I've been using unikraft (https://unikraft.org/) unikernels for a while and the startup times are quite impressive (easily sub-second for our Rust application).

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ahepp 16 hours ago | parent | next [-]

What drove you to choose that over something like containers?

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droelf 14 hours ago | parent | next [-]

Yeah, boot time, isolation (proper VM vs containers), and ease of use on a larger Hetzner box.

	▲	ahepp 13 hours ago \| parent [-]
		Did you notice a substantial difference in those factors between more traditional micro VMs that use OCI images (like Firecracker) and unikernels?

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m00dy 16 hours ago | parent | prev [-]

shorter cold-boot times.

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ahepp 14 hours ago | parent | next [-]

If we’re talking about cold boot times, wouldn’t the relevant metric for unikernels be the hypervisor’s boot time?

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zozbot234 13 hours ago | parent | prev [-]

How would that compare with containers running on Firecracker or other virtio-based μVM's?

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wmf 13 hours ago | parent [-]

A unikernel on Firecracker is probably going to start faster than a container on Linux on Firecracker.

	▲	ahepp 13 hours ago \| parent [-]
		I assume they meant using an OCI image for the rootfs of a firecracker VM, not running a container inside a firecracker VM. Still difficult to see how the unikernel could be slower, but I doubt the difference would be huge? Don't have anything to back that up though.

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ATechGuy 14 hours ago | parent | prev [-]

Fast boot up means nothing if your agent/app is slow at runtime (due to virtualization tax or QEMU emulation). Fast boot up is a PR term, which can easily be optimized for compared to designed a better virtualization layer that performs near-bare-metal.

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wewtyflakes 13 hours ago | parent [-]

Wouldn't faster boot times mean that scale-out can be done on-demand? Whether this is preferable or not over poorer runtime performance is up to the domain, no?

	▲	ATechGuy 11 hours ago \| parent [-]
		When scaling out, edge latency will overshadow kernel boot-up times: speeding up boot-up from 1.5s to 150ms will not have any perceived impact on app performance when scaling on edge to meet the demand.