atlas-iac/docs/CLUSTER_OPERATIONS.md

# Running Atlas without an AI assistant

Start here for ordinary operation. The repository describes desired state;
Kubernetes and Flux apply it. The [implementation record](CLUSTER_STABILIZATION.md)
separates completed repairs from open problems. The
[service inventory](cluster-audit-20261002/SERVICE_PLAN.md) covers the whole cluster.

## The small map

| Concern | Owner and configuration | What it does |
| --- | --- | --- |
| Desired Kubernetes configuration | Flux; `clusters/atlas/flux-system/` | Tracks `main`, applies service and infrastructure folders |
| Normal pod replacement and scheduling | Kubernetes; each workload manifest | Restarts failed containers and schedules replacements within placement and resource constraints |
| Application deployment | `services/<name>/`, or `infrastructure/<name>/` for foundations | Images, resources, probes, storage and networking |
| Durable application disks | Longhorn; `infrastructure/longhorn/` | Replication and volume attachment; not an application-consistent database backup by itself |
| Kubernetes datastore recovery | Native PostgreSQL tools and systemd on titan-db and titan-0b | Hourly protected LAN recovery bundles, independent of Kubernetes |
| Application PostgreSQL recovery | `atlas-application-postgres-backup.timer` on titan-0b; `infrastructure/host-backup/` | Daily logical database dumps with checksums, kept on the approved LAN host |
| Application backup orchestration | Soteria; `services/maintenance/apps/soteria-*` | Applies eligible-data policies through the chosen storage backend |
| Power loss and exceptional node recovery | Ananke; host configuration and `scripts/ops/cluster_power_*` | Orders shutdown/startup and bounded node recovery; it does not replace storage or database recovery |
| Node build/configuration | Metis and its sentinels; `services/maintenance/` | Approved node provisioning and host configuration |
| CI fault handling | Ariadne; `services/maintenance/apps/ariadne-*` | Bounded CI diagnosis/recovery; core cluster health must not depend on model calls |
| Health evidence | Grafana, VictoriaMetrics, Alertmanager; `services/monitoring/` | Shows application, node and storage evidence; a green controller alone is insufficient |

There is no new coordinating framework to learn. Prefer the native owner above.
Use a recovery tool only when its documented operation matches the failure.

The first priority is steady service operation. Repair recurring restarts and
storage pressure before adding workload or upgrading the platform. Keep known
unstable nodes quarantined; retain recovery copies and verify application health.
CI may queue when compatible capacity is unavailable. That is an explicit
capacity problem to repair, not a reason to overcommit the storage workers.

## Node administrative access

From the management workstation, use the existing SSH aliases. Most nodes use
`atlas`; the exceptions are `titan-jh` (theia), `oceanus` (Titan-23, oceanus), and
`tethys` (Titan-24, tethys). The normal SSH port is 2277 through Titan-jh.

In Vault, open `kv/atlas/nodes/<hostname>`. For example,
`kv/atlas/nodes/titan-13` contains `atlas_password` for sudo and `root_password`
for the root account. Custom metadata now records `admin_username`,
`admin_access_method`, `admin_access_verified_utc` and `root_password_state`.
Those are dated audit results, not a continuously updated health guarantee.

A normal manual check is:

```bash
ssh titan-13
sudo -k
sudo -v
sudo id -u
sudo passwd -S root
```

Enter the node's atlas password at the sudo prompt; never put it into the shell
command or a shared log. UID 0 proves administrator access. Some original nodes
already have passwordless sudo; this work did not add such grants. Nine native
Ubuntu accounts retain a locked direct root login; use their administrator and
sudo. A nonempty Vault root_password field alone does not prove root login works.

For scoped repair, `scripts/node_admin_access.py` runs on the target as root and
accepts a hostname plus password mapping on stdin. It compares password hashes
locally, reports only booleans, and changes passwords only with `--apply`.
`--retire-legacy-sudo` removes only the two recognized historical Metis grants
after password verification, preserving a root-only rollback copy. Do not run
that migration before independently testing password-backed sudo.

Keep SSH host-key verification enabled. Titan-09/10 currently answer on port 22
with changed keys; their reinstall identity must be established before sending
passwords. Titan-05 answers ping but has no tested admin listener. Titan-06/16
did not answer the current LAN checks. See the dated implementation record.

Metis source now provisions a native one-shot identity service instead of
relying exclusively on cloud-init. After a future recovery, check the unit,
verify its pending marker cleared, then test a separate SSH/sudo session before
returning the node to Kubernetes service. Image publication and a real replacement
boot remain separate acceptance checks; do not assume a source commit is deployed.

Ananke's allowlisted host actions can now obtain the atlas password through the
existing CSI synchronization, configured in
`services/maintenance/bootstrap/secretproviderclass.yaml`. The synchronized
Secrets are named `maintenance/ananke-sudo-<hostname>`, with key `password`.
Only the 13 verified workers needing that path are included; root passwords
remain in Vault. The CSI driver refreshes them every two minutes.

The two native Ananke configurations use:

```yaml
startup:
  host_sudo_secret_namespace: maintenance
  host_sudo_secret_name_template: "ananke-sudo-{node}"
  host_sudo_secret_password_key: password
```

These are fields within the existing startup section, not a replacement config.
`scripts/configure_ananke_node_access.py` applies that narrow change, validates it
with Ananke, and retains a root-only backup. The coordinator remains Titan-db;
Titan-24 remains its peer. Credentials go to sudo stdin for predefined actions,
not arbitrary command arguments or logs. No new controller was introduced.

The peer's public key must also be present in the worker's atlas authorized_keys.
It is recorded in `kv/atlas/maintenance/metis-ssh-keys`, field `ananke_tethys_pub`.
`scripts/install_ananke_peer_key.py` accepts a hostname and verified public key on
stdin, preserves existing keys, and restricts new entries to Titan-24's source
address 192.168.22.26. It grants no sudo permissions. Verify the public key through
an already authenticated connection; never replace trusted host keys just to
make SSH connect. On October 4, both the coordinator and peer passed actual
privileged read-only worker checks after this repair.

This automated worker-password path requires the Kubernetes API. It is not a
standalone cold-start credential store. A read-only access check is not a power
failure/recovery drill. When onboarding another recovered worker, first validate
its Vault password and SSH identity, then add its explicit CSI mapping.

## Automatic recovery that can change services

Ananke's coordinator runs as `ananke.service` on Titan-db; its settings are in
`/etc/ananke/ananke.yaml`, with installed source in `/opt/ananke`. Titan-24 is
the UPS peer. Only the coordinator runs periodic cluster repair. UPS monitoring
is a separate responsibility within the same daemon: do not stop that daemon
casually to troubleshoot a Kubernetes helper.

The credential-helper repair checks every 60 seconds but acts only on a current
pod with an active image-pull failure and a matching warning less than ten
minutes old. It records an attempt before restarting a helper and allows at
most one attempt per helper per 30 minutes, across daemon restarts. Old events
and warnings for replaced pods do not justify another restart. Check helper
generation and Ananke's journal when investigating unexpected rollouts:

```bash
kubectl -n jenkins get deployment jenkins-vault-sync
ssh titan-db sudo journalctl -u ananke --since '10 minutes ago' --no-pager
ssh titan-db systemctl status ananke-update.timer
```

The native updater now preserves the running binary when its quality gate
fails. A binary-only maintenance install also preserves host/NUT configuration
and retains the prior binary for rollback. Read `scripts/install.sh` in the
Ananke repository before updating; `--binary-only --skip-deps` is the targeted
path, while the normal updater also applies host configuration templates.

Ariadne's `ARIADNE_HERMES_HUNG_BUILD_MINUTES` setting is in
`services/maintenance/apps/ariadne-deployment.yaml`. It is currently zero, which
disables elapsed-time-only cancellation. Its retained event confirmed that the
previous 120-minute setting canceled an active Metis image build. Other bounded
diagnosis/repair remains enabled. Do not re-enable cancellation until it can
distinguish a stalled job from a long-running job making useful progress.

Jenkins's Kubernetes cloud cap is currently one in
`services/jenkins/configmap-jcasc.yaml`. The shared default, IaC, Data Prepper and
Metis templates exclude quarantined nodes and storage workers. Custom inline
templates in other repos may need the same correction. Inspect actual agent
placement rather than assuming the default template controls every pipeline.
A Pending agent consumes the cap; inspect FailedScheduling events and resource
requests before deciding that Jenkins is hung. Do not increase concurrency to
solve an unschedulable agent. The tracked JCasC revision triggers a controller
rollout, so quiet the queue and arrange active-build completion before editing.

Node quarantine is declared in `infrastructure/core/node-maintenance.yaml`.
Those Node resources explicitly preserve hardware/worker/storage labels and use
Flux SSA Merge to retain other runtime fields. A cordon blocks ordinary new
placement; it must not repeatedly remove existing storage DaemonSets. After a
quarantine change, verify manager pod UIDs stay unchanged across reconciliation.
Keep prune protection on Node declarations; repair, uncordon in Git and verify
before considering their removal.

## Five-minute check

Run from the management host with the existing administrator configuration:

```bash
kubectl get nodes -o wide
flux get kustomizations -A
flux get helmreleases -A
kubectl get deployments,statefulsets -A
kubectl get pods -A --field-selector=status.phase=Pending
kubectl -n longhorn-system get volumes.longhorn.io
```

Then check the affected service's health endpoint or UI. `Running` does not mean
ready; `Ready` does not prove useful application behavior. A detached Longhorn
volume may be intentional if its workload is parked. Distinguish that from an
attached volume that is faulted or an application waiting for its disk.

Check the control-plane backups separately:

```bash
ssh titan-db sudo systemctl status atlas-k3s-backup.timer
ssh titan-0b sudo systemctl status atlas-k3s-replica.timer
ssh titan-db sudo cat /var/backups/atlas-k3s/latest/COMPLETE
ssh titan-0b sudo cat /var/backups/atlas-k3s-replica/latest/COMPLETE
```

`COMPLETE` contains timestamps, not database contents. The backup and replica
should normally be less than two hours old. Check the last service result too:

```bash
ssh titan-db sudo systemctl show atlas-k3s-backup.service -p Result -p ExecMainStatus
ssh titan-0b sudo systemctl show atlas-k3s-replica.service -p Result -p ExecMainStatus
```

Application database backups run separately each day at 08:15 UTC plus up to
five minutes of jitter. Check their timer and completion timestamp too:

```bash
ssh titan-0b sudo systemctl status atlas-application-postgres-backup.timer
ssh titan-0b sudo cat /var/backups/atlas-postgres/latest/COMPLETE
```

Their freshness alert fires after 36 hours. See the host backup notes before
running the isolated restore verification or changing retention.

## Find the cause before choosing a repair

| Symptom | First check | Usual next action |
| --- | --- | --- |
| Node NotReady | Power/network, kubelet status, disk space, pressure | Repair/quarantine the node; do not repeatedly restart every application |
| Pod Pending / FailedScheduling | `kubectl describe pod` scheduling events | Correct resource requests or eligible capacity; free cluster-wide RAM does not guarantee a compatible destination |
| ContainerCreating / FailedMount | PVC, Longhorn volume, attachment and engine events | Preserve data; repair the attachment or use a verified healthy node. Do not delete the PVC |
| CrashLoopBackOff / OOMKilled | Previous container logs and last termination reason | Fix the application or its resource envelope; lifetime restart counts are not a reason for repeated eviction |
| Ingress 502/503 | Service endpoints and backend readiness | Restore the backend or its dependency before changing DNS/TLS |
| Flux Ready but missing Helm workload | Helm manifest and drift correction | Check that drift detection is enabled and suitable for that release |
| All cluster API operations fail | titan-db PostgreSQL and control-plane nodes | The datastore is external PostgreSQL; an etcd snapshot procedure will not restore it |
| CI waiting while applications work | Jenkins queue, agent capacity and node I/O | Let work queue; adding agents to saturated Pi disks makes both CI and services worse |

Useful scoped commands:

```bash
kubectl -n NAMESPACE describe pod POD
kubectl -n NAMESPACE get events --sort-by=.lastTimestamp
kubectl -n NAMESPACE get endpointslices
kubectl -n NAMESPACE logs POD -c CONTAINER --previous --tail=80
```

Application logs can contain private data. Inspect them locally and redact before
sharing. Never paste Secrets, tokens, source records or inference bodies into a
ticket or assistant conversation.

## Make a normal change

1. Edit the service's tracked manifest. Placement, requests, limits and probes
   belong together in that workload's configuration.
2. Render and validate the affected folder; inspect the Flux preview.
3. Commit and push a small change to the tracked branch.
4. Reconcile that service and verify its application behavior and storage.

For example:

```bash
kubectl kustomize services/monitoring > /tmp/monitoring-render.yaml
kubectl apply --dry-run=client -k services/monitoring
flux diff kustomization monitoring --path services/monitoring
git diff --check
git diff
```

After committing and pushing the reviewed files:

```bash
flux reconcile kustomization monitoring -n flux-system --with-source
kubectl -n monitoring get deployments,statefulsets,pods
```

A Flux diff exits nonzero when it finds changes; read the output to distinguish
that from a validation failure. Kustomize renders a HelmRelease, not the chart's
workloads. For chart values, also inspect the chart's rendered Deployment or
StatefulSet. OpenSearch, for example, uses `values.nodeAffinity`.

Rollback a configuration change by reverting its focused commit and reconciling
the same service. Do not blindly revert storage migrations or database changes;
those require their recovery procedure. Do not delete data to clear a red status.

## Backups and recovery

The external datastore's [host backup notes](../infrastructure/host-backup/NOTES.md)
give the actual paths, schedule, credential scope, isolated restore check and
rollback. Backups contain sensitive data and remain root-only on approved LAN
hosts. They are not encrypted at rest or off-site disaster recovery copies.

Soteria is responsible for eligible application backups, not for making the
control plane boot. Live Longhorn snapshots and database-native dumps offer
different consistency guarantees. A recent backup indicator is not a restore
test. Keep database restore checks and service recovery drills explicit.

For cloud backups, inspect completed backup timestamps, not just the backup
target's Available status or a successful bucket listing. The October 3 audit
found a readable Backblaze bucket rejecting uploads with `storage cap exceeded`.
Check Backblaze Caps & Alerts and agree the storage budget before changing it.
Do not delete old recovery points merely to make uploads work. Distinguish
visible-object bytes from billed storage, including retained versions. The
current diagnosis and counts are in the implementation record.

The Hermes namespace is excluded from cloud backup policy. Its workspaces can
contain material restricted to local infrastructure. Do not remove that exclusion
to make a coverage dashboard greener.

## A one-day familiarization exercise

* Morning: follow one application from its Flux definition to its workload,
  storage, service and ingress. Compare those manifests with live objects.
* Before lunch: inspect one scheduling incident and one storage incident using
  the table above. Identify the responsible component without changing anything.
* Afternoon: run the isolated datastore restore verification, inspect backup
  timestamps, then make and revert a harmless configuration change through Flux.
* Finish by finding each remaining issue in the implementation record and the
  corresponding owner/runbook. Confirm access to Git, the management host, the
  hosts' SSH path and protected recovery material without relying on SSO alone.

This provides a practical route to ownership; it cannot promise that every
hardware, storage or database disaster will be solvable in one day.

## Physical checks and return to service

For an offline Pi, record the board identity, supply model and its 5 V rating,
power/activity LEDs, HDMI boot result, Ethernet link and current router address.
Preserve the original SD/USB media. Test with separate known-good spare boot media
before concluding that a board has failed; do not clone a live node identity by
moving another cluster node's boot card into it.

Pi 5 power must be evaluated at its 5 V output mode, not a charger's headline
wattage. A controlled supply-and-cable substitution isolates the power path.
Record any inline adapters and USB loads. Do not unplug runtime USB storage on
a running node. Titan-11 carries important services; arrange workload movement
before disconnecting it. See the official Raspberry Pi power documentation for
5 V / 5 A capability and cable-loss requirements.

A repaired node returns only after stable power, clean storage/kernel logs,
reliable networking and representative-load testing. Observe it before restoring
normal placement. Titan-14/18 quarantine is explicitly tracked in
`infrastructure/core/node-maintenance.yaml`; `prune: disabled` protects the Node
objects from deletion when that maintenance declaration is eventually removed.
Clear `spec.unschedulable` through Git after validation, then reconcile core.

Container runtime media and Longhorn data disks are separate. A Pi with terabytes
of healthy application storage can still stall because containerd, image unpacking
and logs live on a small USB flash device. Include the runtime disk in hardware
repair and capacity checks.