Telegraf aggregator and processor plugins

Besides the input plugins and output plugins, Telegraf includes aggregator and processor plugins, which are used to aggregate and process metrics as they pass through Telegraf.

┌───────────┐
│           │
│    CPU    │───┐
│           │   │
└───────────┘   │
                │
┌───────────┐   │                                              ┌───────────┐
│           │   │                                              │           │
│  Memory   │───┤                                          ┌──▶│ InfluxDB  │
│           │   │                                          │   │           │
└───────────┘   │    ┌─────────────┐     ┌─────────────┐   │   └───────────┘
                │    │             │     │Aggregate    │   │
┌───────────┐   │    │Process      │     │ - mean      │   │   ┌───────────┐
│           │   │    │ - transform │     │ - quantiles │   │   │           │
│   MySQL   │───┼──▶│ - decorate  │────▶│ - min/max   │───┼──▶│   File    │
│           │   │    │ - filter    │     │ - count     │   │   │           │
└───────────┘   │    │             │     │             │   │   └───────────┘
                │    └─────────────┘     └─────────────┘   │
┌───────────┐   │                                          │   ┌───────────┐
│           │   │                                          │   │           │
│   SNMP    │───┤                                          └──▶│   Kafka   │
│           │   │                                              │           │
└───────────┘   │                                              └───────────┘
                │
┌───────────┐   │
│           │   │
│  Docker   │───┘
│           │
└───────────┘

Processor plugins process metrics as they pass through and immediately emit results based on the values they process. For example, this could be printing all metrics or adding a tag to all metrics that pass through.

Aggregator plugins, on the other hand, are a bit more complicated. Aggregators are typically for emitting new aggregate metrics, such as a running mean, minimum, maximum, quantiles, or standard deviation. For this reason, all aggregator plugins are configured with a period. The period is the size of the window of metrics that each aggregate represents. In other words, the emitted aggregate metric will be the aggregated value of the past period seconds. Since many users will only care about their aggregates and not every single metric gathered, there is also a drop_original argument, which tells Telegraf to only emit the aggregates and not the original metrics.

NOTE Since aggregator plugins only aggregate metrics within their periods, historical data is not supported. In other words, if your metric timestamp is more than now() - period in the past, it will not be aggregated. If this is a feature that you need, please comment on this GitHub issue.