ci: Add Drone configuration

.drone.yml

@@ -0,0 +1,55 @@
+---
+kind: pipeline
+type: docker
+name: default
+
+services:
+  - name: docker
+    image: docker:dind
+    privileged: true
+    volumes:
+      - name: dockersock
+        path: /var/run
+
+steps:
+  - name: "build:executable"
+    image: crystallang/crystal:1.5.0
+    volumes:
+      - name: cache
+        path: /stupid
+    commands:
+      # Debug
+      - pwd
+      - crystal version
+      - shards version
+      # Build
+      - make build
+
+  - name: "build:docker-image:"
+    image: docker:20.10.16-dind
+    volumes:
+      - name: dockersock
+        path: /var/run
+      - name: cache
+        path: /stupid
+    commands:
+      - apk install make
+      - make docker-build
+      - make docker-save > _artifacts/docker-image.tar
+
+  - name: "publish:docker-image"
+    image: docker:20.10.16-dind
+    volumes:
+      - name: dockersock
+        path: /var/run
+    commands:
+      - apk install make
+      - make docker-load < _artifacts/docker-image.tar
+      - make docker-push
+
+volumes:
+  - name: cache
+    temp: {}
+  - name: dockersock
+    temp: {}
+#