# Vivo Exporter Vivo Exporter is an output plugin that exposes logs, metrics, and traces through an HTTP endpoint. This plugin aims to be used in conjunction with [Vivo project](https://github.com/calyptia/vivo) . ### Configuration Parameters | Key | Description | Default | | ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------ | ------- | | `empty_stream_on_read` | If enabled, when an HTTP client consumes the data from a stream, the stream content will be removed. | Off | | `stream_queue_size` | Specify the maximum queue size per stream. Each specific stream for logs, metrics and traces can hold up to `stream_queue_size` bytes. | 20M | | `http_cors_allow_origin` | Specify the value for the HTTP Access-Control-Allow-Origin header (CORS). | | | `workers` | The number of [workers](https://docs.fluentbit.io/manual/3.1/administration/multithreading#outputs) to perform flush operations for this output. | `1` | ### Getting Started Here is a simple configuration of Vivo Exporter, note that this example is not based on defaults. ```python [INPUT] name dummy tag events rate 2 [OUTPUT] name vivo_exporter match * empty_stream_on_read off stream_queue_size 20M http_cors_allow_origin * ``` ### How it works Vivo Exporter provides buffers that serve as streams for each telemetry data type, in this case, `logs`, `metrics`, and `traces`. Each buffer contains a fixed capacity in terms of size (20M by default). When the data arrives at a stream, it’s appended to the end. If the buffer is full, it removes the older entries to make room for new data. The `data` that arrives is a `chunk`. A chunk is a group of events that belongs to the same type (logs, metrics or traces) and contains the same `tag`. Every chunk placed in a stream is assigned with an auto-incremented `id`. #### Requesting data from the streams By using a simple HTTP request, you can retrieve the data from the streams. The following are the endpoints available: | endpoint | Description | | ---------- | ----------------------------------------------------------------------------------------------------------------------------- | | `/logs` | Exposes log events in JSON format. Each event contains a timestamp, metadata and the event content. | | `/metrics` | Exposes metrics events in JSON format. Each metric contains name, metadata, metric type and labels (dimensions). | | `/traces` | Exposes traces events in JSON format. Each trace contains a name, resource spans, spans, attributes, events information, etc. | The example below will generate dummy log events which will be consuming by using `curl` HTTP command line client: **Configure and start Fluent Bit** ```python [INPUT] name dummy tag events rate 2 [OUTPUT] name vivo_exporter match * ``` **Retrieve the data** ```bash curl -i http://127.0.0.1:2025/logs ``` > We are using the `-i` curl option to print also the HTTP response headers. Curl output would look like this: ```bash HTTP/1.1 200 OK Server: Monkey/1.7.0 Date: Tue, 21 Mar 2023 16:42:28 GMT Transfer-Encoding: chunked Content-Type: application/json Vivo-Stream-Start-ID: 0 Vivo-Stream-End-ID: 3 [[1679416945459254000,{"_tag":"events"}],{"message":"dummy"}] [[1679416945959398000,{"_tag":"events"}],{"message":"dummy"}] [[1679416946459271000,{"_tag":"events"}],{"message":"dummy"}] [[1679416946959943000,{"_tag":"events"}],{"message":"dummy"}] [[1679416947459806000,{"_tag":"events"}],{"message":"dummy"}] [[1679416947958777000,{"_tag":"events"}],{"message":"dummy"}] [[1679416948459391000,{"_tag":"events"}],{"message":"dummy"}] ``` ### Streams and IDs As mentioned above, on each stream we buffer a `chunk` that contains N events, each chunk contains it own ID which is unique inside the stream. When we receive the HTTP response, Vivo Exporter also reports the range of chunk IDs that were served in the response via the HTTP headers `Vivo-Stream-Start-ID` and `Vivo-Stream-End-ID`. The values of these headers can be used by the client application to specify a range between IDs or set limits for the number of chunks to retrieve from the stream. ### Retrieve ranges and use limits A client might be interested into always retrieve the latest chunks available and skip previous one that already processed. In a first request without any given range, Vivo Exporter will provide all the content that exists in the buffer for the specific stream, on that response the client might want to keep the last ID (Vivo-Stream-End-ID) that was received. To query ranges or starting from specific chunks IDs, remember that they are incremental, you can use a mix of the following options: | Query string option | Description | | ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | `from` | Specify the first chunk ID that is desired to be retrieved. Note that if the `chunk` ID does not exists the next one in the queue will be provided. | | `to` | The last chunk ID is desired. If not found, the whole stream will be provided (starting from `from` if was set). | | `limit` | Limit the output to a specific number of chunks. The default value is `0`, which means: send everything. | The following example specifies the range from chunk ID 1 to chunk ID 3 and only 1 chunk: `curl -i "http://127.0.0.1:2025/logs?from=1&to=3&limit=1"` Output: ```bash HTTP/1.1 200 OK Server: Monkey/1.7.0 Date: Tue, 21 Mar 2023 16:45:05 GMT Transfer-Encoding: chunked Content-Type: application/json Vivo-Stream-Start-ID: 1 Vivo-Stream-End-ID: 1 [[1679416945959398000,{"_tag":"events"}],{"message":"dummy"}] [[1679416946459271000,{"_tag":"events"}],{"message":"dummy"}] ```