Command from docker image not passed through to pipeline

In my Dockerfile of an image that is based on node:12 I have the following lines to add a self signed certificate

RUN apt-get update && apt-get -yqq install ca-certificates
RUN mkdir -p /usr/local/share/ca-certificates/domain
COPY .docker/cert.crt /usr/local/share/ca-certificates/domain/
RUN update-ca-certificates --fresh

RUN yarn config set cafile /usr/local/share/ca-certificates/domain/cert.crt

When I also add RUN yarn config list I can see that this setting has been added successfully. Afterwards, I built and pushed my image to the registry.

However now, when I use it in my .gitlab-ci.yml and use yarn install I get an error that there’s a self-signed certificate in the chain.

When I use yarn config list inside the pipeline, it doesn’t show the cafile as if the settings set in the image are not used.

When I add yarn config set cafile /usr/local/share/ca-certificates/domain/cert.crt to the script part of my pipeline it works without problems which means

  1. That my image is built correctly, since it has the cert at the right location and it works if added manually
  2. That somehow the config is not persisted from the image to the pipeline

I checked the Dockerfile https://github.com/nodejs/docker-node/blob/master/12/stretch/Dockerfile and there’s no user set which could mean that it runs under different users, does it?

Why does it not work when adding the cert in the image already?

Source: Docker Questions