Background: I'm going to be doing some experiments with OpenFaaS (running in Kubernetes) where I will be invoking several asynchronous execution requests. OpenFaaS uses NATS Streaming to queue these requests for asynchronous function execution.
What I need is a way to determine the size of this NATS Streaming queue so I can know how many items are in the queue. Is there a command to get the size or number of items in a NATS Streaming Queue? I searched Google and the NATS documentation and found nothing of use.
I did find the command kubectl logs deployment/queue-worker -n openfaas from here which displays the logs of the queue; however, this is not quite what I want (I want the number of items left in the queue, not the queue's full logs).
You can enable a monitoring endpoint in NATS to get a number of general endpoints to query which can go down to a specific channel.
You would then need to expose a Service for that endpoint in Kubernetes for external access, probably via an Ingress if you want more control over which endpoints and how they are exposed.
Have a look at the templates in a nats-streaming-ft helm chart.
Add the monitoring port to your container spec
spec:
containers:
- name: nats-streaming
args:
- /opt/nats-streaming-server
- --http_port=8222And the chosen monitoring port to your ports list in the Service.
apiVersion: v1
kind: Service
metadata:
name: nats-monitoring
labels:
app: nats
spec:
selector:
app: nats
ports:
- name: monitoring
protocol: TCP
port: 8222