'Docker run' doesn't pass environment variables

Hi ,

This is an issue for reopening #18701 (closed)

image: docker:latest
services:
  - postgres:9.5

variables:
  POSTGRES_DB: test
  POSTGRES_USER: test
  POSTGRES_PASSWORD: test

stages:
- build
- release
- deploy

variables:
  CONTAINER_TEST_IMAGE: registry.example.com/my-group/my-project:tag
  CONTAINER_RELEASE_IMAGE: registry.example.com/my-group/my-project

before_script:
  - env
  - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN registry.example.com

build:
  stage: build
  script:
    - docker build --pull -t $CONTAINER_TEST_IMAGE .
    - docker run $CONTAINER_TEST_IMAGE ci/tests.sh
    - docker push $CONTAINER_TEST_IMAGE

When I run the env command inside the container (through the ci/tests.sh script), env vars are not set. I need to specify each env variable using -e flag. Gitlab variables are not pass when using docker run

If you have more that 10 env variables , this can be painfull.

Also , this implies to manage env variable at different locations ( In gitlab secret variable , and in the gitlab-ci script )

That would be great to have a param or something to pass every env variable so this does not require to maintain it at different location.