also install hex in ci

.gitlab-ci.yml

@@ -19,16 +19,21 @@ test-frontend:
 
 backend-sobelow:
   stage: test
-  image: elixir:1.9-alpine
+  image: elixir:1.9
   only:
     changes:
       - backend/*
   before_script:
     - cd backend
   script:
+    - mix local.hex
     - mix deps.get
     - mix deps.compile
     - mix sobelow --config
+  cache:
+    paths:
+      - backend/deps/
+      - backend/build/
 
 deploy-backend-develop:
   stage: deploy

backend/README.md

@@ -4,7 +4,7 @@
 
 - This project requires Elixir >= 1.9.
 - Run with `SKIP_CRAWL=true` to just run the server (useful for working on the API without also crawling)
-- This project is automatically scanned for potential vulnerabilities with [Sobelow](https://sobelow.io/).
+- The backend is automatically scanned for potential vulnerabilities with [Sobelow](https://sobelow.io/).
 
 ## Deployment