Connect to Postgresql from inside kubernetes cluster

Question

I setup a series of VM 192.168.2.(100,105,101,104) where kubernetes master is on 100 and two workers on 101,104. Also setup the postgres on 192.168.2.105, followed this tutorial but it is still unreachable from within. Tried it in minikube inside a test VM where minikube and postgres were installed in the same VM, worked just fine.

Changed the postgers config file from localhost to *, changed listen at pg_hba.conf to 0.0.0.0/0

Installed postgesql-12 and postgresql-client-12 in the VM 192.168.2.105:5432, now i added headless service to kubernetes which is as follows

apiVersion: v1
kind: Service
metadata:
    name: my-service
spec:
    ports:
        - protocol: TCP
          port: 5432
          targetPort: 5432
------
apiVersion: v1
kind: Endpoints
metadata:
    name: my-service
subsets:
    - addresses:
        - ip: 192.168.2.105
      ports:
        - port: 5432

in my deployment I am defining this to access database

apiVersion: v1
kind: Service
metadata:
  name: keycloak
  labels:
    app: keycloak
spec:
  ports:
  - name: http
    port: 8080
    targetPort: 8080
  selector:
    app: keycloak
  type: LoadBalancer
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: keycloak
  namespace: default
  labels:
    app: keycloak
spec:
  replicas: 1
  selector:
    matchLabels:
      app: keycloak
  template:
    metadata:
      labels:
        app: keycloak
    spec:
      containers:
      - name: keycloak
        image: quay.io/keycloak/keycloak:11.0.0
        env:
        - name: KEYCLOAK_USER
          value: "admin"
        - name: KEYCLOAK_PASSWORD
          value: "admin"
        - name: PROXY_ADDRESS_FORWARDING
          value: "true"
        - name: DB_ADDR
          value: 'my-service:5432'
        - name: DB_DATABASE
          value: postgres
        - name: DB_PASSWORD
          value: admin
        - name: DB_SCHEMA
          value: public
        - name: DB_USER
          value: postgres
        - name: DB_VENDOR
          value: POSTGRES
        ports:
        - name: http
          containerPort: 8080
        - name: https
          containerPort: 8443
        readinessProbe:
          httpGet:
            path: /auth/realms/master
            port: 8080

Also the VMs are bridged, not on NAT.

What i am doing wrong here ?

Please add additional information to the question. Describe postgres pod and svc. — Rohit
– Rohit, Commented Aug 26, 2020 at 6:46
updated with more details about the pod, deployment and service — Mainak Das
– Mainak Das, Commented Aug 26, 2020 at 15:42
Yes, the actual problem was the headless selector is projecting to the nodeportIP:nodeport , so ive to change the environment variable in the keycloak itself ` - name: DB_ADDR value: < NodePortIP/LoadBalancer >:< NodePort > ` — Mainak Das
– Mainak Das, Commented Sep 4, 2020 at 15:13
Can you paste your solution as an answer - to stick to StackOverflow rules ? — Malgorzata
– Malgorzata, Commented Sep 9, 2020 at 10:12

Dharman · Accepted Answer · 2020-09-09 14:49:37Z

The first thing we have to do is create the headless service with custom endpoint. The IP in my solution is only specific for my machine.

Endpoint with service:

apiVersion: v1
kind: Service
metadata:
  name: postgres-service
spec:
  ports:
    - protocol: TCP
      port: 5432
      targetPort: 5432
---
apiVersion: v1
kind: Endpoints
metadata:
  name: postgres-service
subsets:
  - addresses:
      - ip: 192.168.2.105
    ports:
      - port: 5432

As for my particular specs, I haven't defined any ingress or loadbalancer so i'll change the selector type from LoadBalancer to NodePort in the service after its deployed.

Now i deployed the keycloak with the the mentioned .yaml file

apiVersion: v1
kind: Service
metadata:
  name: keycloak
  labels:
    app: keycloak
spec:
  ports:
    - name: http
      port: 8080
      targetPort: 8080
    - name: https
      port: 8443
      targetPort: 8443
  selector:
    app: keycloak
  type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: keycloak
  namespace: default
  labels:
    app: keycloak
spec:
  replicas: 1
  selector:
    matchLabels:
      app: keycloak
  template:
    metadata:
      labels:
        app: keycloak
    spec:
      containers:
        - name: keycloak
          image: quay.io/keycloak/keycloak:11.0.0
          env:
            - name: KEYCLOAK_USER
              value: "admin" # TODO give username for master realm
            - name: KEYCLOAK_PASSWORD
              value: "admin" # TODO give password for master realm
            - name: PROXY_ADDRESS_FORWARDING
              value: "true"
            - name: DB_ADDR
              value: # <Node-IP>:<LoadBalancer-Port/ NodePort>
            - name: DB_DATABASE
              value: "keycloak" # Database to use
            - name: DB_PASSWORD
              value: "admin" # Database password
            - name: DB_SCHEMA
              value: public
            - name: DB_USER
              value: "postgres" # Database user
            - name: DB_VENDOR
              value: POSTGRES
          ports:
            - name: http
              containerPort: 8080
            - name: https
              containerPort: 8443
          readinessProbe:
            httpGet:
              path: /auth/realms/master
              port: 8080

After mentioning all the possible values, it connects successfully to the postgres server that is hosted on another server away from kubernetes master and workers node !

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