Drone CI: Build and publish (#1)

* Build and publish to ghcr with drone CI

* Sign drone config file

* Updated build step name

* Allow publish on this branch for testing

* Try set image source label to ghcr

* Update label image source structure

* Remove git suffix of container source

* Remove ci branch from allowed publish branches

.drone.yml

@@ -0,0 +1,40 @@
+---
+kind: pipeline
+type: docker
+name: Build and publish
+
+platform:
+  os: linux
+  arch: amd64
+
+steps:
+  - name: build
+    image: golang
+    commands:
+      - make build
+
+  - name: Build and publish docker image
+    image: plugins/docker
+    settings:
+      registry: ghcr.io
+      repo: ghcr.io/kevinmidboe/planetposen-mail
+      dockerfile: Dockerfile
+      username:
+        from_secret: GITHUB_USERNAME
+      password:
+        from_secret: GITHUB_PASSWORD
+      tags: latest
+    when:
+      event:
+        include:
+          - push
+        exclude:
+          - pull_request
+      branch:
+        - master
+
+---
+kind: signature
+hmac: 92fdb188c7743e4b3c82a5cb8167abb86ab65508e03bf76273e1193692b439aa
+
+...

Dockerfile

@@ -1,6 +1,8 @@
 # Build the project
 FROM golang:1.19 as builder
 
+LABEL org.opencontainers.image.source="https://github.com/KevinMidboe/planetposen-mail"
+
 WORKDIR /go/src/github.com/kevinmidboe/planetposen-mail
 ADD . .