GHA workflow updates

- Build from a matrix of platform-arch pairs
- Add helper function to automate cross-compilation
- Add PLATFORMS to platforms.bzl identifying what to build for
- Create a new release on tags

.github/workflows/build.yml

@@ -0,0 +1,34 @@
+name: Build & Release
+run-name: Build & Release
+on: push
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        goos: [linux, darwin]
+        goarch: [arm64, amd64]
+    runs-on: ${{ matrix.goos }}
+    steps:
+    - name: Check out smart-dns-updater
+      uses: actions/checkout@v4
+    - run: |
+        bazelisk build //:smart-dns-updater_${{ matrix.goos }}_${{ matrix.goarch }}
+    - name: Upload artifact
+      uses: actions/upload-artifact@v4
+      with:
+        name: smart-dns-updater_${{ matrix.goos }}_${{ matrix.goarch }}
+        path: bazel-bin/smart-dns-updater_${{ matrix.goos }}_${{ matrix.goarch }}_/smart-dns-updater_${{ matrix.goos }}_${{ matrix.goarch }}
+        if-no-files-found: error
+
+  release:
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Release
+        uses: softprops/action-gh-release@v2
+        # Only release on tags
+        if: startsWith(github.ref, 'refs/tags/')
+        with:
+          files: |
+            bazel-bin/smart-dns-updater_*_/smart-dns-updater_*

.github/workflows/test.yml

@@ -2,13 +2,15 @@ name: Test
 run-name: Test
 on:
   push:
+    branches: [main]
   pull_request:
     paths:
       - "!README.md"
       - "!LICENSE"
 
 jobs:
-  Test:
+  test:
+    name: Test
     runs-on: ubuntu-latest
     steps:
       - name: Check out smart-dns-updater

BUILD.bazel

@@ -1,13 +1,18 @@
 load("@gazelle//:def.bzl", "gazelle")
-load("@rules_go//go:def.bzl", "go_binary", "go_library", "go_test")
+load("@rules_go//go:def.bzl", "go_library", "go_test")
+load("helper.bzl", "cross_compile_binary")
+load("platforms.bzl", "PLATFORMS")
+
+# Name of the binary
+NAME = "smart-dns-updater"
 
 # gazelle:prefix github.com/imeyer/smart-dns-updater
 gazelle(name = "gazelle")
 
 go_library(
-    name = "smart-dns-updater_lib",
+    name = "{}_lib".format(NAME),
     srcs = ["main.go"],
-    importpath = "github.com/imeyer/smart-dns-updater",
+    importpath = "github.com/imeyer/{}".format(NAME),
     visibility = ["//visibility:private"],
     x_defs = {
         "version": "{STABLE_VERSION}",
@@ -22,17 +27,18 @@ go_library(
     ],
 )
 
-go_binary(
-    name = "smart-dns-updater",
-    embed = [":smart-dns-updater_lib"],
-    visibility = ["//visibility:public"],
-)
+# Create go_binary targets for each platform-arch combination
+[cross_compile_binary(
+    name = NAME,
+    goarch = goarch,
+    goos = goos,
+) for (goos, goarch) in PLATFORMS]
 
 go_test(
-    name = "smart-dns-updater_test",
+    name = "{}_test".format(NAME),
     size = "small",
     srcs = ["main_test.go"],
-    embed = [":smart-dns-updater_lib"],
+    embed = [":{}_lib".format(NAME)],
     deps = [
         "@com_github_miekg_dns//:dns",
         "@com_github_stretchr_testify//assert",

helper.bzl

@@ -0,0 +1,13 @@
+"""Helper module to create binaries per PLATFORM-ARCH combination"""
+
+load("@rules_go//go:def.bzl", "go_binary")
+
+# Function to create a go_binary target for each platform-arch combination
+def cross_compile_binary(name, goos, goarch):
+    go_binary(
+        name = "{}_{}_{}".format(name, goos, goarch),
+        embed = [":{}_lib".format(name)],
+        goarch = goarch,
+        goos = goos,
+        visibility = ["//visibility:public"],
+    )

platforms.bzl

@@ -0,0 +1,9 @@
+"""Define platform, arch pairs to build"""
+
+# Define the matrix of platforms and architectures
+PLATFORMS = [
+    ("linux", "amd64"),
+    ("linux", "arm64"),
+    ("darwin", "amd64"),
+    ("darwin", "arm64"),
+]