Add deploy script

deploy.sh

+#!/usr/bin/env bash
+set -o errexit #abort if any command fails
+me=$(basename "$0")
+
+help_message="\
+Usage: $me [-c FILE] [<options>]
+Deploy generated files to a git branch.
+
+Options:
+
+  -h, --help               Show this help information.
+  -v, --verbose            Increase verbosity. Useful for debugging.
+  -e, --allow-empty        Allow deployment of an empty directory.
+  -m, --message MESSAGE    Specify the message used when committing on the
+                           deploy branch.
+  -n, --no-hash            Don't append the source commit's hash to the deploy
+                           commit's message.
+  -c, --config-file PATH   Override default & environment variables' values
+                           with those in set in the file at 'PATH'. Must be the
+                           first option specified.
+
+Variables:
+
+  GIT_DEPLOY_DIR      Folder path containing the files to deploy.
+  GIT_DEPLOY_BRANCH   Commit deployable files to this branch.
+  GIT_DEPLOY_REPO     Push the deploy branch to this repository.
+
+These variables have default values defined in the script. The defaults can be
+overridden by environment variables. Any environment variables are overridden
+by values set in a '.env' file (if it exists), and in turn by those set in a
+file specified by the '--config-file' option."
+
+bundle exec middleman build --clean
+
+parse_args() {
+  # Set args from a local environment file.
+  if [ -e ".env" ]; then
+    source .env
+  fi
+
+  # Set args from file specified on the command-line.
+  if [[ $1 = "-c" || $1 = "--config-file" ]]; then
+    source "$2"
+    shift 2
+  fi
+
+  # Parse arg flags
+  # If something is exposed as an environment variable, set/overwrite it
+  # here. Otherwise, set/overwrite the internal variable instead.
+  while : ; do
+    if [[ $1 = "-h" || $1 = "--help" ]]; then
+      echo "$help_message"
+      return 0
+    elif [[ $1 = "-v" || $1 = "--verbose" ]]; then
+      verbose=true
+      shift
+    elif [[ $1 = "-e" || $1 = "--allow-empty" ]]; then
+      allow_empty=true
+      shift
+    elif [[ ( $1 = "-m" || $1 = "--message" ) && -n $2 ]]; then
+      commit_message=$2
+      shift 2
+    elif [[ $1 = "-n" || $1 = "--no-hash" ]]; then
+      GIT_DEPLOY_APPEND_HASH=false
+      shift
+    else
+      break
+    fi
+  done
+
+  # Set internal option vars from the environment and arg flags. All internal
+  # vars should be declared here, with sane defaults if applicable.
+
+  # Source directory & target branch.
+  deploy_directory=build
+  deploy_branch=gh-pages
+
+  #if no user identity is already set in the current git environment, use this:
+  default_username=${GIT_DEPLOY_USERNAME:-deploy.sh}
+  default_email=${GIT_DEPLOY_EMAIL:-}
+
+  #repository to deploy to. must be readable and writable.
+  repo=origin
+
+  #append commit hash to the end of message by default
+  append_hash=${GIT_DEPLOY_APPEND_HASH:-true}
+}
+
+main() {
+  parse_args "$@"
+
+  enable_expanded_output
+
+  if ! git diff --exit-code --quiet --cached; then
+    echo Aborting due to uncommitted changes in the index >&2
+    return 1
+  fi
+
+  commit_title=`git log -n 1 --format="%s" HEAD`
+  commit_hash=` git log -n 1 --format="%H" HEAD`
+  
+  #default commit message uses last title if a custom one is not supplied
+  if [[ -z $commit_message ]]; then
+    commit_message="publish: $commit_title"
+  fi
+  
+  #append hash to commit message unless no hash flag was found
+  if [ $append_hash = true ]; then
+    commit_message="$commit_message"$'\n\n'"generated from commit $commit_hash"
+  fi
+    
+  previous_branch=`git rev-parse --abbrev-ref HEAD`
+
+  if [ ! -d "$deploy_directory" ]; then
+    echo "Deploy directory '$deploy_directory' does not exist. Aborting." >&2
+    return 1
+  fi
+  
+  # must use short form of flag in ls for compatibility with OS X and BSD
+  if [[ -z `ls -A "$deploy_directory" 2> /dev/null` && -z $allow_empty ]]; then
+    echo "Deploy directory '$deploy_directory' is empty. Aborting. If you're sure you want to deploy an empty tree, use the --allow-empty / -e flag." >&2
+    return 1
+  fi
+
+  if git ls-remote --exit-code $repo "refs/heads/$deploy_branch" ; then
+    # deploy_branch exists in $repo; make sure we have the latest version
+    
+    disable_expanded_output
+    git fetch --force $repo $deploy_branch:$deploy_branch
+    enable_expanded_output
+  fi
+
+  # check if deploy_branch exists locally
+  if git show-ref --verify --quiet "refs/heads/$deploy_branch"
+  then incremental_deploy
+  else initial_deploy
+  fi
+
+  restore_head
+}
+
+initial_deploy() {
+  git --work-tree "$deploy_directory" checkout --orphan $deploy_branch
+  git --work-tree "$deploy_directory" add --all
+  commit+push
+}
+
+incremental_deploy() {
+  #make deploy_branch the current branch
+  git symbolic-ref HEAD refs/heads/$deploy_branch
+  #put the previously committed contents of deploy_branch into the index
+  git --work-tree "$deploy_directory" reset --mixed --quiet
+  git --work-tree "$deploy_directory" add --all
+
+  set +o errexit
+  diff=$(git --work-tree "$deploy_directory" diff --exit-code --quiet HEAD --)$?
+  set -o errexit
+  case $diff in
+    0) echo No changes to files in $deploy_directory. Skipping commit.;;
+    1) commit+push;;
+    *)
+      echo git diff exited with code $diff. Aborting. Staying on branch $deploy_branch so you can debug. To switch back to master, use: git symbolic-ref HEAD refs/heads/master && git reset --mixed >&2
+      return $diff
+      ;;
+  esac
+}
+
+commit+push() {
+  set_user_id
+  git --work-tree "$deploy_directory" commit -m "$commit_message"
+
+  disable_expanded_output
+  #--quiet is important here to avoid outputting the repo URL, which may contain a secret token
+  git push --quiet $repo $deploy_branch
+  enable_expanded_output
+}
+
+#echo expanded commands as they are executed (for debugging)
+enable_expanded_output() {
+  if [ $verbose ]; then
+    set -o xtrace
+    set +o verbose
+  fi
+}
+
+#this is used to avoid outputting the repo URL, which may contain a secret token
+disable_expanded_output() {
+  if [ $verbose ]; then
+    set +o xtrace
+    set -o verbose
+  fi
+}
+
+set_user_id() {
+  if [[ -z `git config user.name` ]]; then
+    git config user.name "$default_username"
+  fi
+  if [[ -z `git config user.email` ]]; then
+    git config user.email "$default_email"
+  fi
+}
+
+restore_head() {
+  if [[ $previous_branch = "HEAD" ]]; then
+    #we weren't on any branch before, so just set HEAD back to the commit it was on
+    git update-ref --no-deref HEAD $commit_hash $deploy_branch
+  else
+    git symbolic-ref HEAD refs/heads/$previous_branch
+  fi
+  
+  git reset --mixed
+}
+
+filter() {
+  sed -e "s|$repo|\$repo|g"
+}
+
+sanitize() {
+  "$@" 2> >(filter 1>&2) | filter
+}
+
+[[ $1 = --source-only ]] || main "$@"
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