apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: node-directory-size-metrics
  namespace: monitoring
  annotations:
    description: |
      This `DaemonSet` provides metrics in Prometheus format about disk usage on the nodes.
      The container `read-du` reads in sizes of all directories below /mnt and writes that to `/tmp/metrics`. It only reports directories larger then `100M` for now.
      The other container `caddy` just hands out the contents of that file on request via `http` on `/metrics` at port `9102` which are the defaults for Prometheus.
      These are scheduled on every node in the Kubernetes cluster.
      To choose directories from the node to check, just mount them on the `read-du` container below `/mnt`.
spec:
  selector:
    matchLabels:
      app: node-directory-size-metrics
  template:
    metadata:
      labels:
        app: node-directory-size-metrics
      annotations:
        prometheus.io/scrape: 'true'
        prometheus.io/port: '9102'
        description: |
          This `Pod` provides metrics in Prometheus format about disk usage on the node.
          The container `read-du` reads in sizes of all directories below /mnt and writes that to `/tmp/metrics`. It only reports directories larger then `100M` for now.
          The other container `caddy` just hands out the contents of that file on request on `/metrics` at port `9102` which are the defaults for Prometheus.
          This `Pod` is scheduled on every node in the Kubernetes cluster.
          To choose directories from the node to check just mount them on `read-du` below `/mnt`.
    spec:
      containers:
      - name: read-du
        image: giantswarm/tiny-tools:latest
        imagePullPolicy: Always
        command:
        - fish
        - --command
        - |
          touch /tmp/metrics-temp
          while true
            for directory in (du --bytes --separate-dirs --threshold=100M /mnt)
              echo $directory | read size path
              echo "node_directory_size_bytes{path=\"$path\"} $size" \
                >> /tmp/metrics-temp
            end
            mv /tmp/metrics-temp /tmp/metrics
            sleep 300
          end
        volumeMounts:
        - name: host-fs-var
          mountPath: /mnt/var
          readOnly: true
        - name: metrics
          mountPath: /tmp
      - name: caddy
        image: dockermuenster/caddy:0.9.3
        command:
        - "caddy"
        - "-port=9102"
        - "-root=/var/www"
        ports:
        - containerPort: 9102
        volumeMounts:
        - name: metrics
          mountPath: /var/www
      volumes:
      - name: host-fs-var
        hostPath:
          path: /var
      - name: metrics
        emptyDir:
          medium: Memory