如何在 kubectl 部署中传递环境变量？

Question

I am setting up the kubernetes setup for django webapp.

I am passing environment variable while creating deployment as below

kubectl create -f deployment.yml -l key1=value1 

I am getting error as below

error: no objects passed to create

Able to create the deployment successfully, If i remove the env variable -l key1=value1 while creating deployment.

deployment.yaml as below

#Deployment
apiVersion: extensions/v1beta1
kind: Deployment
metadata: 
 labels: 
   service: sigma-service
 name: $key1

What will be the reason for causing the above error while creating deployment?

Answer 1

I used envsubst ( https://www.gnu.org/software/gettext/manual/html_node/envsubst-Invocation.html ) for this. Create a deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: $NAME
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

Then:

export NAME=my-test-nginx
envsubst < deployment.yaml | kubectl apply -f -

Not sure what OS are you using to run this. On macOS, envsubst installed like:

brew install gettext
brew link --force gettext 

Answer 2

This isn't a right way to use the deployment, you can't provide half details in yaml and half in kubectl commands. If you want to pass environment variables in your deployment you should add those detail in the deployment spec.template.spec :

You should add following block to your deployment.yaml

spec:
  containers:
  - env:
    - name: var1
      value: val1

This will export your environment variables inside the container.

The other way to export the environment variable is use kubectl run (not advisable) as it is going to be depreciated very soon. You can use following command:

 kubectl run nginx --image=nginx --restart=Always --replicas=1 --env=var1=val1

The above command will create a deployment nginx with replica 1 and environment variable var1=val1

Answer 3

You cannot pass variables to "kubectl create -f". YAML files should be complete manifests without variables. Also you cannot use "-l" flag to "kubectl create -f".

If you want to pass environment variables to pod you should do like that:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        env:
        - name: MY_VAT
          value: MY_VALUE
        ports:
        - containerPort: 80

Read more here: https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/

Answer 4

Follow the below steps

create test-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: MYAPP
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

using sed command you can update the deployment name at deployment time

sed -e 's|MYAPP|my-nginx|g' test-deploy.yaml | kubectl apply -f -

Answer 5

File: ./deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: MYAPP
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
      ports:
      - containerPort: 80

File: ./service.yaml

apiVersion: v1
kind: Service
metadata:
  name: MYAPP
  labels:
    app: nginx
spec:
  type: ClusterIP
  ports:
  - port: 80
  selector:
    app: nginx

File: ./kustomization.yaml

resources:
- deployment.yaml
- service.yaml

If you're using https://kustomize.io/ , you can do this trick in a CI:

sh '( echo "images:" ; echo "  - name: $IMAGE" ; echo "    newTag: $VERSION" ) >> ./kustomization.yaml'
sh "kubectl apply --kustomize ."

Answer 6

I chose yq since it is yaml aware and gives a precise control where text substitutions happen.

To set an image from bash env var:

export IMAGE="your_image:latest"
yq eval '.spec.template.spec.containers[0].image = "'$IMAGE'"' manifests/daemonset.yaml | kubectl apply -f -

yq is available on MacPorts (as of 19/04/21 v4.4.1) with sudo port install yq

Answer 7

I was facing the same problem. I created a python script to change simple/complex or add values to the YAML file. This became very handy in a similar situation that you describe. Also, switching to the python domain can allow for more complex scenarios.

The code and how to use it are available at this gist. https://gist.github.com/washraf/f81153270c80b0b4ecf90a53872abde7

Answer 8

Please try following

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: kdpd00201
  name: frontend
  labels:
    app: nginx
spec:
  replicas: 6
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: frontend
        image: ifccncf/nginx:1.14.2
        ports:
        - containerPort: 8001
        env:
           - name: NGINX_PORT
             value: "8001"

Answer 9

My solution is then

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: frontend
  name: frontend
  namespace: kdpd00201
spec:
  replicas: 4
  selector:
    matchLabels:
      app: frontend
  strategy: {}
  template:
    metadata:
      creationTimestamp: null      
      labels:
        app: frontend
    spec:
      containers:
      - env: # modified level
        - name: NGINX_PORT
          value: "8080"
        image: lfccncf/nginx:1.13.7
        name: nginx
        ports:  
          - containerPort: 8080