108 lines
4.3 KiB
Markdown
108 lines
4.3 KiB
Markdown
# VPP's Interface AgentX
|
|
|
|
This is an SNMP agent that implements the [Agentx](https://datatracker.ietf.org/doc/html/rfc2257)
|
|
protocol. It connects to VPP's `statseg` (statistics memory segment) by MMAPing
|
|
it, so the user running the agent must have read access to `/run/vpp/stats.sock`.
|
|
It also connects to VPP's API endpoint, so the user running the agent must
|
|
have read/write access to `/run/vpp/api.sock`. Both of these are typically accomplished
|
|
by running the agent as group `vpp`.
|
|
|
|
The agent connects to SNMP's `agentx` socket, which can be either a TCP socket
|
|
(by default `localhost:705`), or a unix domain socket (by default `/var/agentx/master`)
|
|
the latter being readable only by root. It's preferable to run as unprivileged user,
|
|
so a TCP socket is preferred (and the default).
|
|
|
|
The agent incorporates a refactored/modified [pyagentx](https://github.com/hosthvo/pyagentx).
|
|
The upstream pyagentx code uses a threadpool and message queue, but it was not very stable.
|
|
Often, due to lack of proper locking, updaters would overwrite parts of the MIB and as a
|
|
result, any reads that were ongoing would abruptly be truncated. I refactored the code to
|
|
be single-threaded, greatly simplifying the design (and eliminating the need for locking).
|
|
|
|
To respect the original authors, this code is released with the same BSD 2-clause license.
|
|
|
|
## Building
|
|
|
|
Install `pyinstaller` to build a binary distribution
|
|
|
|
```
|
|
sudo pip install pyinstaller
|
|
pyinstaller vpp-snmp-agent.py --onefile
|
|
|
|
## Run it on console
|
|
dist/vpp-snmp-agent -h
|
|
usage: vpp-snmp-agent [-h] [-a ADDRESS] [-p PERIOD] [-d]
|
|
|
|
optional arguments:
|
|
-h, --help show this help message and exit
|
|
-a ADDRESS Location of the SNMPd agent (unix-path or host:port), default localhost:705
|
|
-p PERIOD Period to poll VPP, default 30 (seconds)
|
|
-c CONFIG Optional YAML configuration file, default empty
|
|
-d Enable debug, default False
|
|
|
|
## Install
|
|
sudo cp dist/vpp-snmp-agent /usr/sbin/
|
|
```
|
|
|
|
## Configuration file
|
|
|
|
A simple convenience configfile can provide a mapping between VPP interface names, Linux Control Plane
|
|
interface names, and descriptions. An example:
|
|
|
|
```
|
|
interfaces:
|
|
"TenGigabitEthernet6/0/0":
|
|
description: "Infra: xsw0.chrma0:2"
|
|
lcp: "xe1-0"
|
|
"TenGigabitEthernet6/0/0.3102":
|
|
description: "Infra: QinQ to L2 Provider"
|
|
lcp: "xe1-0.3102"
|
|
"TenGigabitEthernet6/0/0.310211":
|
|
description: "Cust: Customer IP Transit"
|
|
lcp: "xe1-0.3102.11"
|
|
```
|
|
|
|
This configuration file is completely optional. If the `-c` flag is empty, or it's set but the file does
|
|
not exist, the Agent will simply enumerate all interfaces, and set the `ifAlias` OID to the same value as
|
|
the `ifName`. However, if the config file is read, it will change the behavior as follows:
|
|
|
|
* Any `tapNN` interface names from VPP will be matched to their PHY by looking up their Linux Control Plane
|
|
interface. The `ifName` field will be rewritten to the _LIP_ `host-if`. For example, `tap3` above will
|
|
become `xe1-0` while `tap3.310211` will become `xe1-0.3102.11`.
|
|
* The `ifAlias` OID for a PHY will be set to the `description` field.
|
|
* The `ifAlias` OID for a TAP will be set to the string `LCP: ` followed by its PHY `ifName`. For example,
|
|
`xe1-0.3102.11` will become `LCP TenGigabitEthernet6/0/0.310211 (tap9)`
|
|
|
|
## SNMPd config
|
|
|
|
First, configure the snmpd to accept agentx connections by adding (at least) the following
|
|
to `snmpd.conf`:
|
|
```
|
|
master agentx
|
|
agentXSocket tcp:localhost:705,unix:/var/agentx-dataplane/master
|
|
```
|
|
|
|
and restart snmpd to pick up the changes. Simply run `./vpp-snmp-agent.py` and it
|
|
will connect to the snmpd on localhost:705, and expose the IFMib by periodically
|
|
polling VPP. Observe the console output.
|
|
|
|
|
|
## Running in production
|
|
|
|
Meant to be run on Ubuntu, copy `*.service`, disable the main snmpd, enable
|
|
the one that runs in the dataplane network namespace and start it all up:
|
|
|
|
```
|
|
sudo cp netns-dataplane.service /usr/lib/systemd/system/
|
|
sudo cp snmpd-dataplane.service /usr/lib/systemd/system/
|
|
sudo cp vpp-snmp-agent.service /usr/lib/systemd/system/
|
|
sudo systemctl daemon-reload
|
|
sudo systemctl stop snmpd
|
|
sudo systemctl disable snmpd
|
|
sudo systemctl enable netns-dataplane
|
|
sudo systemctl start netns-dataplane
|
|
sudo systemctl enable snmpd-dataplane
|
|
sudo systemctl start snmpd-dataplane
|
|
sudo systemctl enable vpp-snmp-agent
|
|
sudo systemctl start vpp-snmp-agent
|
|
```
|