Disk usage, object counts and quota alerts come exclusively from Prometheus — without it, bandwidth billing still works but there are no storage figures and no 90% quota alert emails. This article sets up the scrape and connects it to Blesta.

How the pieces fit

1. Your storage server (MinIO or RustFS) exposes per-bucket usage metrics on a MinIO-compatible metrics v3 endpoint.
2. Prometheus scrapes that endpoint on a schedule and stores the series.
3. The Usage Billing plugin queries the Prometheus API hourly for two instant values per bucket: minio_cluster_usage_buckets_total_bytes and minio_cluster_usage_buckets_objects_count, filtered by bucket name and your job name.

Step 1 — the scrape job

Generate a metrics bearer token with the mc client against your server alias:

mc admin prometheus generate YOUR_ALIAS cluster

Add a job to your prometheus.yml (job_name is your choice — you will enter the same value in Blesta):

- job_name: minio-job-bucket
  metrics_path: /minio/metrics/v3/cluster/usage/buckets
  scheme: https
  bearer_token: PASTE_TOKEN_FROM_mc_admin_prometheus_generate
  static_configs:
    - targets: ['your-storage-host:443']

Reload Prometheus and confirm the target is UP on its Targets page, and that a query for minio_cluster_usage_buckets_total_bytes returns one series per bucket.

MinIO: works as-is (RELEASE with metrics v3). Tokens are stateless — generating a new one never invalidates the one Prometheus already uses; they only stop working if the server's root keys change.

RustFS: does not currently document a MinIO-compatible Prometheus metrics endpoint (native Prometheus support is an open item upstream). Until RustFS exposes /minio/metrics/v3/cluster/usage/buckets with the minio_cluster_usage_buckets_* metrics, disk figures and quota alerts are unavailable for RustFS-backed servers — treat this article as MinIO-specific. If a future RustFS release adds the compatible endpoint, the identical scrape job applies; verifying that the two metric names above return data is the only compatibility requirement the plugin has.

Step 2 — connect Blesta

On the module server row (Settings > Company > Modules > S3 Object Storage Provision Module (MinIO & RustFS) > Manage > Edit):

• Prometheus Host — base URL of the Prometheus API, e.g. http://10.0.0.5:9091.
• Prometheus Job — must match the job_name from step 1 exactly (mismatched job = "metric missing" failures).
• Prometheus User / Password — only if Prometheus itself sits behind basic auth; these are not storage-server credentials.

The same scrape example is shown inline on that form for copy-paste.

Troubleshooting

• Snapshots say storage source "missing" — Prometheus unreachable from the Blesta host, or the metric/job returned nothing. Check the plugin's failure message on the snapshot rows (S3 Usage > view a bucket).
• Numbers stuck / stale — the scrape target is DOWN (expired token, TLS issue) while Prometheus itself still answers. Fix the target; the next hourly pass recovers on its own.
• Quota alerts not firing — alerts only evaluate on successful Prometheus samples, so a broken scrape silently disables them. Same fix.
• Keep the scrape interval at 60s or faster than the 1-hour collection — the plugin reads instant values, so extremely sparse scrapes make months look emptier than they are.