connect flask app to Prometheus in Kubernetes cluster - kubernetes

Question

I'm new with Prometheus and I have simple flask app in Kubernetes cluster also I have Prometheus-Monitoring-Grafana services in cluster too in namespace calles prometheus-monitoring. But the problem is when I create ServiceMonitor via .yaml file to connect my app to monitor with Prometheus I see that targets is not added but in config i see that job was added. But status in Prometheus - Service Discovery is Dropped.
A have no idea why my service is not connect to serviceMonitor
serviceMonitor/default/monitoring-webapp/0 (0 / 2 active targets)
app.py
app = Flask(__name__)
metrics = PrometheusMetrics(app)
#app.route('/api')
def index():
return 'ok'
deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: webapp-deployment
labels:
app: webapp
spec:
replicas: 1
selector:
matchLabels:
app: webapp
template:
metadata:
labels:
app: webapp
spec:
containers:
- name: webapp
image: dmitriy83/flask_one:latest
imagePullPolicy: Always
resources:
requests:
memory: "64Mi"
cpu: "250m"
limits:
memory: "128Mi"
cpu: "500m"
ports:
- containerPort: 5000
env:
- name: flask_url
value: http://flasktwo-service:5003
imagePullSecrets:
- name: dockersecret
---
apiVersion: v1
kind: Service
metadata:
name: webapp-service
spec:
selector:
app: webapp
ports:
- name: service
protocol: TCP
port: 5000
targetPort: 5000
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
name: monitoring-webapp
labels:
release: prometheus-monitoring
app: webapp
spec:
endpoints:
- path: /metrics
port: service
targetPort: 5000
namespaceSelector:
matchNames:
- default
selector:
matchLabels:
app: webapp

Answer 1

Finally i figured it out. The issue was port name. Please find workable solution below
deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: webapp
labels:
component: backend
instance: app
name: containers-my-app
namespace: default
spec:
selector:
matchLabels:
component: backend
instance: app
name: containers-my-app
template:
metadata:
labels:
component: backend
instance: app
name: containers-my-app
spec:
containers:
- name: app
image: dmitriy83/flask_one:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 5000
name: webapp
imagePullSecrets:
- name: myregistrykey
service.yaml
apiVersion: v1
kind: Service
metadata:
name: webapp
labels:
component: backend
instance: app
name: containers-my-app
namespace: default
spec:
type: ClusterIP
ports:
- name: http
port: 5000
protocol: TCP
targetPort: webapp # one of the major thing w/o it you could not have active targets in Prometheus
selector:
component: backend
instance: app
name: containers-my-app
finally monitor.yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
name: webapp-super
labels:
component: backend
instance: app
name: containers-my-app
release: kube-prometheus-stack # You need to verify what is your realease name pf prometheus
namespace: prometheus-monitoring # choose in what name space your prometheus is
spec:
namespaceSelector:
matchNames:
- default
selector:
matchLabels:
component: backend
instance: app
name: containers-my-app
endpoints:
- port: http # http - is a port name which was put in service.yaml