Benjamin Elder
cb72d60bdf
This is the companion to #496 In order to grant access to `/dev/kvm` we have to either: - use a device plugin - use a DRA driver - use an NRI plugin An NRI plugin is highly privileged in it's own right for all pods on the host and is difficult to ship portably at the moment. DRA is promising, but not enough functionality is GA yet at our current 1.35+ target. Device plugin fits reasonably well. We do wind up publishing an ~arbitrarily high limit, which has some cost in kubelet memory, but otherwise is relatively clean. This approach is what kata uses currently. Their device plugin is not available unbundled, and we anyhow have a per-node daemonset. atlet is taught to sniff if /dev/kvm appears on the host at all, so we can also stop using the manually labeled nodes for microVM class and instead schedule to the KVM + TUN devices on nodes that advertise them. Later we can migrate to device plugin by using I implemented that already, but I don't think it's worth merging at the moment. We would want consumable capacity to be on by default. We can migrate later without changing the pod spec by using `extendedResourceName`. https://github.com/agent-substrate/substrate/compare/main...BenTheElder:substrate:ateom-microvm-dra NOTE: I confirmed with upstream that device plugin is not going anywhere despite being "v1beta1", it's GA in all but name. It won't receive new features but we don't really need anyhow. We'll move to DRA down the line. --- By doing this, we can drop `privileged: true` from the uVM ateom pods. We can also drop the `ate.dev/sandboxClass` node label hacks, reducing friction to deploy.
procfs
This package provides functions to retrieve system, kernel, and process metrics from the pseudo-filesystems /proc and /sys.
WARNING: This package is a work in progress. Its API may still break in backwards-incompatible ways without warnings. Use it at your own risk.
Usage
The procfs library is organized by packages based on whether the gathered data is coming from
/proc, /sys, or both. Each package contains an FS type which represents the path to either /proc,
/sys, or both. For example, cpu statistics are gathered from
/proc/stat and are available via the root procfs package. First, the proc filesystem mount
point is initialized, and then the stat information is read.
fs, err := procfs.NewFS("/proc")
stats, err := fs.Stat()
Some sub-packages such as blockdevice, require access to both the proc and sys filesystems.
fs, err := blockdevice.NewFS("/proc", "/sys")
stats, err := fs.ProcDiskstats()
Package Organization
The packages in this project are organized according to (1) whether the data comes from the /proc or
/sys filesystem and (2) the type of information being retrieved. For example, most process information
can be gathered from the functions in the root procfs package. Information about block devices such as disk drives
is available in the blockdevices sub-package.
Building and Testing
The procfs library is intended to be built as part of another application, so there are no distributable binaries.
However, most of the API includes unit tests which can be run with make test.
Updating Test Fixtures
The procfs library includes a set of test fixtures which include many example files from
the /proc and /sys filesystems. These fixtures are included as a ttar file
which is extracted automatically during testing. To add/update the test fixtures, first
ensure the testdata/fixtures directory is up to date by removing the existing directory and then
extracting the ttar file using make testdata/fixtures/.unpacked or just make test.
rm -rf testdata/fixtures
make test
Next, make the required changes to the extracted files in the testdata/fixtures directory. When
the changes are complete, run make update_fixtures to create a new fixtures.ttar file
based on the updated fixtures directory. And finally, verify the changes using
git diff testdata/fixtures.ttar.