feat: add github actions support for building binaries

The bulk of the work for Github Actions happens in build.sh.
Additional platforms/architectures need to be specified in that file.

.github/workflows/go.yml

@@ -0,0 +1,20 @@
+name: build releases
+
+on:
+  release:
+    types: [published]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.16
+
+    - name: build binaries
+      run: GITHUB_TOKEN=${{ secrets.GITHUB_TOKEN }} ./build.sh

build.sh

@@ -1,15 +1,28 @@
 #!/bin/sh
 
-GIT_TAG=$(git tag | tail -1); GOOS=darwin GOARCH=arm64 go build -o arm64-macos-sb -a -ldflags="-X 'sb/cmd.AppVersion=$GIT_TAG'"
+# GITHUB_EVENT_PATH documented here:
+# https://docs.github.com/en/actions/reference/environment-variables#default-environment-variables
+GIT_TAG=$(jq .release.tag_name < "${GITHUB_EVENT_PATH}" | sed -e 's/"//g')
+UPLOAD_URL=$(jq .release.upload_url < "${GITHUB_EVENT_PATH}" | sed -e 's/"//g' | cut -d "{" -f 1)
+RELEASES="arm64-darwin-sb amd64-linux-sb amd64-darwin-sb"
 
-GIT_TAG=$(git tag | tail -1); GOOS=darwin GOARCH=amd64 go build -o amd64-macos-sb -a -ldflags="-X 'sb/cmd.AppVersion=$GIT_TAG'"
+upload_file() {
+    NAME=$1
 
-GIT_TAG=$(git tag | tail -1); GOOS=linux GOARCH=amd64 go build -o amd64-linux-sb -a -ldflags="-X 'sb/cmd.AppVersion=$GIT_TAG'"
+    zip "${NAME}.zip" "${NAME}"
+    curl -H "Accept: application/vnd.github.v3+json" \
+         -H "Authorization: Bearer ${GITHUB_TOKEN}" \
+         -H "Content-Type: application/zip" \
+         --data-binary "@${NAME}.zip" \
+         "${UPLOAD_URL}?name=${NAME}.zip"
+}
 
-zip arm64-macos-sb.zip arm64-macos-sb
+for PLATFORM in ${RELEASES}; do
+    GOOS=$(echo "${PLATFORM}" | cut -d - -f 2) \
+    GOARCH=$(echo "${PLATFORM}" | cut -d - -f 1) \
+    go build -o "${PLATFORM}" -a -ldflags="-X 'sb/cmd.AppVersion=${GIT_TAG}'"
 
-zip amd64-macos-sb.zip amd64-macos-sb
-
-zip amd64-linux-sb.zip amd64-linux-sb
-
-rm *-sb
+    if [ "${UPLOAD_URL}" != null ]; then
+        upload_file "${PLATFORM}"
+    fi
+done