terminal in the VM through Virtainer itself. It works without a network inside the VM and without SSH, with several sessions at once, and every session is recorded in the audit log. When a machine is not healthy, the console offers the Rescue console, which shows the machine from the first moment of boot.

Snapshots in seconds, rollback of the whole machine. Taking a snapshot no longer copies the disk, whether the VM is running or not. Rolling back restores the machine as it was, including its disks and network interfaces. Every snapshot states honestly how consistent it is, and snapshots travel with a VM when you export it.

Network interfaces that come and go. An interface is now a resource of its own: add it to a running VM, remove it, move it to another machine.

Hot-added CPU and memory that actually come online, on every distribution we support, including the ones whose images leave them offline by default.

Stable by design, and by process

Virtainer Free runs on a host that cannot be half-updated. The whole system is one image: an update switches to the new image in one step, and if anything is wrong, you roll back with one reboot. Your configuration and your VMs stay where they are.

1.1 went through forty release candidates before it reached the stable channel. Each one was installed on real hardware the same way you will install it, as an image update, and checked there before the next one was cut. Nothing reaches stable on the strength of tests alone.

Smaller things in this release follow the same line. A laptop host no longer suspends when its lid closes. New hosts refuse root login over SSH. A host network change that has not been confirmed is rolled back rather than left half-applied. And a VM that simply has not reported in yet is shown as No boot signal, not as failed.

Get it

Existing hosts update from OS Updates in the console. If a host is still on 1.0.0, run systemctl mask boot.automount at its console before updating; this is needed only once, and the update guide explains why.

New to Virtainer? Free is free, with no per-core licensing and no time limit. The install guide sets up a host, and the user guide covers everything in this release in detail, from the guest agent to snapshots.