Scripting Example

restart.sh

#!/bin/bash

#  Usage:
#  $ bin/restart
#  Remember to be on the root of the project.
#  Script does not take any arguments.
#  This script makes most of its decision based on the ENVIRONMENT value in .env.
#  This is important for deploying correct branch as well as starting correct celery worker.

main() {
  echo "Welcome!"
  echo "This script will kill and re-run Flask and Celery Workers."
  echo
  echo "-----------------------------------------------------"

#  Checking if .env exists
  if [ ! -f .env ]; then
    echo "dotenv (.env) file not found. EXITING!"
    exit 1
  fi

  environment="$(awk -F= -v key="ENVIRONMENT" '$1==key {print $2}' .env)"

  if [ -z "$environment" ]; then
    echo "ENVIRONMENT not set in .env"
    exit 1
  fi

  if [[ "$environment" != "staging" && "$environment" != "production" ]]; then
    echo "Invalid ENVIRONMENT setup."
    exit 1
  fi

  confirm_prerequisites "$environment"

  read -p "Do you want to proceed with deployment process? [y/N] " -n 1 -r
  if [[ ! $REPLY =~ ^[Yy]$ ]]
  then
    echo
    echo "You chose not to proceed! Exiting!"
    exit 1
  fi

  update_codes

  flask_string="flask run --host 0.0.0.0"
  celery_string="app.celery_app:app"

  echo "-----------------------------------------------------"
  echo "!!! Kill process initiated !!!"

#  Killing existing processes...
  kill_processes "$flask_string" # Flask
  kill_processes "$celery_string" # Celery Worker

  restart_server "$environment"

  echo
  echo "Script Execution Complete! Bye! Bye!"
}

update_codes() {
  echo; echo;
  echo "-----------------------------------------------------"
  branch=$(git branch --show-current)
  echo "Do you want to pull the code ('git pull origin ${branch}')"
  PS3='Please enter your choice: '
  options=("Pull Codes" "Already Pulled (Continue)" "Manual Pull (Quit)")
  select opt in "${options[@]}"
  do
      case $opt in
          "Pull Codes")
              echo "Pulling codes!"
              git pull origin "$branch"
              break
              ;;
          "Already Pulled (Continue)")
              echo "Assuming you pulled codes manually."
              break
              ;;
          "Manual Pull (Quit)")
              echo "You chose to exit!"
              exit 0
              break
              ;;
          *) echo "Invalid option $REPLY";;
      esac
  done
  echo
}

confirm_prerequisites() {
  echo "IMPORTANT: Make sure of following things: "
  echo "1. Codes are updated."
  echo "2. You are in correct branch."
  echo "3. You have activated correct virtualenv."
  echo "4. You are inside the Project's root directory."
  echo "-----------------------------------------------------"
  echo

  git_branch=$(git branch --show-current)
  invalid_branch=false
  virtualenv_inactive=false
  if [[ $1 == "staging" && $git_branch != "master" || $1 == "production" && $git_branch != "production" ]]; then
    invalid_branch=true
  fi
  if [ -z "$VIRTUAL_ENV" ]; then
    virtualenv_inactive=true
  fi

  echo "Current Environment:"
  echo "Environment            :${1}"
  echo "Git branch             :${git_branch}"
  echo "Python Virtual ENV     :$VIRTUAL_ENV"
  echo "-----------------------------------------------------"

  errors="ERRORS!!!"

  if [ $invalid_branch = true ]; then
    errors="${errors}
    ⚠ Seems like the environment does not match with current git branch!
        Correct combination is: [staging & master] | [production & production]."
  fi

  if [ $virtualenv_inactive = true ]; then
    errors="${errors}
    ⚠ Seems like the Virtual Environment has not been activated.
        Activate the respective python virtual environment."
  fi

  if [[ $invalid_branch = true || $virtualenv_inactive = true ]]; then
    echo
    echo "⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠"
    echo "$errors"
    echo "⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠"
    echo
    echo "Some prerequisites did not meet! EXITING!"
    exit 1
  fi


}

kill_processes() {
  search_string=$1
  echo "Killing: ${search_string}"
  process_ids=($(ps -ef | grep "${search_string}" | grep -v "grep" | awk '{print $2}'))
  echo $process_ids
  for pid in "${process_ids[@]}"
  do
    kill -9 "$pid"
    echo "Process (${pid}) Killed!"
  done
  echo "Killing Complete!"
  echo "-----------------------------------------------------"
}

restart_server() {
  echo
  echo "Restart the Server!"
  read -p "Do you want to restart the server and celery? [y/N] " -n 1 -r
  echo
  if [[ $REPLY =~ ^[Yy]$ ]]
  then
    echo "Starting: Server"
    echo "nohup flask run --host 0.0.0.0 &"
    nohup flask run --host 0.0.0.0 &
    echo "---------------------------------"

    echo "Starting: Celery Worker"
    echo "nohup celery -A app.celery_app:app worker -n $USER-$1-worker --queues=default --pool=gevent --loglevel=INFO --concurrency=1 --max-tasks-per-child=1 > default.out 2> default.err &"
    nohup celery -A app.celery_app:app worker -n "$USER-$1-worker" --queues=default --pool=gevent --loglevel=INFO --concurrency=1 --max-tasks-per-child=1 > default.out 2> default.err &

    echo "---------------------------------"
  fi

}

main