An FSND Linux server configuration project

This readme is a tutorial on how to create an instance of a WSGI Apache server with DigitalOcean and host a Python app.

The catalog's built with PostgreSQL & Flask;

• Utilizes mod_wsgi
• SQLAlchemy to connect Python with PSQL;
• Jinja as templating engine
• OAuth2 as user authentication/registration
• Has it's own API

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First, I needed to be certain the app would run with PostgreSQL.

The adjustments needed to be made weren't that large:

1. Change all 'NVARCHAR' columns in dbmodels.py to 'Text'

2. Make sure all paths are absolute and configured for a Linux OS

3. Make sure the items table's foreign keys reference unique columns

   • Before the shop and manufacturer tables had a foreign key on their 'id' column, now the foreign key for manufacturer is 'name'

   This means that when specifying a manufacturer when creating an item, you type their name.

4. Another change to be made was setting up a Postgres user and database, both named catalog, to enable testing of the app

   • When the database and user had been made, the last step was:

5. Changing create_engine() in catalog.py & dbmodels.py to postgresql://catalog:catalog@localhost/catalog

This was a great time to test everything in the app and make sure nothing was broken. As you'd hope no breaking changes had been made and everything runs smoothly.

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The following guide assumes you are redirecting your DNS provider's name servers to DigitalOcean.

Setting up DNS on DigitaOcean is done as follows:

• Go to the network tab
• Enter the domain
• Declare your favorite DNS records, mine are:
  • A record to gideonservice.me
  • CNAME record to make any prefix redirect to gideonservice.me
  • NS records to DigitalOcean

Setting up a DigitalOcean Server

Go to digitalocean.com and create a droplet with Ubuntu 14.04 and wait for it to deploy.

Configuring authorization

• Open a bash terminal locally
  • On Windows: install git and use git-bash
• Copy the temporary password from the email you received at droplet creation

ssh root@< server IP-address >
< temporary password >
adduser < user >
gpasswd -a < user > sudo
sudo cp /etc/sudoers.d/90-cloud-initusers /etc/sudoers.d/< user >
sudo nano /etc/sudoers.d/< user >

inside the sudoers.d/grader change the word root to < user >

• < user > can run commands with sudo privileges now!

• Locally run ssh-keygen, name the key by saving it to your default .ssh directory

• Locally run cat ~/.ssh/< RSA-key-name >.pub and copy it

On the server as root user

su < user >
cd  /home/< user >
mkdir .ssh
sudo nano .ssh/authorized_keys

(Paste the contents of < rsa-key-name >.pub then save and exit)

sudo chmod 644 .ssh/authorized_keys
sudo chmod 700 .ssh
exit (until current user is root)

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• Run sudo nano /etc/ssh/sshd_config

  • Change the line PermitRootLogin yes to PermitRootLogin no

  • Change the line PasswordAuthentication yes to PasswordAuthentication no

  • Change the line Port 22 to Port 2222

  • Save and exit

• Run sudo service ssh restart

Logging in as < user >

Locally, open bash and run ssh < user >@< server-IP > -p 2222 -i ~/.ssh/< rsa-key-name >

Software installation

Run the following commands:

sudo apt-get -y update
sudo apt-get -y install finger
sudo apt-get -y install python2.7 python-pip
sudo -H pip2 install --upgrade pip
sudo apt-get -y install postgresql postgresql-contrib
sudo apt-get -y install apache2 libapache2-mod-wsgi
sudo apt-get -y install python-dev
sudo apt-get -y install git
sudo apt-get -y update
sudo apt-get -y upgrade
sudo apt-get -y autoremove

To confirm everything is working as it should so far: go to your browser, enter your servers IP-address and see if the default apache page is there. If nothing displays, run above commands again. If you still don't receive anything you should start over.

Setting up PostgreSQL

Securing the connection

Make sure no remote connections are allowed by looking in the host based authentication file:

sudo nano /etc/postgresql/9.3/main/pg_hba.conf

Check if the following text matches the bottom of the file:

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

Anything else in this section of the config file should be deleted.

Create a database with an unauthorized user

sudo su postgres
createuser --interactive -W -P < DB-username > (catalog no no no catalog catalog)
createdb -O < DB-owner > < DB-name >
exit

Whenever you make a change to the configuration of most services in Linux, you will have to restart them for the change to take effect. For now, use these commands:

• sudo service postgresql restart

• sudo service ssh restart

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Download and configure the application

This is assuming apache2 is installed properly.

cd /var/www/
sudo mkdir flaskapps
sudo cd /flaskapps
sudo mkdir catalog
sudo git clone https://github.com/GideonFlynn/Item-Catalog.git
sudo mv /Item-Catalog/* /catalog/

To remove unused files/folders (and the .git folder), run these commands:

cd /var/www/flaskapps/
sudo rm -r -f Item-Catalog/

Setting up a virtual environment for Python

cd var/www/flaskapps/catalog
sudo pip install virtualenv
sudo virtualenv venv
source venv/bin/activate
sudo pip install -r requirements.txt
deactivate

Then we'll enable the app, first run:

sudo a2enmod wsgi
sudo nano /etc/apache2/sites-available/catalog.conf

Then paste the following code into catalog.conf

<VirtualHost *:80>
                ServerName < server-IP >
                ServerAlias < DNS >
                ServerAdmin < admin-email@example.com >
                WSGIScriptAlias / /var/www/flaskapps/catalog.wsgi
                <Directory /var/www/flaskapps/catalog/>
                        Order allow,deny
                </Directory>
                Alias /static /var/www/flaskapps/catalog/static
                <Directory /var/www/flaskapps/catalog/static/>
                        Order allow,deny
                        Allow from all
                </Directory>
                ErrorLog ${APACHE_LOG_DIR}/error.log
                LogLevel warn
                CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

Save and exit

Configuring the WSGI

sudo a2ensite catalog
cd /var/www/flaskapps/
sudo nano catalog.wsgi

Paste the following code into /var/www/flaskapps/catalog.wsgi

#!/usr/bin/python
import sys
import logging
logging.basicConfig(stream=sys.stderr)
sys.path.insert(0,"/var/www/flaskapps/catalog")

from catalog import app as application
application.secret_key = 'Add your secret key'

Save and exit

Run cd /var/www/flaskapps/catalog

We want to make sure the /static/uploads/images folders are present.

If not:

cd /static
sudo mkdir uploads
cd /uploads
sudo mkdir images
cd /var/www/flaskapps/catalog

If/when the folder is present:

cd /var/www/flaskapps/catalog
sudo chmod 777 -R static/
sudo service apache2 restart

Setting up The Uncomplicated Firewall a.k.a ufw

We waited to configure the firewall until now, so we're certain to be able to log in even if something goes wrong.

sudo ufw status
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow 2222/tcp
sudo ufw allow www
sudo ufw allow ntp
sudo ufw enable (press 'y')
sudo ufw status

Now your terminal should display this text:

Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere
2222/tcp                   ALLOW       Anywhere
80/tcp                     ALLOW       Anywhere
123                        ALLOW       Anywhere
22 (v6)                    ALLOW       Anywhere (v6)
2222/tcp (v6)              ALLOW       Anywhere (v6)
80/tcp (v6)                ALLOW       Anywhere (v6)
123 (v6)                   ALLOW       Anywhere (v6)

Configuring the time zone

• Run sudo dpkg-reconfigure tzdata
• Select 'None of these' with your arrow keys
• Select UTC

Reboot!

After initial configuration, it would be a good idea to reboot the system:

• Run sudo apt-get update and sudo apt-get -y dist-upgrade.

• Run reboot

• Login with ssh ssh < user >@< server-IP > -p 2222 -i ~/.ssh/< rsa-file-name >

In your browser, go to the server name/alias you defined in catalog.conf and enjoy!