Implement rootfs usage metrics (#1)

* Implement rootfs usage metrics

* Fix names in metric table

.drone.yml

@@ -0,0 +1,32 @@
+kind: pipeline
+type: kubernetes
+name: default
+
+steps:
+  - name: fetch
+    image: docker:git
+    commands:
+      - git fetch --tags
+
+  - name: docker-tag
+    image: alpine
+    commands:
+      - test "${DRONE_BRANCH}" == "master" && echo -n "latest," > .tags || true
+      - test -n "${DRONE_BRANCH}" && test "${DRONE_BRANCH}" != "master" && echo -n "${DRONE_BRANCH}," > .tags || true
+      - test -n "${DRONE_TAG}" && echo -n "${DRONE_TAG}," >> .tags || true
+      - sed -i "s/,$//" .tags
+
+  - name: docker-publish
+    image: plugins/docker
+    settings:
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+      repo: quay.io/utilitywarehouse/kube-summary-exporter
+      registry: quay.io
+
+trigger:
+  event:
+    exclude:
+      - pull_request

.gitignore

@@ -0,0 +1 @@
+kube-summary-exporter

Dockerfile

@@ -0,0 +1,13 @@
+FROM golang:1.15-alpine AS build
+WORKDIR /go/src/github.com/utilitywarehouse/kube-summary-exporter
+COPY . /go/src/github.com/utilitywarehouse/kube-summary-exporter
+ENV CGO_ENABLED 0
+RUN apk --no-cache add git &&\
+  go get -t ./... &&\
+  go test ./... &&\
+  go build -o /kube-summary-exporter .
+
+FROM alpine:3.12
+COPY --from=build /kube-summary-exporter /kube-summary-exporter
+
+ENTRYPOINT [ "/kube-summary-exporter"]

README.md

@@ -1 +1,38 @@
-# kube-stats-exporter
+# kube-summary-exporter
+
+[![Build Status](https://drone.prod.merit.uw.systems/api/badges/utilitywarehouse/kube-summary-exporter/status.svg)](https://drone.prod.merit.uw.systems/utilitywarehouse/kube-summary-exporter)
+
+Exports prometheus metrics for the Kubernetes Summary API.
+
+## Usage
+
+Visiting http://localhost:9779/node/example-node will return metrics for the
+node 'example-node'.
+
+Here's an example scrape config. This assumes that the exporter is available at `kube-summary-exporter:9779`.
+
+```
+  - job_name: "kubernetes-summary"
+    kubernetes_sd_configs:
+      - role: node
+    relabel_configs:
+      - action: labelmap
+        regex: __meta_kubernetes_node_label_(.+)
+      - source_labels: [__meta_kubernetes_node_name]
+        regex: (.+)
+        target_label: __metrics_path__
+        replacement: /node/${1}
+      - target_label: __address__
+        replacement: kube-summary-exporter:9779
+```
+
+## Metrics
+
+| Metric                           | Description                                           | Labels               |
+| -------------------------------- | ----------------------------------------------------- | -------------------- |
+| container_rootfs_inodes_free     | Number of available Inodes                            | pod, namespace, name |
+| container_rootfs_inodes          | Number of Inodes                                      | pod, namespace, name |
+| container_rootfs_inodes_used     | Number of used Inodes                                 | pod, namespace, name |
+| container_rootfs_available_bytes | Number of bytes that aren't consumed by the container | pod, namespace, name |
+| container_rootfs_capacity_bytes  | Number of bytes that can be consumed by the container | pod, namespace, name |
+| container_rootfs_used_bytes      | Number of bytes that are consumed by the container    | pod, namespace, name |

go.mod

@@ -0,0 +1,17 @@
+module github.com/utilitywarehouse/kube-summary-exporter
+
+go 1.15
+
+require (
+	github.com/gorilla/mux v1.8.0
+	github.com/prometheus/client_golang v1.9.0
+	k8s.io/client-go v0.20.1
+	k8s.io/kubelet v0.20.1
+)
+
+replace (
+	k8s.io/api => k8s.io/api v0.20.1
+	k8s.io/apimachinery => k8s.io/apimachinery v0.20.1
+	k8s.io/client-go => k8s.io/client-go v0.20.1
+	k8s.io/kubelet => k8s.io/kubelet v0.20.1
+)