External VictoriaMetrics / cluster

By default DumbMonit starts its own VictoriaMetrics inside the container. You can point it at one you run yourself instead.

When it makes sense

• More than about 5 000 monitors (see Sizing).
• High availability, or storage on its own host or disk.
• You already run VictoriaMetrics and want one place for retention, backups and monitoring.
• You want to read DumbMonit’s series from Grafana or other tools too.

For a homelab or a small team the embedded one is simpler and needs nothing.

Single-node instance

    environment:
      DUMBMONIT_VM_URL: http://victoriametrics:8428

DumbMonit writes to <URL>/api/v1/import/prometheus and reads from <URL>/api/v1/query, query_range, series and label/…. Nothing else is needed on the VictoriaMetrics side; its series are prefixed dumbmonit_, so it can be shared.

When DUMBMONIT_VM_URL is set, the embedded VictoriaMetrics is not started and /data/vm stays empty. GET /api/health reports victoria.embedded: false.

What changes

• Retention is managed on the external instance (-retentionPeriod). In Settings → System the raw-retention field becomes read-only.
• Memory (DUMBMONIT_VM_MEMORY) and the listen address do not apply: size the external instance yourself.
• Deleting series (when you remove a monitor or clean up) calls /api/v1/admin/tsdb/delete_series. Single-node VictoriaMetrics allows it by default; a -deleteAuthKey on the instance makes DumbMonit’s call fail, the rest keeps working and the series simply age out.
• Backups: the DumbMonit backup no longer covers metrics. Back the instance up with vmbackup or the volume snapshots of your platform.
• The server buffers samples and retries when the instance is down, within the limits of its in-memory buffer; a long outage loses data.

Cluster (vminsert / vmselect)

A VictoriaMetrics cluster serves writes and reads on different services and under tenant paths:

Operation	Cluster URL
Write	http://vminsert:8480/insert/0/prometheus/api/v1/import/prometheus
Read	http://vmselect:8481/select/0/prometheus/api/v1/query_range

DumbMonit builds every URL as DUMBMONIT_VM_URL + /api/v1/…, and a single URL must serve both writes and reads. It therefore cannot talk to vminsert and vmselect directly. Put vmauth in front and route by path:

# vmauth config (-auth.config)
unauthorized_user:
  url_map:
    - src_paths: ["/api/v1/import/.*"]
      url_prefix: "http://vminsert:8480/insert/0/prometheus/"
    - src_paths: ["/api/v1/admin/tsdb/delete_series"]
      url_prefix: "http://vmselect:8481/delete/0/prometheus/"
    - src_paths: ["/api/v1/(query|query_range|series|labels|label/.*|export)"]
      url_prefix: "http://vmselect:8481/select/0/prometheus/"

Then DUMBMONIT_VM_URL: http://vmauth:8427. Keep vmauth on a private network, or give it users: with credentials; a shared secret in the URL is stored in the environment of the container, so treat it like any other secret. Tenant 0 is only an example: use the account id you want.

Long-term store

The 5-minute aggregates live in a second VictoriaMetrics. With the embedded setup it is started for you under /data/vm-long. With an external main instance there is none unless you name one:

    environment:
      DUMBMONIT_VM_URL: http://victoriametrics:8428
      DUMBMONIT_VM_LONG_URL: http://victoriametrics-long:8428

Use a separate instance (or tenant behind vmauth, same routing as above): the aggregates use the same metric names as the raw data, plus :5m_min, :5m_max, :5m_sum and :5m_count suffixes, and their retention (730 days by default) differs from the raw one. Set -retentionPeriod on that instance accordingly. Without DUMBMONIT_VM_LONG_URL, an external main instance means no long-term history: Settings → System says so, and graphs are limited to the retention of the external instance.

Setting DUMBMONIT_VM_LONG_URL with the embedded main instance also works: the embedded long-term store is then not started.