Add RDMA collector

[yeahdongcn]

This PR collects RDMA stats using rdmamap.

Testing Done

1. docker run --pull=always --cap-add=SYS_TIME --net=host -it node-exporter-linux-amd64:master --collector.rdma --web.listen-address=:8864 --collector.disable-defaults
2. curl localhost:8864/metrics

The results can be viewed below:

metrics.log

Additionally, the above tests were performed on a node without RDMA devices. The node-exporter runs without issues, as shown in the following logs:

time=2024-11-08T11:18:18.441Z level=ERROR source=collector.go:168 msg="collector failed" name=rdma duration_seconds=4.3574e-05 err="no rdma devices found"

[fishingfly]

This looks super useful for GPU clusters.

[SuperQ]

I took a look at the new data reading library and I'm not very happy with it.

The main issue is this isn't setup to respect the sysPath and rootfsPath variables in paths.go. This means this collector will fail when running in a container when the host sysfs is remapped to a different path.

[yeahdongcn]

I took a look at the new data reading library and I'm not very happy with it.

The main issue is this isn't setup to respect the sysPath and rootfsPath variables in paths.go. This means this collector will fail when running in a container when the host sysfs is remapped to a different path.

@SuperQ Thank you for the review! I've updated the code as per your comments.

I'll also open an issue in rdmamap to see if the Dir paths can be moved to package variables for easier configuration (currently replaced with my fork).