How can I set JNDI configuration in a Docker overrides.yaml file? - docker

Question

If I have a java configuration bean, saying:
package com.mycompany.app.configuration;
// whatever imports
public class MyConfiguration {
private String someConfigurationValue = "defaultValue";
// getters and setters etc
}
If I set that using jetty for local testing I can do so using a config.xml file in the following form:
<myConfiguration class="com.mycompany.app.configuration.MyConfiguration" context="SomeContextAttribute">
<someConfigurationValue>http://localhost:8080</someConfigurationValue>
</myConfiguration>
However in the deployed environment in which I need to test, I will need to use docker to set these configuration values, we use jboss.
Is there a way to directly set these JNDI values? I've been looking for examples for quite a while but cannot find any. This would be in the context of a yaml file which is used to configure a k8 cluster. Apologies for the psuedocode, I would post the real code but it's all proprietary so I can't.
What I have so far for the overrides.yaml snippet is of the form:
env:
'MyConfig.SomeContextAttribute':
class_name: 'com.mycompany.app.configuration.MyConfiguration'
someConfigurationValue: 'http://localhost:8080'
However this is a complete guess.

Answer 1

You can achieve it by using ConfigMap.
A ConfigMap is an API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume.
First what you need to create ConfigMap from your file using command as below:
kubectl create configmap <map-name> <data-source>
Where <map-name> is the name you want to assign to the ConfigMap and <data-source> is the directory, file, or literal value to draw the data from. You can read more about it here.
Here is an example:
Download the sample file:
wget https://kubernetes.io/examples/configmap/game.properties
You can check what is inside this file using cat command:
cat game.properties
You will see that there are some variables in this file:
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30r
Create the ConfigMap from this file:
kubectl create configmap game-config --from-file=game.properties
You should see output that ConfigMap has been created:
configmap/game-config created
You can display details of the ConfigMap using command below:
kubectl describe configmaps game-config
You will see output as below:
Name: game-config
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
game.properties:
----
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
You can also see how yaml of this ConfigMap will look using:
kubectl get configmaps game-config -o yaml
The output will be similar:
apiVersion: v1
data:
game.properties: |-
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
kind: ConfigMap
metadata:
creationTimestamp: "2022-01-28T12:33:33Z"
name: game-config
namespace: default
resourceVersion: "2692045"
uid: 5eed4d9d-0d38-42af-bde2-5c7079a48518
Next goal is connecting ConfigMap to Pod. It could be added in yaml file of Podconfiguration.
As you can see under containersthere is envFrom section. As name is a name of ConfigMapwhich I created in previous step. You can read about envFrom here
apiVersion: v1
kind: Pod
metadata:
name: test-pod
spec:
containers:
- name: test-container
image: nginx
envFrom:
- configMapRef:
name: game-config
Create a Pod from yaml file using:
kubectl apply -f <name-of-your-file>.yaml
Final step is checking environment variables in this Pod using below command:
kubectl exec -it test-pod -- env
As you can see below, there are environment variables from simple file which I downloaded in the first step:
game.properties=enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30

Answer 2

The way to do this is as follows:
If you are attempting to set a value that looks like this in terms of fully qualified name:
com.mycompany.app.configuration.MyConfiguration#someConfigurationValue
Then that will look like the following in a yaml file:
com_mycompany_app_configuration_MyConfiguration_someConfigurationValue: 'blahValue'
It really is that simple. It does need to be set as an environment variable in the yaml, but I'm not sure whether it needs to be under env: or if that's specific to us.
I don't think there's a way of setting something in YAML that in XML would be an attribute, however. I've tried figuring that part out, but I haven't been able to.