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

Question

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!

Answer 1

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.