Architecture

The overall system architecture is depicted on the following high-level diagram:

_images/arch.png

Technically, the system consists of a handful of daemons and WSGI applications. Let’s examine the roles of the main ones:

REST API server

The snmpsim-mgmt-restapi tool is a WSGI application implementing Management API server. Also known as snmpsim_control_plane.wsgi.management:app when run under a WSGI server.

In response to management operations, snmpsim-mgmt-restapi tool will generate (or remove) one or more executable scripts designed to invoke SNMP Simulator Command Responder instances.

For example, for a simple configuration such script would looks like this:

$ cat /tmp/snmpsim-run-labs.sh
#!/bin/bash
#
# SNMP Simulator Command Responder invocation script
# Automatically generated from REST API DB data - do not edit!
#
exec snmpsim-command-responder \
    --v3-engine-id "auto" \
      --v3-user "simulator" \
      --agent-udpv4-endpoint "127.0.0.1:1161" \
      --data-dir "data"

Process supervisor

One or more SNMP Simulator Command Responder instances are invoked, kept running and eventually killed by snmpsim-mgmt-supervisor tool.

The supervisor tool is driven by the executable scripts dis/appearing in a dedicated directory due to snmpsim-mgmt-restapi tool operations. Disappearance of the executable in the watched directory will lead to corresponding snmpsim-command-responder process termination.

Metrics REST API server

The snmpsim-metrics-restapi tool is another WSGI application implementing Metrics API server. Also known as snmpsim_control_plane.wsgi.metrics:app when run under a WSGI server.

This tool is responsible for querying its underlying SQL DB to fulfill REST API queries for metrics.

Metrics importer

The job of snmpsim-metrics-importer tool is to collect metrics files, being generated by snmpsim-command-responder and snmpsim-mgmt-supervisor tools. and upload them into the SQL DB for snmpsim-metrics-restapi tool to consume.

Ultimately, snmpsim-metrics-restapi server exposes metrics in SQL DB to REST API clients.