K8s Service does not seem to be accessible on UDP port when Instana is configured with Statsd enabled

[talitz]

Hi guys,

Issue Description: I installed Instana's agent in my k8s cluster with the operator (EKS, v1.23.17-eks-2d98532).
The CRD for InstanaAgent is as follows:

apiVersion: instana.io/v1
kind: InstanaAgent
metadata:
  name: instana-agent
  namespace: instana-agent
spec:
  zone:
    name: solutions
  cluster:
      name: solutions
  agent:
    key: <MY_KEY>
    endpointHost: ingress-green-saas.instana.io
    endpointPort: "443"
    env: {}
    configuration_yaml: |
      com.instana.plugin.statsd:
        enabled: true
        ports:
          udp: 8125
          mgmt: 8126
        bind-ip: "0.0.0.0" # all IPs by default
        flush-interval: 10 # in seconds

With this setup, a service is created by the operator that expose the instana-agent pods:

apiVersion: v1
kind: Service
metadata:
  annotations:
    meta.helm.sh/release-name: instana-agent
    meta.helm.sh/release-namespace: instana-agent
  creationTimestamp: "2023-10-02T12:05:59Z"
  labels:
    app.kubernetes.io/instance: instana-agent
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: instana-agent
    app.kubernetes.io/version: 1.2.63
    helm.sh/chart: instana-agent-1.2.63
  name: instana-agent
  namespace: instana-agent
  ownerReferences:
  - apiVersion: instana.io/v1
    blockOwnerDeletion: true
    controller: true
    kind: InstanaAgent
    name: instana-agent
    uid: 318e7d05-e800-4f1b-8722-3ef830bb4372
  resourceVersion: "178751591"
  uid: 582f9998-6236-4d1c-b855-1eb8907c379b
spec:
  clusterIP: 172.20.98.212
  clusterIPs:
  - 172.20.98.212
  internalTrafficPolicy: Local
  ipFamilies:
  - IPv4
  ipFamilyPolicy: SingleStack
  ports:
  - name: agent-apis
    port: 42699
    protocol: TCP
    targetPort: 42699
  - name: opentelemetry
    port: 55680
    protocol: TCP
    targetPort: 55680
  - name: opentelemetry-iana
    port: 4317
    protocol: TCP
    targetPort: 4317
  - name: opentelemetry-http
    port: 4318
    protocol: TCP
    targetPort: 4318
  selector:
    app.kubernetes.io/instance: instana-agent
    app.kubernetes.io/name: instana-agent
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

But for some reason i'm not able to send any metric via this service to instana:

echo "TestForLightrun:3|c" | nc -u -w1 instana-agent.instana-agent.svc.cluster.local 8125
After looking at the service it doesn't even seem to expose the pods under the UDP port 8125. Is it a bug? Did I miss some configuration?

Workaround: Communicating directly with the IPs that are allocated to the pod, in that case it works and metrics are being sent to Instana through Statsd:

echo "YourMetricValue:3|c" | nc -u -w1 10.50.21.132 8125

Another question - what if I need to send UDP requests from a cluster outside of where the instana-agent is installed? Do I have a way to deploy an ingress object or I have to do it separately on my own?

[zynpsnltrkk]

having the same issue in my rosa cluster ( OpenShift:4.12.45 ) while sending the custom metrics from my application to Instana Agent Operator (2.0.17)

# nc -u -w1 instana-agent.instana-agent.svc.cluster.local 8125 -vvv
Connection to instana-agent.instana-agent.svc.cluster.local 8125 port [udp/*] succeeded!

It seems the connection established but there are no logs in the Instana pods and no custom metrics appears in the ui

[zach-robinson]

Will look into this. For now, at least, I would recommend using the Downward API in Kubernetes to acquire the agent's IP within your workload pods.