Added gitlab docs

ci/gitlab/README.md

@@ -0,0 +1,60 @@
+# Install the Gitlab Pipeline
+
+## Create a “Repository Access Token” for Pixee
+
+1. Open your repo in Gitlab and click on `Settings` -> `Access Token`. 
+
+<img src="../assets/gitlab/settings_access_tokens.png" width=200/>
+
+2. Click the `Add New Token` button 
+
+<img src="../assets/gitlab/add_token.png" width=600/>
+
+3. Give the token a name like `Pixee` and select the API scope.
+
+<img src="../assets/gitlab/scopes.png" width=600/>
+
+4. Copy the token for the next step> 
+
+<img src="../assets/gitlab/copy_token.png" width=600/>
+
+## Create a “Repository Access Token” for Pixee
+
+1. Open your repo in Gitlab and click on `Settings` -> `CI/CD`.
+
+<img src="../assets/gitlab/settings_cicd.png" width=200/>
+
+2. Expand `Variables` -> `add variable` and create a new one with the key `GITLAB_API_TOKEN_PIXEE` and the value from the step above.
+
+<img src="../assets/gitlab/add_var.png" width=300/>
+
+## Add the `Pixee` step to your pipeline
+
+``` YAML
+pixee:
+  image: codemodder/pixee-ci-gitlab:0.0.2
+  script: 
+    - echo ONMERGE
+    - echo $CI_MERGE_REQUEST_IID
+    - echo $CI_MERGE_REQUEST_TARGET_BRANCH_NAME
+    - echo $CI_DEFAULT_BRANCH
+    - FILES=$(git --no-pager diff --name-only $CI_MERGE_REQUEST_DIFF_BASE_SHA...HEAD)
+    - echo $FILES
+    - 'FILESTR=$(echo "$FILES" | sed "s/^/**/" | tr "\n" ",")'
+    - echo $FILESTR
+    - echo $API_TOKEN
+    - pixee fix --apply-fixes --path-include $FILESTR $CI_PROJECT_DIR
+    - wget https://local.l33t.af/pipeline.py -O /pixee/gitlab/pipeline.py
+    - wget https://local.l33t.af/requirements.txt -O /pixee/gitlab/requirements.txt
+    - pip install -r /pixee/gitlab/requirements.txt
+    - python /pixee/gitlab/pipeline.py ./results.codetf.json
+
+  artifacts:
+    paths:
+      - results.codetf.json
+  rules:
+    # pipeline should run on merge request to release branch
+    - if: $CI_PIPELINE_SOURCE == 'merge_request_event' && $CI_MERGE_REQUEST_TARGET_BRANCH_NAME == $CI_DEFAULT_BRANCH
+      when: always
+    - when: never
+```