# 监控
Fluent Bit 带有内置的 HTTP 服务，可用于查询内部信息并监控每个正在运行的插件的指标。
监控接口可以轻松地与 Prometheus 集成，因为我们支持 Prometheus 原生格式。
## 快速开始
首先，第一步是修改配置文件以启用 HTTP Server:
```
[SERVICE]
HTTP_Server On
HTTP_Listen 0.0.0.0
HTTP_PORT 2020
[INPUT]
Name cpu
[OUTPUT]
Name stdout
Match *
```
上面的配置代码片段将指示 Fluent Bit 在 TCP/2020 端口上启动 HTTP Server 并在所有网络接口上进行监听:
```
$ bin/fluent-bit -c fluent-bit.conf
Fluent Bit v1.4.0
* Copyright (C) 2019-2020 The Fluent Bit Authors
* Copyright (C) 2015-2018 Treasure Data
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io
[2020/03/10 19:08:24] [ info] [engine] started
[2020/03/10 19:08:24] [ info] [http_server] listen iface=0.0.0.0 tcp_port=2020
```
现在使用简单 **curl** 命令就可以收集一些信息:
```
$ curl -s http://127.0.0.1:2020 | jq
{
"fluent-bit": {
"version": "0.13.0",
"edition": "Community",
"flags": [
"FLB_HAVE_TLS",
"FLB_HAVE_METRICS",
"FLB_HAVE_SQLDB",
"FLB_HAVE_TRACE",
"FLB_HAVE_HTTP_SERVER",
"FLB_HAVE_FLUSH_LIBCO",
"FLB_HAVE_SYSTEMD",
"FLB_HAVE_VALGRIND",
"FLB_HAVE_FORK",
"FLB_HAVE_PROXY_GO",
"FLB_HAVE_REGEX",
"FLB_HAVE_C_TLS",
"FLB_HAVE_SETJMP",
"FLB_HAVE_ACCEPT4",
"FLB_HAVE_INOTIFY"
]
}
}
```
请注意，我们正在将 *curl* 命令输出发送到 *jq* 程序，这有助于从终端读取 JSON 数据。Fluent Bit 并非旨在进行 JSON 优雅打印。
## REST API Interface
Fluent Bit 公开了许多有用的监控接口，从 Fluent Bit v0.14 开始，以下端点可用:
| URI | Description | Data Format |
| -------------------------- | ----------------------------- | --------------------- |
| / | Fluent Bit 构建信息 | JSON |
| /api/v1/uptime | 以秒和可读的格式获取正常运行的时间 | JSON |
| /api/v1/metrics | 已加载插件的内部指标 | JSON |
| /api/v1/metrics/prometheus | 可以被 Prometheus 服务获取已加载插件的内部指标 | Prometheus Text 0.0.4 |
## Uptime Example
使用以下命令查询服务正常运行时间:
```
$ curl -s http://127.0.0.1:2020/api/v1/uptime | jq
```
它应该打印类似如下的输出:
```javascript
{
"uptime_sec": 8950000,
"uptime_hr": "Fluent Bit has been running: 103 days, 14 hours, 6 minutes and 40 seconds"
}
```
## Metrics Examples
使用以下命令查询 JSON 格式的内部指标:
```bash
$ curl -s http://127.0.0.1:2020/api/v1/metrics | jq
```
it should print a similar output like this:
```javascript
{
"input": {
"cpu.0": {
"records": 8,
"bytes": 2536
}
},
"output": {
"stdout.0": {
"proc_records": 5,
"proc_bytes": 1585,
"errors": 0,
"retries": 0,
"retries_failed": 0
}
}
}
```
#### Metrics in Prometheus format
查询 Prometheus Text 0.0.4 格式的内部指标:
```bash
$ curl -s http://127.0.0.1:2020/api/v1/metrics/prometheus
```
这次，相同的指标将以 Prometheus 格式输出，而不是 JSON
```
fluentbit_input_records_total{name="cpu.0"} 57 1509150350542
fluentbit_input_bytes_total{name="cpu.0"} 18069 1509150350542
fluentbit_output_proc_records_total{name="stdout.0"} 54 1509150350542
fluentbit_output_proc_bytes_total{name="stdout.0"} 17118 1509150350542
fluentbit_output_errors_total{name="stdout.0"} 0 1509150350542
fluentbit_output_retries_total{name="stdout.0"} 0 1509150350542
fluentbit_output_retries_failed_total{name="stdout.0"} 0 1509150350542
```
### 配置别名
默认情况下，在运行时配置的插件会以 *`plugin_name.ID`* 的格式获取内部名称。出于监控目的，如果配置了多个相同类型的插件，可能会造成混淆。为了区别，每个配置的输入或输出部分都可以使用*别名*，它将用作指标的父名称。
下面的示例使用 [CPU](https://app.gitbook.com/s/-M7r4TRvogEqaAD3Fmce/pipline/inputs/cpu.md) 输入插件的 INPUT 部分设置别名:
```
[SERVICE]
HTTP_Server On
HTTP_Listen 0.0.0.0
HTTP_PORT 2020
[INPUT]
Name cpu
Alias server1_cpu
[OUTPUT]
Name stdout
Alias raw_output
Match *
```
当查询指标时，我们获取到了设置的别名而不是插件的名称:
```javascript
{
"input": {
"server1_cpu": {
"records": 8,
"bytes": 2536
}
},
"output": {
"raw_output": {
"proc_records": 5,
"proc_bytes": 1585,
"errors": 0,
"retries": 0,
"retries_failed": 0
}
}
}
```
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