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Last pushed: 6 months ago
Short Description
Docker kubectl (without entrypoint)
Full Description

Supported tags and respective Dockerfile links

What is kubectl

kubectl is a CLI tool to control a cluster Kubernetes.

Usage

$ docker run --rm wernight/kubectl --help

Note: Entrypoint is set to kubectl so do not type wernight/kubectl kubectl.

Usage example 1

For example to access a local Kubernetes cluster you may run:

$ docker run --rm --net=host --user $UID \
    -v ~/.kube:/config/.kube \
    wernight/kubectl cluster-info
  • -net=host: (optional) allows to connect to a local Kubernetes cluster.
  • --user $UID: (optional) by default runs as random UID 2342, this allows to access your existing ~/.kube if you have one. As you can note, you can run kubectl as any UID/GID.
  • -v XXX:/config: (optional) allows to store its configuration and possibly access existing configuration. Note that /config will always be the directory containing .kube (it's the forced HOME directory). Can be read-only. Alternatively you can mount a Kubernetes service account for example: -v /var/run/secrets/kubernetes.io/serviceaccount:/var/run/secrets/kubernetes.io/serviceaccount:ro.

Usage example 2

Here we use the service-account, so this should work from within a Pod on your cluster as long as you've docker installed (and may be DOCKER_HOST set up properly):

$ docker run \
    -v /var/run/secrets/kubernetes.io/serviceaccount/:/var/run/secrets/kubernetes.io/serviceaccount/:ro \
    wernight/kubectl \
    -s https://kubernetes \
    --token="$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)" \
    --certificate-authority=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt \
    cluster-info

Note: Alternatively to using kube-dns, you can use environment variables set within Kubernetes containers: https://$KUBERNETES_SERVICE_HOST:$KUBERNETES_PORT_443_TCP_PORT.

Alias

You may setup an alias to run this is if you were running kubectl directly.
Here is a function POSIX-compatible that work for most shells:

kubectl () {
  docker run --rm -it --user $UID:$GID \
    -v /var/run/secrets/kubernetes.io/serviceaccount:/var/run/secrets/kubernetes.io/serviceaccount:ro \
    -w /code -v "$PWD":/code:ro \
    wernight/kubectl "$@"
}

Why use it

It's mostly meant to be used during continuous integration or as part of an automated build/deployment:

  • So that your machine (e.g. build server) doesn't need kubectl to be installed; only Docker.
  • To avoid kubectl config use-context and similar to affect your build and other projects' builds.

Feedbacks

Suggestions are welcome on our GitHub issue tracker.

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alexw23
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