ci: use KO for publishing docker image

.github/workflows/docker.yml

@@ -5,38 +5,19 @@ on:
   push:
     branches:
       - 'master'
+      - 'ko'
     tags:
       - 'v*'
 
-env:
-  REGISTRY: ghcr.io
-  IMAGE_NAME: ${{ github.repository }}
-
 jobs:
-  docker:
+  publish:
+    name: Publish
     runs-on: ubuntu-latest
     steps:
-      -
-        name: Checkout
-        uses: actions/checkout@v4
-      -
-        name: Login to registry
-        uses: docker/login-action@v3
-        with:
-          registry: ${{ env.REGISTRY }}
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-      -
-        name: Docker meta
-        id: meta
-        uses: docker/metadata-action@v5
+      - uses: actions/setup-go@v5
         with:
-          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
-      -
-        name: Build and push
-        uses: docker/build-push-action@v5
-        with:
-          context: .
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+          go-version: '1.22.x'
+      - uses: actions/checkout@v3
+
+      - uses: ko-build/[email protected]
+      - run: ko build ./cmd/gdu

Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/library/golang:1.20 as builder
+FROM docker.io/library/golang:1.22 as builder
 
 WORKDIR /app