apiVersion: v1
kind: ConfigMap
metadata:
  name: ddns-script
  namespace: monitoring
data:
  ddns.sh: |
    #!/bin/sh
    # Keeps the carr.pub apex A record pointing at this network's public IP.
    RECORD_ID=84723206
    ZONE="carr.pub"
    ACCOUNT=6300
    API="https://api.dnsimple.com/v2"
    AUTH="Authorization: Bearer ${DNSIMPLE_TOKEN}"

    IP=$(curl -s -m 15 https://ifconfig.me)
    case "$IP" in
      *.*.*.*) : ;;
      *) echo "no valid public ip: '$IP'"; exit 0 ;;
    esac

    CUR=$(curl -s -m 15 -H "$AUTH" "$API/$ACCOUNT/zones/$ZONE/records/$RECORD_ID" \
      | sed -n 's/.*"content":"\([^"]*\)".*/\1/p')
    if [ "$IP" = "$CUR" ]; then
      echo "$(date -Is) up to date ($IP)"
      exit 0
    fi

    RES=$(curl -s -m 15 -X PATCH -H "$AUTH" -H "Content-Type: application/json" \
      "$API/$ACCOUNT/zones/$ZONE/records/$RECORD_ID" \
      -d "{\"content\":\"$IP\"}")
    echo "$(date -Is) updated carr.pub -> $IP"
    case "$RES" in
      *'"id"'*) exit 0 ;;
      *) echo "API error: $RES"; exit 1 ;;
    esac
---
apiVersion: batch/v1
kind: CronJob
metadata:
  name: ddns-carr-pub
  namespace: monitoring
spec:
  schedule: "*/5 * * * *"
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 1
  failedJobsHistoryLimit: 3
  jobTemplate:
    spec:
      backoffLimit: 1
      template:
        spec:
          restartPolicy: Never
          containers:
            - name: ddns
              image: curlimages/curl:8.11.1
              command: ["/bin/sh", "/scripts/ddns.sh"]
              env:
                - name: DNSIMPLE_TOKEN
                  valueFrom:
                    secretKeyRef: {name: dnsimple-token, key: token}
              resources:
                requests: {cpu: 10m, memory: 16Mi}
                limits: {memory: 32Mi}
              volumeMounts:
                - {name: scripts, mountPath: /scripts}
          volumes:
            - name: scripts
              configMap: {name: ddns-script, defaultMode: 0744}