iLogtail

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iLogtail 是阿里云日志服务(Log Service)中的一款高性能、可扩展的日志采集工具。它被设计用于实时收集、解析和传输各类日志数据,支持多种数据源和复杂的日志处理场景,广泛应用于分布式系统、Web 服务器、应用程序等环境中的日志管理。

如何开发Flusher插件


Flusher 插件与外部系统进行交互,将数据发送到外部,以下将从接口定义与案例2方面指导如何开发 Flusher 插件

Flusher 接口定义

  • Init: 插件初始化接口,对于Flusher 主要作用是创建外部资源链接
  • Description: 插件描述
  • IsReady:插件系统在调用 Flush 前会调用该接口检查当前 flusher 是否仍能够处理更多数据,如果答案为否的话,它会等待一段时间再重试。
  • Flush 接口是插件系统向 flusher 插件实例提交数据的入口,用于将数据输出到外部系统。为了映射到日志服务的概念中,我们增加了三个string 参数,它代表这个 flusher 实例所属的project/logstore/config。
  • SetUrgent: 标识iLogtail 即将退出,将系统状态传递给具体Flusher 插件,可以供Flusher 插件自动适应系统状态,比如加快输出速率等。(SetUrgent调用发生在其他类型插件的Stop之前,当前尚无有意义的实现)
  • Stop:停止Flusher 插件,比如断开与外部系统交互的链接
type Flusher interface {
// Init called for init some system resources, like socket, mutex...
Init(Context) error
// Description returns a one-sentence description on the Input.
Description() string
// IsReady checks if flusher is ready to accept more data.
// @projectName, @logstoreName, @logstoreKey: meta of the corresponding data.
// Note: If SetUrgent is called, please make some adjustment so that IsReady
// can return true to accept more data in time and config instance can be
// stopped gracefully.
IsReady(projectName string, logstoreName string, logstoreKey int64) bool
// Flush flushes data to destination, such as SLS, console, file, etc.
// It is expected to return no error at most time because IsReady will be called
// before it to make sure there is space for next data.
Flush(projectName string, logstoreName string, configName string, logGroupList []*protocol.LogGroup) error
// SetUrgent indicates the flusher that it will be destroyed soon.
// @flag indicates if main program (Logtail mostly) will exit after calling this.
//
// Note: there might be more data to flush after SetUrgent is called, and if flag
// is true, these data will be passed to flusher through IsReady/Flush before
// program exits.
//
// Recommendation: set some state flags in this method to guide the behavior
// of other methods.
SetUrgent(flag bool)
// Stop stops flusher and release resources.
// It is time for flusher to do cleaning jobs, includes:
// 1. Flush cached but not flushed data. For flushers that contain some kinds of
// aggregation or buffering, it is important to flush cached out now, otherwise
// data will lost.
// 2. Release opened resources: goroutines, file handles, connections, etc.
// 3. Maybe more, it depends.
// In a word, flusher should only have things that can be recycled by GC after this.
Stop() error
}

Flusher 开发

Flusher 的开发分为以下步骤:

  1. 创建Issue,描述开发插件功能,会有社区同学参与讨论插件开发的可行性,如果社区review 通过,请参考步骤2继续进行。
  2. 实现 Flusher 接口,这里我们使用样例模式进行介绍,详细样例请查看flusher/stdout
  3. 通过init将插件注册到Flushers,Flusher插件的注册名(即json配置中的plugin_type)必须以”flusher_“开头,详细样例请查看flusher/stdout
    ,你可以使用 example.json 试验此插件功能。
  4. 将插件加入插件引用配置文件common配置节, 如果仅运行于指定系统,请添加到linuxwindows配置节.
  5. 进行单测或者E2E测试,请参考如何使用单测如何使用E2E测试.
  6. 使用 make lint 检查代码规范。
  7. 提交Pull Request。

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