Adding Docker image build to Drone CI configuration.

.drone.yml

@@ -30,3 +30,22 @@ steps:
           - pull_request
       branch:
         exclude: master
+  - name: docker-build
+    # https://github.com/drone/drone-plugin-index/blob/main/plugins/docker/original.md
+    image: plugins/docker
+    when:
+      branch:
+        - master
+      event:
+        - push
+    settings:
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_token
+      repo:
+        from_secret: docker_repo
+      tags:
+        - latest
+        - ${DRONE_COMMIT_SHA:0:10}
+        - ${DRONE_TAG}