# observability patches

Strategic-merge patches applied on top of Helm-managed observability
resources. Each file is idempotent (re-applying is a no-op) and is
reasserted by hand rather than by a controller, so re-run after any
`helm upgrade` of the affected release.

## `node-exporter-textfile-collector.yaml` (DEV-494)

Enables the node-exporter textfile collector on the
`kube-prometheus-stack-prometheus-node-exporter` DaemonSet by:

1. adding `--collector.textfile.directory=/host/textfile_collector`
   to the container args, and
2. mounting the host directory `/var/lib/node_exporter/textfile_collector`
   read-only at `/host/textfile_collector` (`hostPath` type
   `DirectoryOrCreate`, kubelet creates it on nodes where the
   directory does not exist yet).

The four monitoring backup CronJobs in `apps/monitoring/` write their
textfile-collector `.prom` files into that same host directory, so the
metrics surface in Prometheus via node-exporter's normal scrape.

Apply / re-apply:

```bash
kubectl -n observability patch daemonset \
  kube-prometheus-stack-prometheus-node-exporter \
  --type=strategic \
  --patch-file=apps/observability/patches/node-exporter-textfile-collector.yaml
kubectl -n observability rollout status daemonset \
  kube-prometheus-stack-prometheus-node-exporter
```

The kube-prometheus-stack chart is not currently tracked in ArgoCD;
if it moves under GitOps, fold these values into the chart values as
`prometheus-node-exporter.extraArgs` + `.extraHostVolumeMounts`
instead of maintaining this patch.