Merge branch 'skia/deploy_in_ci' into 'master'

gitlab-ci: deploy with Gitlab CI/CD

This MR is a proof-of-concept for deploying the Sith using Gitlab CI/CD. It leverage the CI variable to use a private key that is deployed for the `sith` user of `ae-web`. The `prod.sh` script shall do the rest.

TODO before merge:
* [x] Ensure the private key variable is protected (currently done, but may change during development to be used on this branch)
* [x] Remove this branch from the `only:refs` list
* [x] Change `test_prod.sh` for the real script

See merge request ae/Sith!293

.gitlab-ci.yml

@@ -1,5 +1,6 @@
 stages:
   - test
+  - deploy
 
 # Installs and launch unittests
 unittests:
@@ -47,3 +48,40 @@ black:
   cache:
     paths:
       - .cache/pip_black
+
+deploy:
+  stage: deploy
+  before_script:
+    ##
+    ## Install ssh-agent if not already installed, it is required by Docker.
+    ## (change apt-get to yum if you use an RPM-based image)
+    ##
+    - 'command -v ssh-agent >/dev/null || ( apt-get update -y && apt-get install openssh-client -y )'
+
+    ##
+    ## Run ssh-agent (inside the build environment)
+    ##
+    - eval $(ssh-agent -s)
+
+    ##
+    ## Add the SSH key stored in SSH_PRIVATE_KEY variable to the agent store
+    ## We're using tr to fix line endings which makes ed25519 keys work
+    ## without extra base64 encoding.
+    ## https://gitlab.com/gitlab-examples/ssh-private-key/issues/1#note_48526556
+    ##
+    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
+
+    ##
+    ## Create the SSH directory and give it the right permissions
+    ##
+    - mkdir -p ~/.ssh
+    - chmod 700 ~/.ssh
+  script:
+    - ssh -o StrictHostKeyChecking=accept-new sith@ae-web $SITH_PROD_SCRIPT_PATH
+  environment:
+    name: prod
+    url: https://ae.utbm.fr
+  only:
+    refs:
+      - master
+  when: on_success