mongodb deployment using fabric and pymongo

We are going to create a fabric file which will deploy the mongodb to the Internet. To do this, we should have to have an idea about fabric.

Fabric is a Python library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks. It provides a basic suite of operations for executing local or remote shell commands (normally or via sudo) and uploading/downloading files, as well as auxiliary functionality such as prompting the running user for input, or aborting execution.

'''Task-1:''' First, clone the repo and you need to backup the db( or download from s3 then unzip db ) and place it to the repo directory where you cloned. As example, in our case "db-folder" is the backed up directory.

'''Task-2:''' Goto the fabric file and take a look at the dev() function. In this function there are some environment variables which defines the database information.

env.mongo_script = 'runDB.py'
env.db_path = 'db-folder'
env.db_name = 'db-folder'
env.db_user = 'db-folder'
env.db_pwd = 'your db-folder password'

Here in this snippet, the env.mongo_script variable contains a script which will create the database and user with username, password and db-roles. Here is the code:

from pymongo import MongoClient

client = MongoClient('localhost:27017')
db = client.db-folder
coll = db.dataset
db.add_user('db-folder', 'db-password', roles=["readWrite", "dbAdmin"])

The other environment variables like env.db_path, env.db_name, env.db_user and env.db_pwd contains the value of database path (/home/ubuntu/db-folder), name of database, username and password.

'''Task-3:''' In the install() function firstly, the system will be updated then install mongodb using apt sources. In the mongodb_config() function, mongodb systemd file path is specified. If the path exists then it'll remove the file and upload mongodb.service systemd file. Here is the snippet:

def mongodb_config():
   print 'configuring mongodb'
   default_config='/etc/systemd/system/mongodb.service'
   if exists(default_config):
       sudo('rm /etc/systemd/system/mongodb.service')
       print 'Deleted default config'

   print 'Install mongodb config service file'
   put('%s' % (env.mongodb_service_config), '/etc/systemd/system/', use_sudo=True)

The next task of this function is to specify the mongodb configuration file path. It removes the file if exists and upload the local mongod.conf file from the repo directory. Here is the snippet:

def mongodb_config():
  default_config='/etc/mongod.conf'
  if exists(default_config):
    sudo('rm /etc/mongod.conf')
    print 'Deleted default mongo config for login and security'
  print 'Install mongodb config file for security and remote login'
  put('%s' % (env.mongodb_config), '/etc/', use_sudo=True)
  sudo('systemctl daemon-reload')
  sudo('systemctl restart mongodb')
  return

Now, the install_pymongo() function installs pymongo so that the runDB.py can run perfectly on the server. The running_db() function first upload the script to the home directory and run the script. Then restore the database using mongorestore command and enabled the authentication by editing the /etc/mongod.conf file and then restart the mongodb service.

Lastly, the sync_code_base() function upload the database to the server's home directory which is called in the deploy() function.