Kubernetes integration does not work in gitlab runner image entrypoint

Summary

Kubernetes integration does not work in gitlab runner image entrypoint.

Steps to reproduce

A base image for gitlab runner job that is build from the Dockerfile:

FROM alpine:3.9

RUN apk add --no-cache --virtual .runtime-utils curl bash git make

ENV KUBECTL_VERSION v1.14.2

RUN set -ex \
    && curl -sSL https://storage.googleapis.com/kubernetes-release/release/${KUBECTL_VERSION}/bin/linux/amd64/kubectl -o /usr/local/bin/kubectl \
    && chmod +x /usr/local/bin/kubectl

COPY docker-entrypoint.sh /opt/ci/

ENTRYPOINT ["/opt/ci/docker-entrypoint.sh"]

docker-entrypoint.sh, contains the following script:

#!/usr/bin/env bash
set -euo pipefail

echo "--> kubectl version"
kubectl version

exec "$@"
exit $?

kubectl version shows both local kubectl tool version as well as the server version. To get server version, it connects to the server with credentials that should be prepared by GitLab Kubernetes integration.

.gitlab-ci.yml looks like this:

stages:
  - debug

debug:
  stage: debug
  image: ${CI_IMAGE} # image build from Dockerfile above
  script:
  - echo "Ok"
  environment:
    name: dev

This job fails with the message:

# ...
section_start:1559767529:build_script
--> kubectl version
Error loading config file " LS0tLS1CRUdJTiBDRVJUS...
contexts": open  LS0tLS1CRUdJTiBDRVJUS...
contexts: file name too long
Error loading config file " [MASKED]
": open  [MASKED]
: file name too long
section_end:1559767531:build_script
# ...

It outputs the full Kubernetes CA certificate (I replaced it with LS0tLS1CRUdJTiBDRVJUS... it for brevity).

Note that if we remove kubectl version command from the Docker entrypoint, and put it into the script section to .gitlab-ci.yaml like this:

stages:
  - debug

debug:
  stage: debug
  image: ${CI_IMAGE} # image build from Dockerfile above
  script:
  - kubectl version
  environment:
    name: dev

Then everything works just fine (which means Kubernetes integration works fine in this case).

What is the current bug behavior?

Script in Docker entrypoint of the gitlab runner base image is not geting proper kubeconfig to connect to the Kubernetes.

What is the expected correct behavior?

GitLab Kubernetes integration should provide correct kubeconfig to the Docker entrypoint script.

Other info

I'm using hosted gitlab.com.