# etcd backend maintenance: compact, defrag, disarm NOSPACE.
#
# Why this exists
# ---------------
# etcd's backend file only grows. The apiserver compacts every 5m, but
# compaction marks superseded revisions free *inside* the file; only `defrag`
# returns that space to the filesystem. Nothing ran defrag, so the file grew
# until it crossed the 2 GiB quota:
#
#   2026-10-07  backend 2,148,843,520 B (2.1 GB) on talos-cp-1 and talos-cp-3
#               -> etcd raised NOSPACE on those two members
#               -> etcd rejected ALL writes cluster-wide
#               -> kubelets could not post node status: 3 nodes NotReady
#               -> apiserver writes returned 500, the tunnel API path 502
#
# The live data was tiny: 15,943 keys, 69 MB after compaction. The rest was
# dead pages. Recovery was `compact <current-revision>` then `defrag` per
# member then `alarm disarm`. Compaction had also stalled while the alarm was
# up, so `dbSizeInUse` read 100% of the file - defrag alone would NOT have
# worked. Order matters: compact first, then defrag.
#
# The earlier revision of this file never ran, for two independent reasons:
#   1. it existed only on branch fix/etcd-defrag-cron; the ArgoCD application
#      `cluster-maintenance` tracks `main` (targetRevision: main), so the
#      cluster never had the CronJob or the Secret.
#   2. the image was quay.io/coreos/etcd, which has NO /bin/sh (verified:
#      `exec: "/bin/sh": no such file or directory`). Any container that runs
#      a shell script needs an image that ships one.
# This revision fixes both: image bitnamilegacy/etcd (ships bash + etcdctl
# 3.6.4, matching the 3.6.11 servers) pinned by digest.
#
# Cadence: every 15 days. Measured growth is ~29 MB/day, so a 15-day cycle
# peaks near 500 MB - comfortably under the 2 GiB quota. The schedule is daily
# and the script exits unless the UTC epoch day is a multiple of 15. That gives
# an exact 15-day interval; `*/15` in the day-of-month field does not (it fires
# on the 1st, 16th and 31st, which puts two runs one day apart).
#
# Safety
# ------
# 1. Compaction uses the MINIMUM revision across members. Compacting to a
#    revision a member has not reached wedges that member - measured on
#    2026-10-07, when talos-cp-2 froze ~1.2M entries behind the leader and
#    needed a reboot to rejoin.
# 2. A member whose raft applied index lags the leader by more than 100000 is
#    skipped and reported. Defragging a frozen member reclaims nothing.
# 3. Members are defragged one at a time. A defrag pauses the member's apply
#    loop for the duration of the file copy.
#
# Credentials: Secret etcd-defrag-creds in kube-system, SOPS-managed in
# k8s/argocd/secrets/etcd-defrag-creds.enc.yaml (ksops generator 00-secrets).
# Its client certificate is signed by the cluster's etcd CA and expires
# 2036-10; rotate it before then by re-running the mint and re-encrypting.
#
# Companion alerts (monitoring): etcd_mvcc_db_total_size_in_bytes /
# etcd_server_quota_backend_bytes > 0.8, and an etcd NOSPACE alarm alert.
apiVersion: batch/v1
kind: CronJob
metadata:
  name: etcd-defrag
  namespace: kube-system
  labels:
    app.kubernetes.io/name: etcd-defrag
    app.kubernetes.io/part-of: cluster-maintenance
spec:
  schedule: "0 3 * * *"            # daily; the script acts only every 15th day
  concurrencyPolicy: Forbid
  startingDeadlineSeconds: 600
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 3
  jobTemplate:
    spec:
      backoffLimit: 2
      template:
        spec:
          restartPolicy: OnFailure
          tolerations:
            - key: node-role.kubernetes.io/control-plane
              operator: Exists
              effect: NoSchedule
          containers:
            - name: defrag
              image: bitnamilegacy/etcd:3.6.4@sha256:c86c06f1ce6a08b6df21eb7a9655b1818778b64c85b5cbb8413ebf7534789730
              env:
                - name: ETCDCTL_API
                  value: "3"
                - name: ETCDCTL_CACERT
                  value: /etc/etcd/ca.crt
                - name: ETCDCTL_CERT
                  value: /etc/etcd/client.crt
                - name: ETCDCTL_KEY
                  value: /etc/etcd/client.key
                - name: EPS
                  value: "https://192.168.1.166:2379 https://192.168.1.214:2379 https://192.168.1.162:2379"
              command: ["/bin/bash", "-c"]
              args:
                - |
                  set -u

                  DAY=$(( $(date -u +%s) / 86400 ))
                  if [ $(( DAY % 15 )) -ne 0 ]; then
                    echo "skip: UTC epoch day $DAY is not a 15-day boundary"
                    exit 0
                  fi

                  echo "== before =="
                  for ep in $EPS; do
                    etcdctl --endpoints="$ep" endpoint status -w table || true
                  done

                  MINREV=""
                  MAXAPPLIED=0
                  for ep in $EPS; do
                    json=$(etcdctl --endpoints="$ep" endpoint status -w json 2>/dev/null) || continue
                    rev=$(printf '%s' "$json" | sed -n 's/.*"revision":\([0-9]*\).*/\1/p' | head -1)
                    app=$(printf '%s' "$json" | sed -n 's/.*"raftAppliedIndex":\([0-9]*\).*/\1/p' | head -1)
                    echo "member $ep revision=${rev:-?} raftAppliedIndex=${app:-?}"
                    if [ -n "$rev" ] && { [ -z "$MINREV" ] || [ "$rev" -lt "$MINREV" ]; }; then
                      MINREV="$rev"
                    fi
                    if [ -n "$app" ] && [ "$app" -gt "$MAXAPPLIED" ]; then
                      MAXAPPLIED="$app"
                    fi
                  done

                  if [ -z "$MINREV" ]; then
                    echo "FATAL: no member returned a revision; nothing attempted"
                    exit 1
                  fi

                  echo "== compact to revision $MINREV =="
                  etcdctl --endpoints="$(echo "$EPS" | awk '{print $1}')" compact "$MINREV" || echo "COMPACT-FAILED (continuing: defrag still reclaims free pages)"

                  # Physical deletion of superseded keys runs in the background
                  # after the compaction commit; give it a moment to drain.
                  sleep 20

                  echo "== defrag each member (sequential, one at a time) =="
                  rc=0
                  for ep in $EPS; do
                    json=$(etcdctl --endpoints="$ep" endpoint status -w json 2>/dev/null) || { echo "SKIP $ep (unreachable)"; rc=1; continue; }
                    app=$(printf '%s' "$json" | sed -n 's/.*"raftAppliedIndex":\([0-9]*\).*/\1/p' | head -1)
                    if [ -n "$app" ] && [ "$app" -lt $(( MAXAPPLIED - 100000 )) ]; then
                      echo "SKIP $ep (applied index $app lags leader $MAXAPPLIED; defrag would reclaim nothing)"
                      rc=1
                      continue
                    fi
                    echo "-- $ep"
                    if ! etcdctl --endpoints="$ep" defrag; then
                      echo "DEFRAG-FAILED $ep"
                      rc=1
                    fi
                  done

                  echo "== disarm NOSPACE =="
                  for ep in $EPS; do
                    etcdctl --endpoints="$ep" alarm list 2>/dev/null || true
                    etcdctl --endpoints="$ep" alarm disarm 2>/dev/null || true
                  done

                  echo "== after =="
                  for ep in $EPS; do
                    etcdctl --endpoints="$ep" endpoint status -w table || true
                  done
                  etcdctl --endpoints="$(echo "$EPS" | awk '{print $1}')" alarm list || true
                  exit $rc
              resources:
                requests: { cpu: 10m, memory: 32Mi }
                limits:   { cpu: 200m, memory: 128Mi }
              volumeMounts:
                - name: creds
                  mountPath: /etc/etcd
                  readOnly: true
          volumes:
            - name: creds
              secret:
                secretName: etcd-defrag-creds
                defaultMode: 0444