Add drone build configuration

Author: djmaze

.drone.yml

@@ -0,0 +1,93 @@
+kind: pipeline
+name: amd64
+
+platform:
+  os: linux
+  arch: amd64
+
+steps:
+  - name: build
+    image: plugins/docker
+    settings:
+      auto_tag: true
+      auto_tag_suffix: amd64
+      repo: mazzolino/shepherd
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+    when:
+      event:
+        exclude:
+          - pull_request
+
+---
+kind: pipeline
+name: arm
+
+platform:
+  os: linux
+  arch: arm
+
+steps:
+  - name: build
+    image: plugins/docker:linux-arm
+    settings:
+      auto_tag: true
+      auto_tag_suffix: arm
+      repo: mazzolino/shepherd
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+    when:
+      event:
+        exclude:
+          - pull_request
+
+---
+kind: pipeline
+name: arm64
+
+platform:
+  os: linux
+  arch: arm64
+
+steps:
+  - name: build
+    image: plugins/docker:linux-arm64
+    settings:
+      auto_tag: true
+      auto_tag_suffix: arm64
+      repo: mazzolino/shepherd
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+    when:
+      event:
+        exclude:
+          - pull_request
+---
+kind: pipeline
+name: manifest
+
+steps:
+  - name: manifest
+    image: plugins/manifest:1
+    settings:
+      spec: manifest.tmpl
+      auto_tag: true
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+      platforms:
+        - linux/amd64
+        - linux/arm
+        - linux/arm64
+
+depends_on:
+  - amd64
+  - arm
+  - arm64

manifest.tmpl

@@ -0,0 +1,18 @@
+image: mazzolino/shepherd:{{#if build.tag}}{{trimPrefix build.tag "v"}}{{else}}latest{{/if}}
+{{#if build.tags}}
+tags:
+{{#each build.tags}}
+  - {{this}}
+{{/each}}
+{{/if}}
+manifests:
+  -
+    image: mazzolino/shepherd:{{#if build.tag}}{{trimPrefix build.tag "v"}}-{{/if}}amd64
+    platform:
+      architecture: amd64
+      os: linux
+  -
+    image: mazzolino/shepherd:{{#if build.tag}}{{trimPrefix build.tag "v"}}-{{/if}}arm
+    platform:
+      architecture: arm
+      os: linux