kubernetes: How to create and use configmap from multiple files - kubernetes

Question

I have the documentation regarding the configmap:
https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#define-container-environment-variables-using-configmap-data
From what I understand is I can create a config map(game-config-2) from two files
(game.properties and ui.properties) using
kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/kubectl/game.properties --from-file=configure-pod-container/configmap/kubectl/ui.properties
Now I see the configmap
kubectl describe configmaps game-config-2
Name: game-config-2
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
game.properties: 158 bytes
ui.properties: 83 bytes
How can I use that configmap? I tried this way:
envFrom:
- configMapRef:
name: game-config-2
But this is not working, the env variable is not picking from the configmap. Or can I have two configMapRef under envFrom?

Answer 1

Yes, a pod or deployment can get env From a bunch of configMapRef entries:
spec:
containers:
- name: encouragement-api
image: registry-......../....../encouragement.api
ports:
- containerPort: 80
envFrom:
- configMapRef:
name: general-config
- configMapRef:
name: private-config
Best to create them from yaml files for k8s law and order:
config_general.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: general-config
data:
HOSTNAME: Develop_hostname
COMPUTERNAME: Develop_compname
ASPNETCORE_ENVIRONMENT: Development
encouragement-api/config_private.yaml:
apiVersion: v1
kind: ConfigMap
metadata:
name: private-config
data:
PRIVATE_STUFF: real_private
apply the two configmaps:
kubectl apply -f config_general.yaml
kubectl apply -f encouragement-api/config_private.yaml
Run and exec into the pod and run env |grep PRIVATE && env |grep HOSTNAME
I have config_general.yaml laying around in the same repo as the developers' code, they can change it however they like. Passwords and sensitive values are kept in the config_private.yaml file which is sitting elsewhere (a S3 encrypted bucket) and the values there are base64 encoded for an extra bit of security.

Answer 2

One solution to this problem is to create a ConfigMap with a multiple data key/values:
apiVersion: v1
kind: ConfigMap
metadata:
name: conf
data:
game.properties: |
<paste file content here>
ui.properties: |
<paste file content here>
Just don't forget | symbol before pasting content of files.

Answer 3

Multiple --from-env-file are not allowed.
Multiple --from-file will work for you.
Eg:
cat config1.txt
var1=val1
cat config2.txt
var3=val3
var4=val4
kubectl create cm details2 --from-env-file=config1.txt --from-env-file=config2.txt -o yaml --dry-run
Output
apiVersion: v1
data:
var3: val3
var4: val4
kind: ConfigMap
name: details2
k create cm details2 --from-file=config1.txt --from-file=config2.txt -o yaml --dry-run
Output
apiVersion: v1
data:
config1.txt: |
var1=val1
config2.txt: |
var3=val3
var4=val4
kind: ConfigMap
name: details2

Answer 4

If you use Helm, it is much simpler.
Create a ConfigMap template like this
kind: ConfigMap
apiVersion: v1
metadata:
name: {{ .Values.configMapName }}
data:
{{ .Values.gameProperties.file.name }}: |
{{ tpl (.Files.Get .Values.gameProperties.file.path) }}
{{ .Values.uiProperties.file.name }}: |
{{ tpl (.Files.Get .Values.uiProperties.file.path) }}
and two files with the key:value pairs like this game.properties
GAME_NAME: NFS
and another files ui.properties
GAME_UI: NFS UI
and values.yaml should like this
configMapName: game-config-2
gameProperties:
file:
name: game.properties
path: "properties/game.properties"
uiProperties:
file:
name: ui.properties
path: "properties/ui.properties"
You can verify if templates interpolate the values from values.yaml file by helm template ., you can expect this as output
kind: ConfigMap
apiVersion: v1
metadata:
name: game-config-2
data:
game.properties: |
GAME_NAME: NFS
ui.properties: |
GAME_UI: NFS UI

Answer 5

am not sure if you can load all key:value pairs from a specific file in a configmap as environemnt variables in a pod. you can load all key:value pairs from a specific configmap as environemnt variables in a pod. see below
apiVersion: v1
kind: ConfigMap
metadata:
name: special-config
namespace: default
data:
SPECIAL_LEVEL: very
SPECIAL_TYPE: charm
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: gcr.io/google_containers/busybox
command: [ "/bin/sh", "-c", "env" ]
envFrom:
- configMapRef:
name: special-config
restartPolicy: Never
Verify that pod shows below env variables
SPECIAL_LEVEL=very
SPECIAL_TYPE=charm

Answer 6

As #Emruz_Hossain mentioned , if game.properties and ui.properties have only env variables then this can work for you
kubectl create configmap game-config-2 --from-env-file=configure-pod-container/configmap/kubectl/game.properties --from-env-file=configure-pod-container/configmap/kubectl/ui.properties