feat: add node exporter demo (#25)

* feat: add node exporter demo

Signed-off-by: tison <[email protected]>

* fix typo

Signed-off-by: tison <[email protected]>

---------

Signed-off-by: tison <[email protected]>

node-exporter/.gitignore

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+/prometheus-data
+/prometheus.yml

node-exporter/README.md

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+# Use GreptimeDB to store and visualize data from Node Exporter
+
+## Rationales
+
+GreptimeDB implements APIs for both Prometheus remote read and remote write. You can [use GreptimeDB as a Prometheus backend](https://docs.greptime.com/user-guide/write-data/prometheus).
+
+Meanwhile, GreptimeDB [supports PromQL](https://docs.greptime.com/user-guide/query-data/promql) as its query interface, so that you can use GreptimeDB as a drop-in replacement for Prometheus.
+
+This demo showcases how to run the famous Node Exporter integrations with GreptimeDB as the storage backend.
+
+## Step 1: Set up GreptimeDB service
+
+First of all, let's get a free GreptimeDB service:
+
+1. Obtain a free GreptimeDB service from [GreptimeCloud](https://console.greptime.cloud/). 
+2. Click the "Connection Information" button and find the connection string.
+3. Export the necessary environment variables:
+
+```shell
+export GREPTIME_HOST="<host>"
+export GREPTIME_DATABASE="<dbname>"
+export GREPTIME_USERNAME="<username>"
+export GREPTIME_PASSWORD="<password>"
+```
+
+![Connection](/media/conninfo.png)
+
+## Step 2: Start the Node Exporter
+
+Node Exporter is a Prometheus exporter for hardware and OS metrics exposed by Linus or Darwin kernels.
+
+You can download and run the Node Exporter from its [release page](https://github.com/prometheus/node_exporter/releases). For example, run the following command if your system is `darwin-arm64`:
+
+```bash
+curl -fsSL -O https://github.com/prometheus/node_exporter/releases/download/v1.8.2/node_exporter-1.8.2.darwin-arm64.tar.gz
+tar -xvzf node_exporter-1.8.2.darwin-arm64.tar.gz
+cd node_exporter-1.8.2.darwin-arm64
+./node_exporter
+```
+
+The Node Exporter should print several INFO logs:
+
+```
+...
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:111 level=info msg="Enabled collectors"
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=boottime
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=cpu
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=diskstats
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=filesystem
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=loadavg
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=meminfo
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=netdev
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=os
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=powersupplyclass
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=textfile
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=thermal
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=time
+ts=2024-07-19T01:46:25.629Z caller=node_exporter.go:118 level=info collector=uname
+ts=2024-07-19T01:46:25.629Z caller=tls_config.go:313 level=info msg="Listening on" address=[::]:9100
+ts=2024-07-19T01:46:25.629Z caller=tls_config.go:316 level=info msg="TLS is disabled." http2=false address=[::]:9100
+...
+```
+
+Now, you can get the current hardware and OS metrics with:
+
+```bash
+curl http://localhost:9100/metrics
+```
+
+## Step 3: Scrape Metrics and Push to GreptimeDB
+
+As shown above, the Node Exporter only exposes an endpoint that you can query the current metrics. To scrape these metrics and push them to the GreptimeDB service, you can either:
+
+1. Start up a Prometheus instance on localhost that's configured to scrape metrics from the running Node Exporter, and remotely write to the GreptimeDB service; or,
+2. If the Node Exporter endpoint can be accessed from publish network, you can open the Web Dashboard of the GreptimeDB service, head to the Workbench tab (`https://<host>.greptime.cloud/dashboard/workbench`), and modify the `prometheus.yml` file to add the config as described below.
+
+Since the Node Exporter started above is running on localhost, this demo chooses the first option.
+
+You can download and run a Prometheus instance from its [release page](https://github.com/prometheus/prometheus/releases). For example, run the following command if your system is `darwin-arm64`:
+
+```bash
+curl -fsSL -O https://github.com/prometheus/prometheus/releases/download/v2.53.1/prometheus-2.53.1.darwin-arm64.tar.gz
+tar -xvzf prometheus-2.53.1.darwin-arm64.tar.gz
+cd prometheus-2.53.1.darwin-arm64
+```
+
+Modify the `prometheus.yml` file with:
+
+```bash
+cat <<END > prometheus.yml
+global:
+  scrape_interval: 15s
+scrape_configs:
+  - job_name: "node"
+    static_configs:
+      - targets: ["localhost:9100"]
+remote_write:
+  - url: "https://${GREPTIME_HOST}/v1/prometheus/write?db=${GREPTIME_DATABASE}"
+    basic_auth:
+      username: ${GREPTIME_USERNAME}
+      password: ${GREPTIME_PASSWORD}
+END
+```
+
+Start the bridge instance with:
+
+```bash
+./prometheus --config.file=./prometheus.yml
+```
+
+## Step 4: Visualize on GreptimeDB Dashboard
+
+You can visualize the node mertics from the Web Dashboard:
+
+![Portal](/media/portal.png)
+
+![Configure Workbench Node Exporter Full](media/workbench-dashboard.png)
+
+The "Node Exporter Full" dashboard template will give you the same charts as the Grafana Node Exporter Dashboard.
+
+![Node Exporter Full Charts](media/node-exporter-full.png)
+
+## Bonus: Visualize with Grafana Dashboard
+
+Since GreptimeDB can be used as a drop-in replacement of Prometheus, it's also possible to visualize node metrics with Grafana Dashboard with the Prometheus plugin, as if GreptimeDB is a Prometheus instance.
+
+First, start a Grafana container:
+
+```bash
+docker run -d --name=grafana -p 3000:3000 grafana/grafana
+```
+
+Open `http://localhost:3000/` at browser and log in with the default credential: both username and password are `admin`.
+
+You should add GreptimeDB as an instance of Prometheus data source. Click "Connections", "Data sources", and then "Add new data source":
+
+![Grafana Data Source](media/grafana-datasource.png)
+
+Choose "Prometheus" and add the necessary configuration:
+
+![Grafana Connection Info](media/grafana-connection-info.png)
+
+Click "Save & Test" at the button to ensure the connection is correctly set up.
+
+Then, go the "Dashboard" page and click "Create Dashboard":
+
+![Grafana Create Dashboard](media/grafana-create-dashboard.png)
+
+Choose "Import a dashboard" and then load the Node Exporter Full public template (`https://grafana.com/grafana/dashboards/1860-node-exporter-full/`):
+
+![Grafana Import Dashboard](media/grafana-import-dashboard.png)
+
+Use the data source you just registered, and click "Import". You will be redirected to the final dashboard:
+
+![Grafana Final Dashboard](media/grafana-final-dashboard.png)
+
+## Bonus: Bootstrap with a Docker Compose oneliner
+
+This demo also provides a [docker-compose.yml](docker-compose.yml) file so that you can set up the whole Node Exporter integration in one line:
+
+```bash
+docker compose up
+```
+
+Ensure the `prometheus.yml` file in the current working directory is configured as described in Step 3, and then the rest would work well.

node-exporter/docker-compose.yml

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+services:
+  node_exporter:
+    image: quay.io/prometheus/node-exporter:latest
+    container_name: node_exporter
+    command:
+      - '--path.rootfs=/host'
+    network_mode: host
+    pid: host
+    restart: unless-stopped
+    volumes:
+      - '/:/host:ro,rslave'
+
+  prometheus:
+    image: prom/prometheus:latest
+    container_name: prometheus
+    network_mode: host
+    pid: host
+    restart: unless-stopped
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml:ro
+      - ./prometheus-data:/prometheus
+    command:
+      - '--config.file=/etc/prometheus/prometheus.yml'
+      - '--storage.tsdb.path=/prometheus'
+      - '--web.enable-lifecycle'
+    depends_on:
+      - node_exporter
+    ports:
+      - '9090:9090'