title: Exporting environment variables from one stage to the next in GitLab CI
body: <p>Is there a way to <code>export</code> environment variables from one stage to the next in GitLab CI? I'm looking for something similar to the <a href="https://docs.gitlab.com/ce/user/project/pipelines/job_artifacts.html#introduction-to-job-artifacts" rel="noreferrer">job artifacts</a> feature, only for environment variables instead of files.</p>
  <p>Let's say I'm configuring the build in a <code>configure</code> stage and want to store the results as (secret, protected) environment variables for the next stages to use. I could safe the configuration in files and store them as job artifacts but I'm concerned about secrets being made available in files than can be downloaded by everyone.</p>