ci: Build docker image

.gitlab-ci.yml

@@ -11,7 +11,7 @@ stages:
   - test
   - publish
 
-build_job:
+build:executable:
   stage: build
   image: crystallang/crystal:1.5
   script:
@@ -23,6 +23,22 @@ build_job:
     paths:
       - lib
 
+build:dockerimage:
+  stage: build
+  image: docker:20.10.16
+  services:
+    - docker:20.10.16-dind
+  need:
+    - build:executable
+  script:
+    - make build
+  artifacts:
+    paths:
+      - bin
+  cache:
+    paths:
+      - lib
+
 sast:
   stage: test