Update kubectl in the Docker images

[brandonkal]

kubectl is now four major versions behind. Please update it to the latest stable version. I'd love to start experimenting with this.

Also, tagging and releasing the first stage of this build would make it easier for others to choose the kubectl version they want.

[diafour]

Hello @brandonkal!

Please update it to the latest stable version.

I've updated kubectl to v1.17.4 and added alpine-3.11 build in PR #146.

Also, tagging and releasing the first stage of this build would make it easier for others to choose the kubectl version they want.

Can you be more specific, what kind of image that will be? A scratch image with shell-operator binary or something else?

One can replace kubectl binary in image with just one RUN command:

FROM flant/shell-operator:latest
RUN wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
    chmod +x /bin/kubectl
ADD hooks /hooks

I replace shell-operator binary for testing purposes in that manner. Is it a suitable solution for your task?

[brandonkal]

Thank you for the update. Regarding my second request, now that I think about it, it wouldn't make much sense to publish the go build container with the shell-operator binary.

A scratch container with the binary would probably be more interesting simply as a means to fetch only the built binary. But that is not really necessary now as the size of flant/shell-operator image is already pretty slim.