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## What this PR does A SeaweedFS instance that runs out of room stops taking writes without anything paging. A volume server below its `minFreeSpacePercent` reserve turns every volume it holds read-only; before that, it can run out of slots, and a bucket whose volumes are all full then cannot get a new one, even with half the disk free. Backups archiving into the instance fail in turn, and a Postgres cluster doing continuous WAL archiving keeps the segments on its own volume until that fills too. The generic `KubePersistentVolumeFillingUp` alert does not catch this: it pages below 3% free, while a volume server stalls at its 5% reserve or, when slots run out, with the disk still half empty; and its early warning needs the disk to keep filling, which stops once writes fail. This PR adds per-instance rules to the SeaweedFS system chart, on signals the servers already publish and the platform already scrapes, rendered under the same `monitoring.enabled` gate as the chart's ServiceMonitors: - `SeaweedFSVolumeServerDiskLow` (warning): a volume server has less than 10% of its disk left above the reserve. - `SeaweedFSVolumeServerFull` (warning): a volume server cannot host another volume, because it is at the reserve or has no slot left. - `SeaweedFSWritesFailing` (critical): the master has failed to place a write in every 5-minute window for 15 minutes. Writes may still land in between; the usual cause is a bucket with no writable volume left that the master cannot grow. A new bucket's first writes fail a few picks while its volumes grow, which the 15-minute hold does not reach unless new buckets keep arriving. Every expression is pinned to the release namespace, because the root vmalert evaluates each instance's rules against every namespace's metrics. It also adds `docs/operations/seaweedfs-capacity-for-backups.md`: how to size an instance for continuous WAL archiving, what the rules mean, and how to grow an instance. The expressions were validated live rather than by unit tests, since the repository has no rule-evaluation tooling: on a test cluster, a standalone SeaweedFS 4.45 on a 1 GiB volume was scraped by the platform's vmagent and the rules rendered from this chart were evaluated by the root vmalert. All three loaded healthy and each reached `firing`: `SeaweedFSVolumeServerDiskLow` with 5.7% of the disk left above the reserve, `SeaweedFSVolumeServerFull` both at the reserve and on slot exhaustion, which stopped one bucket at 50% disk use, and `SeaweedFSWritesFailing` under continuous failing writes, resolving once they stopped. A new bucket's first successful writes on a free disk did fail a few picks, which is why that rule holds for 15 minutes. On the healthy platform instance all three stay quiet. helm-unittest pins what a render can break: the namespace selector of each rule, the shared label set of the two arms of the full-server rule, the gate, the critical rule's hold, and that alert templating reaches vmalert unrendered; each assertion was checked to fail when its line is mutated. ### Screenshots Not a UI change. ### Downstream repositories - [x] No downstream repository is affected by this change - [ ] [cozystack/website](https://github.com/cozystack/website) - follow-up: - [ ] [cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack) - follow-up: - [ ] [cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack) - follow-up: - [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up: - [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up: - [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) - follow-up: - [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) - follow-up: - [ ] [cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server) - follow-up: - [ ] [cozystack/external-apps-example](https://github.com/cozystack/external-apps-example) - follow-up: - [ ] [cozystack/examples](https://github.com/cozystack/examples) - follow-up: - [ ] [cozystack/community](https://github.com/cozystack/community) - follow-up: The diff touches a system chart template, its test and a document under `docs/operations/`; no app values, platform values, ApplicationDefinition, tooling or `hack/` path from the trigger map. ### Release note ```release-note feat(seaweedfs): alert when a SeaweedFS volume server nears its free-space reserve, cannot host another volume, or keeps failing to place writes, and document how to size an instance for continuous WAL archiving. ``` <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit - **New Features** - Added namespace-scoped SeaweedFS monitoring alerts for low or exhausted disk capacity, unavailable volume slots, and write-placement failures. Capacity alerts use a 10% disk threshold, and alerts trigger after 15 minutes; write failures are marked critical. - **Documentation** - Added guidance on estimating SeaweedFS storage needs for Postgres backups, interpreting capacity alerts, and expanding storage when supported by the StorageClass. <!-- end of auto-generated comment: release notes by coderabbit.ai -->