Publish binaries for every platform with each release

.github/workflows/ci.yml

@@ -33,6 +33,20 @@ jobs:
           make tidy
           git diff --exit-code -- go.mod go.sum
 
+  platforms:
+    name: builds for every platform
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+      # The same script the release runs, so a tag is never the first time a
+      # target is built.
+      - run: ./scripts/build-release.sh dev dist
+      - name: the checksums match the files
+        run: cd dist && sha256sum -c SHA256SUMS
+
   race:
     name: race detector
     runs-on: ubuntu-latest

.github/workflows/release.yml

@@ -127,3 +127,41 @@ jobs:
           fi
 
           gh release create "$TAG" --verify-tag --title "$TAG" "${notes[@]}" "${flags[@]}"
+
+  binaries:
+    name: publish binaries
+    # Archives for every platform, for hosts with no Docker and no Go: Windows
+    # servers, 32-bit ARM, FreeBSD. After the release page exists, because they
+    # are attached to it.
+    needs: release
+    if: startsWith(github.ref, 'refs/tags/v')
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Build every platform
+        env:
+          TAG: ${{ github.ref_name }}
+        run: ./scripts/build-release.sh "${TAG#v}" dist
+
+      # A binary that does not report the tag was not stamped with it, and
+      # would be published as a release it is not.
+      - name: The Linux build reports this release
+        env:
+          TAG: ${{ github.ref_name }}
+        run: |
+          tar -xzf "dist/certpilot-agent_${TAG#v}_linux_amd64.tar.gz" -C "$RUNNER_TEMP"
+          got=$("$RUNNER_TEMP/certpilot-agent_${TAG#v}_linux_amd64/certpilot-agent" version)
+          [ "$got" = "${TAG#v}" ] || { echo "binary says $got, tag is $TAG"; exit 1; }
+
+      - name: Attach them to the release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG: ${{ github.ref_name }}
+        # --clobber so re-running a tag's workflow replaces its files.
+        run: gh release upload "$TAG" dist/* --clobber

README.md

@@ -17,6 +17,10 @@ the key does not, and there is no code path that would let it.
 go install github.com/certpilot/certpilot-agent/cmd@latest
 ```
 
+No Go or Docker on the host? Each [release](https://github.com/certpilot/certpilot-agent/releases)
+has a static binary for Linux (amd64, arm64, armv7, 386), Windows (amd64, arm64),
+macOS and FreeBSD, with a `SHA256SUMS` file to check it against.
+
 ```
 docker run --rm -v certpilot-agent:/var/lib/certpilot-agent \
     ghcr.io/certpilot/agent:latest --help

scripts/build-release.sh

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+#
+# Build the agent for every platform it is released for.
+#
+#   ./scripts/build-release.sh 0.2.4 dist     stamp 0.2.4, write archives to dist/
+#   ./scripts/build-release.sh dev dist       unstamped, as CI builds it
+#
+# One script for CI and for the release, so a tag is never the first time a
+# target is built. Each target is a static binary (CGO off) in an archive with
+# the licence and README, and SHA256SUMS lists them all.
+#
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+version="${1:?usage: build-release.sh VERSION OUTDIR}"
+out="${2:?usage: build-release.sh VERSION OUTDIR}"
+
+# os/arch[/goarm]
+targets=(
+  linux/amd64 linux/arm64 linux/arm/7 linux/386
+  windows/amd64 windows/arm64
+  darwin/amd64 darwin/arm64
+  freebsd/amd64
+)
+
+# An unstamped build keeps the -dev default compiled into the source, rather
+# than claiming a release number it is not.
+ldflags="-s -w"
+if [ "$version" != dev ]; then
+  ldflags="$ldflags -X github.com/certpilot/certpilot-agent.Version=$version"
+fi
+
+rm -rf "$out"
+mkdir -p "$out"
+out="$(cd "$out" && pwd)"
+work="$(mktemp -d)"
+trap 'rm -rf "$work"' EXIT
+
+for target in "${targets[@]}"; do
+  IFS=/ read -r goos goarch goarm <<<"$target"
+  name="certpilot-agent_${version}_${goos}_${goarch}${goarm:+v$goarm}"
+  bin=certpilot-agent
+  [ "$goos" = windows ] && bin=certpilot-agent.exe
+
+  dir="$work/$name"
+  mkdir -p "$dir"
+  CGO_ENABLED=0 GOOS="$goos" GOARCH="$goarch" GOARM="${goarm:-}" \
+    go build -trimpath -ldflags="$ldflags" -o "$dir/$bin" ./cmd/
+  cp LICENSE README.md "$dir/"
+
+  if [ "$goos" = windows ]; then
+    (cd "$work" && zip -qr "$out/$name.zip" "$name")
+  else
+    tar -C "$work" -czf "$out/$name.tar.gz" "$name"
+  fi
+  echo "built $name"
+done
+
+sum() { if command -v sha256sum >/dev/null; then sha256sum "$@"; else shasum -a 256 "$@"; fi; }
+(cd "$out" && sum certpilot-agent_* > SHA256SUMS)
+echo "wrote $(ls "$out" | wc -l | tr -d ' ') files to $out"