Jurager/Deployer

This bash script provides a straightforward method for achieving zero-downtime deployment with various NodeJS frameworks, and it can also automate the deployment process for other types of applications.

Requirements

For reading deploy.config.json configuration, additional packages is required.

To install Ubuntu/Debian

sudo apt-get install jq

To install on Fedora/CentOS

sudo dnf install jq

Installation

Download deployer.sh, move it in your project directory (see usage), or install globally by moving to /usr/local/bin

Usage

In this example we have application written over NuxtJS, serve it using Nginx.

We want to implement green/blue (zero-downtime) deployment on this application.

Note

We use two applications at once. At the time of deployment, we build the application which is not running. When all deployment task is done, one application is stopped another is starting. At this moment Nginx switches to another upstream, transparently to user.

First, define the upstream in Nginx with sample configuration

upstream backend {
    server 127.0.0.1:3000 fail_timeout=0;
    server 127.0.0.1:3001 fail_timeout=0;
}

Then, in server directive, change the location as follows

location / {
    proxy_pass                          http://backend; # set the address of the Node.js instance here
    proxy_next_upstream error timeout   invalid_header http_500;
    proxy_connect_timeout               2;
    proxy_set_header Host               $host;
    proxy_set_header X-Real-IP          $remote_addr;
    proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
    proxy_redirect                      off;
    proxy_buffering off;
}

Application is running in daemon mode using supervisord with two configurations as follows

example.blue.conf

[program:myapp-blue]
directory=/home/myapp/blue/
command=/bin/bash -c 'nuxt start'
user=myapp
autostart=true
autorestart=true
redirect_stderr=true
stdout_logfile=/var/log/supervisor/myapp-blue.log

example.green.conf

[program:myapp-green]
directory=/home/myapp/green/
command=/bin/bash -c 'nuxt start'
user=myapp
autostart=true
autorestart=true
redirect_stderr=true
stdout_logfile=/var/log/supervisor/myapp-green.log

Structure of application will be following:

/home/
    /myapp/
        /green/
            myapp.js
        /blue
            myapp.js
        deploy.config.json

Configuration deploy.config.json must be in directory near green and blue

{
  "current":"green",
  "commands":{
    "prepare":[
      "git pull"
    ],
    "install":[
      "npm i"
    ],
    "build":[
      "npm run build"
    ],
    "restart":[
      "supervisorctl start merchant-#NEXT_COLOR#",
      "supervisorctl stop merchant-#CURRENT_COLOR#"
    ]
  },
  "logging":{
    "enabled":true,
    "file":"deploy.log"
  }
}

To list all available commands, use

deployer.sh -h
Tool used to implement zero downtime deployment.

Syntax: deployer.sh [-i|v|c|h]
Options:
c  Echo current color.
i  Run commands from 'commands.install' group immediately after prepare
v  Print version.

To run the deployment process, run following command in directory with configuration, and wait for process to complete

cd /home/myapp && deployer.sh

License

This package is open-sourced software licensed under the MIT license.