I am trying to use slack to notify when a build is complete or if a build fails on GitlabCI. What I also wanna be able to do is append a predefined environment variable $GITLAB_CI_COMMIT_TITLE so along with the build notification I also know which build with what commit has completed/failed

This works

"curl -X POST -H 'Content-type: application/json' --data '{\"text\":\" Client Staging build complete. \n\"}'
https://hooks.slack.com/services/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"

But this doesnt

"curl -X POST -H 'Content-type: application/json' --data-binary '{
      "'"$CI_COMMIT_TITLE"'" \n\"}'

The second command works, but it doesnt export the value of the variable, I just see '$CI_COMMIT_TITLE' in the slack notification.