10. DPDK Telemetry API User Guide

This document describes how the Data Plane Development Kit(DPDK) Telemetry API is used for querying port statistics from incoming traffic.

10.1. Introduction

The librte_telemetry provides the functionality so that users may query metrics from incoming port traffic and global stats(application stats). The application which initializes packet forwarding will act as the server, sending metrics to the requesting application which acts as the client.

In DPDK, applications are used to initialize the telemetry. To view incoming traffic on featured ports, the application should be run first (ie. after ports are configured). Once the application is running, the service assurance agent (for example the collectd plugin) should be run to begin querying the API.

A client connects their Service Assurance application to the DPDK application via a UNIX socket. Once a connection is established, a client can send JSON messages to the DPDK application requesting metrics via another UNIX client. This request is then handled and parsed if valid. The response is then formatted in JSON and sent back to the requesting client.

10.1.1. Pre-requisites

  • Python >= 2.5
  • Jansson library for JSON serialization

10.2. Test Environment

telemetry offers a range of selftests that a client can run within the DPDK application.

Selftests are disabled by default. They can be enabled by setting the ‘selftest’ variable to 1 in rte_telemetry_initial_accept().

Note: this ‘hardcoded’ value is temporary.

10.3. Configuration

Enable the telemetry API by modifying the following config option before building DPDK:

CONFIG_RTE_LIBRTE_TELEMETRY=y

Note: Meson will pick this up automatically if libjansson is available.

10.4. Running the Application

The following steps demonstrate how to run the telemetry API to query all statistics on all active ports, using the telemetry_client python script to query. Note: This guide assumes packet generation is applicable and the user is testing with testpmd as a DPDK primary application to forward packets, although any DPDK application is applicable.

  1. Launch testpmd as the primary application with telemetry.:

    ./app/testpmd --telemetry

  2. Launch the telemetry python script with a client filepath.:

    python usertools/telemetry_client.py /var/run/some_client

    The client filepath is going to be used to setup our UNIX connection with the DPDK primary application, in this case testpmd This will initialize a menu where a client can proceed to recursively query statistics, request statistics once or unregister the file_path, thus exiting the menu.

  3. Send traffic to any or all available ports from a traffic generator. Select a query option(recursive or singular polling or global stats). The metrics will then be displayed on the client terminal in JSON format.

  4. Once finished, unregister the client using the menu command.