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Omar
Omar

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#054 Kubernetes - Environment Variables ConfigMaps

#kubernetes #devops #tutorial

ConfigMaps

When we have a big software we need to store environment variables in a config file which controlled by config maps.

files

original files can be found on here , I will put an copy of them inside my GitHub also because I need to edit them little bit.
so just pull the folder from my Git or clone it in case your new -> here

Lab

first let's create our deployment
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kubectl create -f app_054.yml
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then let's run it in old way not using service (because why not :p being lazy)
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kubectl get pods kubectl port-forward envtest-5864c59697-fkn4g 3000
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why 3000? will because it's specified in our app inside secretapp.js.

server.listen(3000);
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also let's take a look at our dockerfile

FROM node:9.1.0-alpine EXPOSE 3000 ENV LANGUAGE English ENV API_KEY 123-456-789 COPY secretapp.js . ENTRYPOINT node secretapp.js
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we can see that our envirements are LANGUAGE English and API_KEY 123-456-789.
But let's run our app now in browser (or curl) and type localhost:3000
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it's saying

Language: Polish API Key: 333-444-555
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because our Kubernetes will override those settings to those who are specified in our app_054.yml

apiVersion: apps/v1 kind: Deployment metadata: name: envtest spec: selector: matchLabels: name: envtest replicas: 1 template: metadata: labels: name: envtest spec: containers: - name: envtest image: praqma/secrets-demo imagePullPolicy: Always ports: - containerPort: 3000 env: - name: LANGUAGE value: Polish - name: API_KEY value: 333-444-555
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let's now move them into a config map , I call it app_054-cfmap.yml

apiVersion: v1 kind: ConfigMap metadata: name: configs data: LANGUAGE: Polish API_KEY: 333-444-555
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let's create it now
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kubectl create -f app_054-cfmap.yml kubectl get cm
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After being created let's now back to edit our main file , I will make another version in file app_054-v2.yml

apiVersion: apps/v1 kind: Deployment metadata: name: envtest spec: selector: matchLabels: name: envtest replicas: 1 template: metadata: labels: name: envtest spec: containers: - name: envtest image: praqma/secrets-demo imagePullPolicy: Always ports: - containerPort: 3000 env: - name: LANGUAGE valueFrom: configMapKeyRef: name: configs key: LANGUAGE - name: API_KEY valueFrom: configMapKeyRef: name: configs key: API_KEY
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first let's delete old deployment , and then create the newer one , and then port-forward it

kubectl delete deployment envtest kubectl create -f app_054-v2.yml kubectl port-forward envtest-7476d77786-wqntd 3000
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If we go to the browser again and type localhost:3000
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We will get same results.

Extras

now let's say I need to know what is the env variables or yml file of this config map , i type
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kubectl describe cm configs
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cm is shortcut for configmaps
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kubectl get cm configs -o yaml
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