NFS mount not being scraped with hostmetrics reciever filesystem scraper.

[qsc-mattskogmo]

Hi all,
I am having an issue instrumenting a AI training machine with OTEL. 99.9% of it works, but I am having one last problem -- I cannot for the life of me figure out how to get the filesystem scraper to scrape the NFS mount.

I have otel-collector-contrib running in a container and a stupid simple config.yaml file to help me troubleshoot.

config.yaml:

receivers:
  hostmetrics:
    root_path: /hostfs
    collection_interval: 30s
    scrapers:
      filesystem:
        include_fs_types:
          fs_types: [nfs, nfs4]
          match_type: strict

exporters:
  debug:
    verbosity: detailed

service:
  pipelines:
    metrics:
      receivers: [hostmetrics] 
      exporters: [debug] 

Docker run:

docker run -d \
 --name otel-collector \
 --restart unless-stopped \
 --privileged \
 --pid host \
 --cgroupns host \
 --user 0:0 \
 --network bridge \
 -p 8889:8889 \
 -v /:/hostfs:ro,rslave \
 -v /data/otel-collector/otel-config.yaml:/etc/otelcol/config.yaml:ro \
 otel/opentelemetry-collector-contrib:latest \
 --config /etc/otelcol/config.yaml

I get zero metrics out.

2025-09-09T14:42:42.863Z	info	[email protected]/service.go:187	Setting up own telemetry...	{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}}

2025-09-09T14:42:42.910Z	info	[email protected]/service.go:249	Starting otelcol-contrib...	{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}, "Version": "0.133.0", "NumCPU": 256}

2025-09-09T14:42:42.910Z	info	extensions/extensions.go:41	Starting extensions...	{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}}

2025-09-09T14:42:42.910Z	info	[email protected]/service.go:272	Everything is ready. Begin running and processing data.	{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}}

2025-09-09T14:42:43.912Z	info	Metrics	{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}, "otelcol.component.id": "debug", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "resource metrics": 0, "metrics": 0, "data points": 0}

2025-09-09T14:42:43.912Z	info		{"resource": {"service.instance.id": "5032f2df-24d5-4d75-9f18-6c45b8dd2581", "service.name": "otelcol-contrib", "service.version": "0.133.0"}, "otelcol.component.id": "debug", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics"}

I know that the NFS is 'findable' both from command line (cat /proc/mounts) and by way of container:
I spun up a busybox/alpine with the exact same parameters as the docker run above and can successfully "see" the NAS.

docker run --rm -it --privileged -v /:/hostfs:ro,rslave alpine sh -c "apk add findmnt && findmnt -t nfs,nfs4 | grep -i remote"

OR
docker run --rm -it --pid host -v /:/hostfs:ro,rslave -v /proc:/hostfs/proc:ro -v /sys:/hostfs/sys:ro busybox sh -c "stat -f /hostfs/data_remote || echo statfs-failed"

I have run out of ideas -- please help! Thanks in advance.