pass environment variable when use `kubectl apply -f file.yaml`

Question

Can I pass environment variable when use kubectl apply -f file.yaml like kubectl apply -f file.yaml -env HOST=dev.api.host.com?

Because I have a file yaml, and I need to run in two pipelines, in one case to use host for production and in another case to use host for developlemnt.

I don't want to use two different files, I want to use one file, where I'll replace the host.

Is it possible?

Answer 1

This is how you should update environment variables in deployment yaml.

export TAG="1.11.1"
export NAME=my-nginx
envsubst < deployment.yaml | kubectl apply -f -

Answer 2

I'd recommend a different solution:

In Kubernetes you can use ConfigMaps and Secrets to store your configuration.

There are multiple ways how to do it. You could for example split development and production in 2 namespaces, if they should run in one cluster. Then you can put a ConfigMap with your host configuration in each namespace. When you deploy the same deployment to different namespaces, they'll find their appropriate ConfigMap and load it.

---

If you want to go the way of replacing it, a simple search-and-replace in your file would work.

In your file.yml specify an environment variable like this

    env:
    - name: HOST
      value: %%HOST%%

And in your pipeline replace it with the appropriate value

sed -i -e "s#%%HOST%%#http://whatever#" file.yml;