给我一个blackbox_exporter的监控示例

blackbox_exporter 是一个 Prometheus 监控工具，专门用于对黑盒系统进行监控。以下是一个使用 blackbox_exporter 监控 HTTP 服务的示例：

1. 安装 blackbox_exporter：

$ wget https://github.com/prometheus/blackbox_exporter/releases/download/v0.18.0/blackbox_exporter-0.18.0.linux-amd64.tar.gz
$ tar xvfz blackbox_exporter-0.18.0.linux-amd64.tar.gz
$ cd blackbox_exporter-0.18.0.linux-amd64
$ sudo mv blackbox_exporter /usr/local/bin/

2. 配置 blackbox_exporter：

创建一个配置文件，例如 `blackbox.yml`：

modules:
  http_2xx:
    prober: http
    timeout: 5s
    http:
      valid_http_versions: ["HTTP/1.1", "HTTP/2"]
      method: GET
      no_follow_redirects: false
      fail_if_ssl: false

scrape_configs:
  - job_name: http
    metrics_path: /probe
    params:
      module: [http_2xx]
    static_configs:
      - targets:
        - http://www.example.com
        - https://www.example.com
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: localhost:9115

3. 启动 blackbox_exporter：

$ blackbox_exporter --config.file=blackbox.yml

4. 配置 Prometheus：

在 Prometheus 的配置文件中添加如下内容：

scrape_configs:
  - job_name: blackbox
    metrics_path: /probe
    params:
      module: [http_2xx]
    static_configs:
      - targets:
        - http://localhost:9115
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_module]
        target_label: __metrics_path__
        replacement: /probe

这样，Prometheus 就可以定期从 blackbox_exporter 获取监控