Exposes Prometheus metrics on port 8000 when enabled.
In particular, it exposes a Gauge, Blender_Render, that is 1 when the Blender instance is rendering, and 0 when it is not. The standard metrics, like cpu usage are also exposed.
Building the add-on
Currently we use an embedded and slightly modified version of the prometheus_client for Python, which is in the subdirectory. That is not ideal and might change once I have figured out how to monkey path the server instead of hacking the source, but i don´t like to depend on external Python packages because that makes it difficult to distribute and add-on.
Copying is also very far from ideal, so a git sub-repository is probably the way to go.
git clone https://github.com/varkenvarken/blenderaddons.git
cd blenderaddons
zip -urv prometheus.zip prometheus
Then install prometheus.zip in the usual way and enable the add-on.
You can inspect the published metrics on http://localhost:8000.
Scraping this with a Prometheus container and creating a Grafana dashboard is something you'll have to figure out yourself.
Source code
Available on Github.
The code is extremely simple: when the add-on is enabled we create a Gauge metric and start the prometheus http server. We then register a Blender timer that checks every 10 seconds if we are rendering or not with the is_app_running() function and sets the Gauge accordingly.
The timer is made persistent, so it will keep running even if we load another .blend file.
The Prometheus server is running in a separate (daemon) thread and will only end if we exit Blender or if we invoke our custom stop_http_server() function, and that's where the ugly hack comes in: the start_http-server() function does not return the server it creates, so w e have no way to call its shutdown() function (which is present, because it is a subclass of http.server) or call close() on the socket it is listening on, and this would prevent us from disabling and then enabling the add-on again, because we would get an address in use exception.
Same goes for the Gauge: If we want o be able to reenable the add-on we have to make sure to remove it from the registry in the unregister() function.
import bpy # type: ignore
from .prometheus_client import Gauge, start_http_server, stop_http_server, REGISTRY
def every_10_seconds():
global g
r = bpy.app.is_job_running("RENDER")
if r:
g.set(1.0)
else:
g.set(0.0)
return 10.0
def register():
global g
g = Gauge("Blender_Render", "Rendering processes")
start_http_server(8000)
bpy.app.timers.register(every_10_seconds, persistent=True)
def unregister():
global g
bpy.app.timers.unregister(every_10_seconds)
REGISTRY.unregister(g)
stop_http_server()
