kubectl run is deprecated - looking for alternative

Solution 1:

As the author of the problem let me explain a little bit the intention behind this deprecation. Just like Brendan explains in his answer, kubectl run per se is not being deprecated, only all the generators, except for the one that creates a Pod for you.

The reason for this change is two folds:

The vast majority of input parameters for kubectl run command is overwhelming for newcomers, as well as for the old timers. It's not that easy to figure out what will be the result of your invocation. You need to take into consideration several passed options as well as the server version.
The code behind it is also a mess to maintain given the matrix of possibilities is growing faster than we can handle.

That's why we're trying to move people away from using kubectl run for their daily workflows and convince them that using explicit kubectl create commands is more straightforward. Finally, we want to make the newcomers that played with docker or any other container engine, where they run a container, to have the same experience with Kubernetes where kubectl run will just run a Pod in a cluster.

Sorry for the initial confusion and I hope this will clear things up.

UPDATE (2020/01/10): As of https://github.com/kubernetes/kubernetes/pull/87077 kubectl run will ONLY create Pods. All generators will be removed entirely.

Solution 2:

you can use:

kubectl run --generator=run-pod/v1 --image=busybox busybox --dry-run --env=foo=bar

Which isn't being deprecated.

Solution 3:

kubectl run by default, will create a Deployment.

The command in its full extend is:

kubectl run --generator=deployment/apps.v1 <deployment_name> --image=<image_to_use_in_the_container_of_the_deployment's_pod>

So the kubernetes resource that will be created upon execution of the run command is defined by the value of the --generator flag.

What the deprecation message hints (and is also clarified by the answer provided by @soltysh) is that the particular practice will be removed.

So in future kubernetes versions, the run command will by default (and as only option) create pods (and not deployments), i.e. the command in its full extend will become:

kubectl run --generator=run-pod/v1 <pod_name> --image=<image_of_the_container_of_the_pod>

In case you want to create any other kubernetes resource type, this will be impossible via run command so you will have to resort to explicit imperative create or declarative apply -f, the later pointing to kubernetes yml files with the corresponding resource defintition, as in

kubernetes apply -f <yaml_file_with_my_deployment.yml>

Solution 4:

I noticed that running the following command WITHOUT specifying the generator parameter:

kubectl run <name> --image=<image>

It returns this error:

kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.

What's very confusing about this message is that you never specified the --generator parameter in the first place. However the main point here is to explicitly specify the generator as directed by the error message as follows:

kubectl run --generator=run-pod/v1 <name> --image=<image>

Then it should run successfully. (they should have just defaulted the generator to run-pod/v1 to avoid this confusion and/or just encouraged the use of create).

However, based on @soltysh answer, it sounds as if they are now recommending 'create' over 'run.'

Solution 5:

To run a pod, this simple command is enough:

kubectl run --restart=Never <name> --image=<image>

Check https://www.k8s-school.fr/resources/blog/1-kubectl-run-deprecated/#pod for additional informations.