Git CI authentication with SSH keys

deploy-ci.sh

#!/usr/bin/env bash

# References:
# https://docs.travis-ci.com/user/environment-variables
#
# Inspired by:
# https://gist.github.com/willprice/e07efd73fb7f13f917ea
# But using SSH keys instead of Personal Access Token:
# https://gist.github.com/alexilyaev/2672fe6d99756377fbffaabad6db1f45

# https://misc.flogisoft.com/bash/tip_colors_and_formatting
ANSI_GREEN_BOLD="\033[32;1m"
ANSI_RED="\033[31m"
ANSI_BLUE="\033[34m"
ANSI_RESET="\033[0m"
targetRepoSshUrl="git@github.com:${TRAVIS_REPO_SLUG}.git"
ciBranch="$TRAVIS_BRANCH"

function log() {
  local msg="$1"
  echo -e "\n${ANSI_GREEN_BOLD}LOG:${ANSI_RESET} ${ANSI_BLUE}$msg${ANSI_RESET}"
}

function logError() {
  local msg="$1"
  echo -e "\n${ANSI_RED}ERROR: $msg${ANSI_RESET}"
}

log "Running deploy-ci script..."

# Immediately exit if we're in a PR build.
if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then
  log "This is a PR build, nothing to do."
  exit 0
fi

# Use an SSH connection instead of the default read-only https connection.
function setupRepo() {
  log "Setup Git SSH connection"

  # Ensure proper branch matching when multiple remotes are set
  git config --global checkout.defaultRemote origin

  git remote rm origin || true
  git remote add origin "$targetRepoSshUrl"
  git fetch --all
}

function mergeFromTo() {
  local fromBranch=$1
  local targetBranch=$2

  log "Switch to branch '$targetBranch'"
  git checkout "$targetBranch"

  if [ "$?" = "1" ]; then
    logError "Failed to checkout branch: '$targetBranch'"
    return 1
  fi

  # Must use --no-ff, otherwise GitHub won't emit any events when we 'push',
  # and Vercel won't deploy our branch.
  # Must also provide a commit message when using '--no-ff'.
  log "Merge '$fromBranch' into '$targetBranch'"
  git merge --no-ff "$fromBranch" -m "Merge '$fromBranch' into '$targetBranch'"

  if [ "$?" = "1" ]; then
    logError "Failed to merge '$fromBranch' into '$targetBranch'"
    return 1
  fi

  # Using '--force' in case the branch was tampered with manually.
  log "Push '$targetBranch'"
  git push --force

  if [ "$?" = "1" ]; then
    logError "Failed to push branch: '$targetBranch'"
    return 1
  fi
}

if [ "$ciBranch" == "master" ]; then
  targetBranch="staging"
  log "'$ciBranch' branch updated, merge and push to '$targetBranch'"

  setupRepo || exit 1
  mergeFromTo "origin/$ciBranch" "$targetBranch" || exit 1
fi

log "Finished deploy-ci script."

git-ci-ssh.md

Git CI authentication with SSH keys

SSH Keys Setup

• The steps from semantic-release - Git authentication with SSH keys are relevant, but...
  • Travis expects an RSA private key, on modern macOS, need to output a PEM format:
    travis-ci/travis.rb#267 (comment)
  • We don't have to encrypt and stuff, can just add to Travis repo Settings > SSH Key.