Comment by upbeat_general
7 months ago
For a start, any suite that takes >X hours on a single node, especially compounded if you have a large team of developers.
> At least as long as you're running your own code on your own hardware
Assuming you keep a consistent env/OS across all nodes you will want to run said code. Which can be difficult, even just between two users on a single node.
Not to mention the fact that a lot of (most?) code needs to (A) interoperate with other people's code and (B) at least sometimes run on other hardware.
> For a start, any suite that takes >X hours on a single node, especially compounded if you have a large team of developers.
If your testing suite takes several hours to run on a 256 core server, and this is something you want to run on every commit by every dev, then you have a problem with your testing suite. Running it on k8s is just slapping a bandaid on it.
> Assuming you keep a consistent env/OS across all nodes you will want to run said code. Which can be difficult, even just between two users on a single node.
> Not to mention the fact that a lot of (most?) code needs to (A) interoperate with other people's code and (B) at least sometimes run on other hardware.
Yes, this is the problem that has been solved since the 90s by environment modules. This is how clusters and supercomputers work. There is no virtualization, just tcl and shell scripts.
Clusters and supercomputers are able to fully control the hardware & OS. environment modules are useful in that setting but do not solve OS differences, not to mention themselves need to be installed/maintained. lots of time developers do not work on your same cluster (say, for any open-source code) and environment differences can be significant.
I regularly use large clusters and even there docker/singularity are very helpful at times (very simple example, glibc requirements).
When you are talking about well-written code that only requires posix (and nothing beyond) and does not interface with hardware, etc. etc. then virtualization seems crazy.