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Question

How can you read a database port from application.properties with environment variables

11/17/2019

i am very new to Spring Boot and the application.properties. I have the problem, that i need to be very flexible with my database port, because i have two different databases. Therefore i want to read the port from a environment variable. I tried the following:

spring.data.mongodb.uri = mongodb://project1:${db-password}@abc:12345/project

This code works fine, if my Database has the port 12345. But if i now try to read the port from an environment variable there is a problem. I tried this:

spring.data.mongodb.uri = mongodb://project1:${db-password}@abc:${port}/project

The problem is the following: I am using k8 and Jenkins. The environment variable "port" is given to my program in my k8 and this works fine for "db-password", but not for the port. My Jenkins says: "The connection string contains an invalid host 'abd:${port}'. The port '${port}' is not a valid, it must be an integer between 0 and 65535"

So now to my question: How can i read a port as an environment variable, without getting this error?

Thank you in advance!

-- slaayaah

environment

environment-variables

jenkins

kubernetes

port

1 Answer

11/28/2019

To inject environment variable to the pods you can do the following:

Configmap

You can create ConfigMap and configure your pods to use it.

Steps required:

Create ConfigMap
Update/Create the deployment with ConfigMap
Test it

Create ConfigMap

I provided simple ConfigMap below to store your variables:

apiVersion: v1
kind: ConfigMap
metadata:
  name: example-config
data:
  port: "12345"

To apply it and be able to use it invoke following command:

$ kubectl create -f example-configmap.yaml

The ConfigMap above will create the environment variable port with value of 12345.

Check if ConfigMap was created successfully:

$ kubectl get configmap

Output should be like this:

NAME             DATA   AGE
example-config   1      21m

To get the detailed information you can check it with command:

$ kubectl describe configmap example-config

With output:

Name:         example-config
Namespace:    default
Labels:       <none>
Annotations:  <none>
Data
====
port:
----
12345
Events:  <none>

Update/Create the deployment with ConfigMap

I provided simple deployment with ConfigMap included:

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        envFrom:
          - configMapRef:
              name: example-config
        ports:
        - containerPort: 80

Configuration responsible for using ConfigMap:

        envFrom:
          - configMapRef:
              name: example-config

After that you need to run your deployment with command:

$ kubectl create -f configmap-test.yaml

And check if it's working:

$ kubectl get pods

With output:

NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-84d6f58895-b4zvz   1/1     Running   0          23m
nginx-deployment-84d6f58895-dp4c7   1/1     Running   0          23m

Test it

To test if environment variable is working you need to get inside the pod and check for yourself.

To do that invoke the command:

$ kubectl exec -it NAME_OF_POD -- /bin/bash

Please provide the variable NAME_OF_POD with appropriate one for your case.

After successfully getting into container run:

$ echo $port

It should show:

root@nginx-deployment-84d6f58895-b4zvz:/# echo $port
12345

Now you can use your environment variables inside pods.

-- Dawid Kruk

Source: StackOverflow

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