Gitlab CI/CD fails to build docker image
It looks like that the docker login and the docker build were done by different users. If a docker login is performed, then a ~/.docker directory will be created in the namespace of user X, if the build is done by user Y then the latter user does not have a .docker folder and is not authorized to pull the image. One could verify this by echo $USER in the pipeline, in this case gitlab-ci.yaml to check this.