K
Q

Kubernetes directory configMap and java system properties

3/18/2019

I'm trying to use a directory config map as a mounted volume inside of my docker container running a spring boot application. I am passing some of the mounted paths to the things like the spring application.yaml, but it doesn't appear the mount is working as expected as it can't find the config. For example

Create the configmap like so

kubectl create configmap example-config-dir \
 --from-file=/example/config/

Kubernetes yaml

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: example
  labels:
   app: example
spec:
  replicas: 1
  selector:
   matchLabels:
     app: example
  template:
    metadata:
      labels:
        app: example
    spec:
     containers:
     - name: example
       image: example:latest
       ports:
         - containerPort: 8443
       volumeMounts:
          - name: config-vol
            mountPath: /config
     volumes:
       - name: config-vol
         configMap:
           name: example-config-dir

And the Dockerfile (there are other steps which copy the jar file in which I haven't detailed)

VOLUME /tmp
RUN echo "java -Dspring.config.location=file:///config/ -jar myjarfile.jar" > ./start-spring-boot-app.sh"
CMD ["sh", "start-spring-boot-app.sh"]
-- PDStat
docker
kubernetes
spring-boot

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1 Answer

3/18/2019

As explained in Create ConfigMaps from Directories and Create ConfigMaps from files, when you create a ConfigMap using --from-file, the filename becomes a key stored in the data section of the ConfigMap. The file contents become the key’s value.

To do the way you want, a better way would be creating the yml like this

apiVersion: v1
kind: ConfigMap
metadata:
  name: special-config
  namespace: default
data:
  SPECIAL_LEVEL: very
  SPECIAL_TYPE: charm

and then apply like this:

kubectl create -f https://k8s.io/examples/configmap/configmap-multikeys.yaml

When the pod runs, the command ls /config produces the output below:

special.level
special.type

The way you did, should generate a file with same name as your original files and within it the contents of the file.

-- Diego Mendes
Source: StackOverflow