Improve CI

Add more tests to the CI, including a docker build test, and add the
generation and publication of a new docker image on master and tags

.drone.yml

@@ -1,16 +1,88 @@
+---
+# Test building the code and docker image
 kind: pipeline
 type: docker
-name: Tests
+name: test-build
 
 steps:
-- name: test
+- name: go-test
   image: golang
   commands:
-  - cd tracker
-  - make build
-  - make test
+  - make -C tracker test
+  depends_on:
+
+- name: go-build
+  image: golang
+  commands:
+  - make -C tracker build
+  depends_on:
+
+- name: docker-build-only
+  image: thegeeklab/drone-docker-buildx
+  privileged: true
+  settings:
+    repo: git.faercol.me/faercol/public-ip-tracker
+    tags: latest
+    dry_run: true
+    platforms:
+      - linux/amd64
+      - linux/arm64
+  depends_on:
+  when:
+    branch:
+      exclude:
+        - master
+    event:
+      - push
+
+- name: docker-build-push
+  image: thegeeklab/drone-docker-buildx
+  privileged: true
+  settings:
+    repo: git.faercol.me/faercol/public-ip-tracker
+    registry: git.faercol.me
+    tags: latest
+    username:
+      from_secret: GIT_USERNAME
+    password:
+      from_secret: GIT_PASSWORD
+  depends_on:
+    - go-test
+    - go-build
+  when:
+    branch:
+      - master
+    event:
+      - push
 
 trigger:
   event:
     - push
     - tag
+
+---
+# On a tag, only build the related docker image
+kind: pipeline
+type: docker
+name: tag-release
+depends_on:
+  - test-build
+
+steps:
+- name: docker-push-tag
+  image: thegeeklab/drone-docker-buildx
+  privileged: true
+  settings:
+    registry: git.faercol.me
+    repo: git.faercol.me/faercol/public-ip-tracker
+    auto_tag: true
+    username:
+      from_secret: GIT_USERNAME
+    password:
+      from_secret: GIT_PASSWORD
+
+trigger:
+  event:
+    - tag
+
+...