Add pipeline to automatically update flakes

.gitlab-ci.yml

@@ -20,6 +20,9 @@ test:
   stage: test
   script:
     - nix flake check
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "schedule"
+      when: never
 
 deploy:
   stage: deploy
@@ -32,4 +35,33 @@ deploy:
     # Deploy everything
     - nix develop --command deploy
   rules:
+    - if: $CI_PIPELINE_SOURCE == "schedule"
+      when: never
     - if: $CI_COMMIT_BRANCH == "master"
+
+
+check updates:
+  stage: test
+  script:
+    # Prepare git access
+    - nix-env -iA nixos.openssh
+    - eval "$(ssh-agent -s)"
+    - chmod 0600 $SSH_UPDATE_KEY
+    - ssh-add $SSH_UPDATE_KEY
+    - mkdir -p ~/.ssh
+    - chmod 700 ~/.ssh
+    - ssh-keyscan git.lewd.wtf >> ~/.ssh/known_hosts
+    - chmod 644 ~/.ssh/known_hosts
+    - git config --global user.name "NixOS Flake Update"
+    - git config --global user.email "git@lewd.wtf"
+    - git remote rm origin && git remote add origin "git@git.lewd.wtf:${CI_PROJECT_PATH}.git"
+    # Update flakes
+    - nix flake update
+    # Push changes
+    - git checkout -b flakes_update
+    - git add .
+    - git commit -m 'Update NixOS Flakes'
+    - git push --set-upstream origin flakes_update -o merge_request.create
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "schedule"
+