Feature request: Cache base image in repository

[dbadura]

Actual behavior
Currently Kaniko fetch base image every time I build, even I have repository cache turn on.
This behavior heavily depends on internet speed, which can be pretty slow (e.g.: mobile internet).

There is a solution with warmer, but in our case add additional overhead which we want to bypass.
Especially that repository is used as cache.

Expected behavior
I would like to add some flag like: --cache-base-image to prevent kaniko from fetching base image every time I am building something and make kaniko to use cache from repository.

To Reproduce
Steps to reproduce the behavior:

1. Run this script:

docker run  --publish 5000:500 --network host --rm --name registry --detach \
  registry:2 /etc/docker/registry/config.yml

PWD=$(pwd)
IP="${IP:-127.0.0.1}"
docker run -v "${PWD}":/workspace \
  --network host \
  --rm \
  eu.gcr.io/kyma-project/tpi/kaniko-executor:1.9.0-a550386f \
  --insecure \
  --skip-tls-verify \
  --verbosity debug \
  --skip-unused-stages \
  --log-format=text \
  --cache=true \
  --force \
  --destination="${IP}":5000/default-function-001-v2:5b759bc8169808cba87125ac0eceef83705f0a985f04a5f9ce4c051158d5c2c4 \
  --context=dir:///workspace

Additional Information

• Dockerfile, can be any

ARG base_image=eu.gcr.io/kyma-project/function-runtime-python39:f94d14f3
FROM ${base_image}
USER root
ENV KUBELESS_INSTALL_VOLUME=/kubeless

COPY /src/requirements.txt $KUBELESS_INSTALL_VOLUME/requirements.txt
RUN pip install -r $KUBELESS_INSTALL_VOLUME/requirements.txt
COPY /src $KUBELESS_INSTALL_VOLUME

RUN rm -rf /etc/pip.conf

USER 1000

• Build Context
  Please provide or clearly describe any files needed to build the Dockerfile (ADD/COPY commands)
  empty requirements.txt and handler.py with:

def main(event, context):
    return "hello world"

in src dir

• Kaniko Image (fully qualified with digest): 1.9.0-a550386f

Triage Notes for the Maintainers

Description	Yes/No
Please check if this a new feature you are proposing
Please check if the build works in docker but not in kaniko
Please check if this error is seen when you use --cache flag
Please check if your dockerfile is a multistage dockerfile