gh-release

#!/bin/bash
#
# This script reads the latest release on GitHub, checks out its
# tag and runs a build command (defaults to `make archive`) with GOOS / GOARCH
# combinations defined in the script. After that, it attaches the resulting
# tarball to the release.

set -eu -o pipefail

TARGETS=("GOOS=linux  GOARCH=386" \
         "GOOS=linux  GOARCH=arm" \
         "GOOS=linux  GOARCH=amd64" \
         "GOOS=darwin GOARCH=amd64")

get_repo() {
  local url=$(git config --get remote.origin.url)
  if echo "$url" | grep -s '^https://' >/dev/null; then
    echo "$url" | cut -d/ -f4,5
  else
    echo "$url" | cut -d: -f2 | cut -d. -f1
  fi
}

fatal() {
  echo "$@" >&2
  exit 1
}

if [[ -z "${GITHUB_TOKEN:-}" ]] && [[ ! -e "$HOME/.github-token" ]]; then
  fatal "Either GITHUB_TOKEN env var or ~/.github-token required"
fi

readonly TOKEN=${GITHUB_TOKEN-$(cat ~/.github-token)}
readonly CMD=${*-make archive}
readonly REPO=$(get_repo)
[[ -z "$REPO" ]] && fatal "Couldn't find remote url, no git repo?"

readonly NAME=$(echo "$REPO" | cut -d/ -f2)
readonly OLD_BRANCH=$(git rev-parse --abbrev-ref HEAD)

readonly LATEST=$(curl -s -L "https://api.github.com/repos/$REPO/releases" | \
  jq -r '.[0]' 2> /dev/null)

readonly TAG=$(echo "$LATEST" | jq -r '.tag_name')
[[ "$TAG" == "null" ]] \
  && fatal "Couldn't find tag for latest release. Check if any releases exists."

UPLOAD_URL=$(echo "$LATEST" | jq -r '.upload_url' | sed 's/{?name.*}//')

trap 'git checkout -q $OLD_BRANCH' EXIT
git checkout -q "$TAG" > /dev/null

for vars in "${TARGETS[@]}"; do
  declare $vars
  name="$NAME-$TAG.$GOOS-$GOARCH.tar.gz"
  if echo "$LATEST" | jq -e ".assets[]|select(.name == \"$name\")" > /dev/null
  then
    echo "Asset $name already exists, skipping"
    continue
  fi
  echo "Building $name"
  make clean
  GOOS=$GOOS GOARCH=$GOARCH $CMD
  [ -e "$name" ] \
    || fatal "Build artifact not found. Make sure build command builds $name."

  status=$(curl -s -o /dev/null -H 'Content-type: application/gzip' \
    -u "$TOKEN:x-oauth-basic" "$UPLOAD_URL?name=$name" \
    --data-binary "@$name" -w '%{http_code}')

  [[ "$status" == "201" ]] \
    || fatal "Couldn't upload $name, status code $status"
done