How to Install and Configure Samba in Ubuntu 16.04

1. Install Samba

     sudo apt-get update
     sudo apt-get install samba
   

2. Set a password for your user in Samba

     sudo smbpasswd -a <user_name>
   

   Note: Samba uses a separate set of passwords than the standard Linux system accounts (stored in /etc/samba/smbpasswd). Having said that, I always use here whatever username I use for my Linux account.
3. Create a directory to be shared

     
   mkdir /home/<user_name>/<folder_name>
   

4. Edit the file "/etc/samba/smb.conf"

     
     sudo vim /etc/samba/smb.conf
   

   And add the following:

     
   [global]
     workgroup = HOME_NETWORK
   
   #(Set this to the name you want the shared folder to have)
   [share]
      comment = File server share folder
      path = /home/<user_name>/share/
      browsable = yes
      read only = no
      guest ok = yes
      writable = yes
      valid users = <samba_user_name>
      create mask = 0755
   

5. If you setup a firewall, allow port 445

     ufw allow 445
   

6. Restart the samba:

       sudo service smbd restart
   

7. Once Samba has restarted, use this command to check your smb.conf for any syntax errors

       testparm  
   

Install Latest MySQL in Ubuntu Server

This assumes that you already have a running Ubuntu server with Apache installed. To install basic security in Ubuntu, see Basic Security Installs for Ubuntu. This instructions was extracted from here.

1. Update the package index on your server

sudo apt-get update

2. Install the package

sudo apt-get install mysql-server 

3. Run the included security script. This changes some of the less secure default options for things like remote root logins and sample users.

sudo mysql_secure_installation

4. If you're using a version of MySQL earlier than 5.7.6, you should initialize the data directory by running command below.

sudo mysql_install_db

How to Debug Rails Application Using Pry Remote

1. Add pry remote in gemfile

gem 'pry-remote', '~> 0.1.8' 

gem 'pry-nav', '~> 0.2.4' 

2. Run bundle install in the terminal 

3. Add the following line in application.rb:

require 'pry-remote'

 

 

4. Add the following in the code where you want to stop executing and debug:

binding.remote_pry

 5. Load the application in the browser. The application will stop execution once it encounters the binding.remote_pry line

6. Open up a new terminal and run the following code:

pry-remote

7. To navigate in the terminal, use the following command:

step
next
continue
exit

 

Deploying Rails Application for the First Time

I always forget these steps when deploying a Rails app for the first time. So I'm finally writing this in as a guide for the future.

This assumes that you already have a running Ubuntu server with Apache and Passenger installed (see Basic Security Installs for Ubuntu and How to Install Passenger + Apache in Ubuntu).

1. Clone the git repo.

   git clone git@bitbucket.org:kabalweg/app_name.git
   cd app_name
   bundle install
   

   If you get a "bundle not yet installed" error, run the following comment:

   gem install bundle
   

2. Go to /var/www/ type and this command to create a symbolic link.

   sudo ln -s /home/kabalweg/app_name/ ./app_name
   

3. Go to /etc/apache2/sites-available and create a virtualhost file, app_name.conf, or copy and existing one and edit the appropriate values in that file and save.

   <VirtualHost *:80>
       ServerName app_name.net
       Redirect permanent / http://www.app_name.net/
   </VirtualHost>
   
   <VirtualHost *:80>
     ServerName www.app_name.net
     ServerAdmin kabalweg@gmail.com
   
     # Set the environment to production
     RailsEnv production
   
     <IfModule mod_passenger.c>
         # Set to on when debugging errors
         PassengerFriendlyErrorPages off
   
         #PassengerRoot /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini
         #PassengerDefaultRuby /home/kabalweg/.rvm/gems/ruby-2.2.1@rails4.2/wrappers/ruby
         PassengerMaxPoolSize 2
         PassengerPoolIdleTime 0
         PassengerMaxRequests 1000
       </IfModule>
   
       DocumentRoot /var/www/app_name/public
       <Directory /var/www/app_name/public>
         AllowOverride all
         Options -MultiViews
         #Require all granted
         Order deny,allow
         Allow from all
       </Directory>
   
       ErrorLog ${APACHE_LOG_DIR}/error.log
   
       CustomLog ${APACHE_LOG_DIR}/access.log combined
   </VirtualHost>
   

4. Disable the default virtualhost and enable the new virtualhost file and activate it.

   sudo a2dissite 000-default.conf
   
   sudo a2ensite app_name.conf
   sudo apachectl -k graceful
   

5. Generate secret key and put the resulting key in the secret.yml file.

   rake secret RAILS_ENV=production
   

   Note: It's not a good and safe practice to put production config values in the repo. A good way is to ignore config files (*.yml) using git so it don't get save in the repo, then just manually create this files, with the correct values, in the production server.
6. Pre-compile assets.

   rake assets:precompile RAILS_ENV=production
   

7. Restart application by typing below in your application's root directory.

   touch tmp/restart.txt
   

   Create this folder (tmp) if you don't have this.

How to Install Passenger + Apache in Ubuntu 16.04 LTS

Note: This assumes that you already have a running Ubuntu server. To install basic security in Ubuntu, see Basic Security Installs for Ubuntu. This instructions was extracted from here.

1. Install Apache Server

     sudo apt-get update
     sudo apt-get install apache2
     

2. Set Global ServerName to Suppress Syntax Warnings: "AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message"

     sudo vim /etc/apache2/apache2.conf
     

   and enter at the end of the file:

     ServerName server_domain_or_IP
     

3. Test config so far

     sudo apache2ctl configtest
     

4. Restart Apache for the changes to take effect

     sudo systemctl restart apache2
     

5. Install Passenger packages.

   # Install our PGP key and add HTTPS support for APT
   sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 561F9B9CAC40B2F7
   sudo apt-get install -y apt-transport-https ca-certificates
   
   # Add our APT repository
   sudo sh -c 'echo deb https://oss-binaries.phusionpassenger.com/apt/passenger xenial main > /etc/apt/sources.list.d/passenger.list'
   sudo apt-get update
   
   # Install Passenger + Apache module
   sudo apt-get install -y libapache2-mod-passenger
   

   These commands will install Passenger + Apache module through Phusion's APT repository.
6. Enable the Passenger Apache module and restart Apache

   sudo a2enmod passenger
   sudo apache2ctl restart
   

7. Check installation

   sudo passenger-config validate-install
   

   All checks should pass. If any of the checks do not pass, please follow the suggestions on screen.
8. Check whether Apache has started the Passenger core processes by running the following:

   sudo passenger-memory-stats
   

Creating a Skeleton Rails Application without Database and Test Unit

1. 1. Create application without database access and test unit

       $ rails new [app_name] --skip-active-record --skip-test-unit
   

2. Include Bootstrap
   • Download Bootstrap and extract content
   • Copy bootstrap.min.css and bootstrap.css to /app/assets/css folder
   • Copy bootstrap.min.js and bootstrap.js to /app/assets/js folder
   • Copy fonts folder to /app/assets folder
   Note: The reason why I put bootstrap.css in the main root of asset folder is so I can create a file (ex: custom.css) that will over ride the Bootstrap.css rules in case I want to.
3. Create main controller that will serve as root file.

    $ rails generate controller main_controller index --no-assets --no-helper

4. Set the root route to main_controller#index

       root 'main_controller#index'
   

Basic Security Installs for Ubuntu

The original idea of this post was taken from My First 5 Minutes On A Server; Or, Essential Security for Linux Servers. As I build my server, I follow it but some of it's recommendation does not fit my requirements (ex: connecting via SSH only on certains IPs, which locked me out on several occasions). This post is my own "concoction". This assumes that you already have a fresh server running with only root as user.

1. Login as root and set root password

   passwd
   

   It's always good to use a strong root password. I recommend Random Password Generator for this.
2. Update Ubuntu

   apt-get update
   apt-get upgrade
   

3. Install Fail2ban

   apt-get install fail2ban
   

   Fail2ban is a daemon that monitors login attempts to a server and blocks suspicious activity as it occurs. It’s well configured out of the box.
4. Create user and set-up user folders

   useradd deploy
   mkdir /home/deploy
   mkdir /home/deploy/.ssh
   chmod 700 /home/deploy/.ssh
   

5. Change deploy user's login shell with the 'chsh' command. This will make sure that deploy user will have a more interactive shell.

   sudo chsh -s /bin/bash deploy
   

6. Require public key authentication for logging in

   vim /home/deploy/.ssh/authorized_keys
   

   Copy and paste the contents of the id_rsa.pub on your local machine and any other public keys that you want to have access to this server to the /home/deploy/.ssh/authorized_keys file. Save and close the file.
7. Lock down authorized_keys file and change owner of user folder

   chmod 400 /home/deploy/.ssh/authorized_keys
   chown deploy:deploy /home/deploy -R
   

8. Test the new user (deploy) in a new terminal window

   ssh deploy@<IP_OF_DROPLET>
   

9. While connected as deploy, generate SSH key. This will be used when connecting to github or bitbucket

   ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
   

10. Logout user (deploy), close the the terminal and go back to the terminal where you are logged as root.

    exit
    

11. Change deploy user password. This password will be used when doing sudo commands

    passwd deploy
    

12. Change default text editor to your preference (I like Vim)

    update-alternatives --config editor
    

13. Comment all existing user/group grant lines

    visudo
    

    Add the following line:

    root    ALL=(ALL:ALL) ALL
    deploy  ALL=(ALL:ALL) ALL
    

    This will grant sudo access to the deploy user when they enter the proper password.
14. Set up a firewall to further secure the server using ufw.

    ufw allow 22
    ufw allow 80
    ufw allow 443
    ufw enable
    

15. Enable automatic security updates

    apt-get install unattended-upgrades
    
    vim /etc/apt/apt.conf.d/10periodic
    

    Update the file to look like this:

    APT::Periodic::Update-Package-Lists "1";
    APT::Periodic::Download-Upgradeable-Packages "1";
    APT::Periodic::AutocleanInterval "7";
    APT::Periodic::Unattended-Upgrade "1";
    

    One more config file to edit:

    vim /etc/apt/apt.conf.d/50unattended-upgrades
    

    Update the file to look like below. This will enable security updates only:

    Unattended-Upgrade::Allowed-Origins {
            "Ubuntu lucid-security";
    //      "Ubuntu lucid-updates";
    };
    

    or

    Unattended-Upgrade::Allowed-Origins {
            "${distro_id}:${distro_codename}";
            "${distro_id}:${distro_codename}-security";
    //      "${distro_id}:${distro_codename}-updates";
    //      "${distro_id}:${distro_codename}-proposed";
    //      "${distro_id}:${distro_codename}-backports";
    };
    

16. Restart server and you're done!

    reboot
    

Compare Between Branches in Github

Before you deploy or when you make a release note, typically you would compare master with develop branch to get the differences and find out what has changed. In Github, it's so easy to do that. All you have to do it is go to the following link and supply the branches that you want to compare

https://github.com/kabalweg/my_app/compare/[OUTDATED_BRANCH]...[UPDATED_BRANCH]

Example:

https://github.com/kabalweg/my_app/compare/master...develop

You can also compare between release tags, like so:

https://github.com/kabalweg/my_app/compare/[PREVIOUS_TAG]...[NEW_TAG]

Example:

https://github.com/kabalweg/my_app/compare/2015-05-28...2015-05-29

git: Delete All Local Branches that Already Merged to Master

After sometime using git and creating branches for every feature or bug, you will end up with a lot of branches. Some has been merged to the master branch and some are not. For those that been merged to master, there is no point for them to be in your local machine, so it's better to delete those so it will not clatter your local repository. To do that you just run the command below in your local repo:

git branch --merged | grep -vE "\*|\develop|\master" | xargs -n 1 git branch -d

This command will delete all local branches that are merged to master except for the current checked out branch, develop and master.

Easily Prepare master Branch for Deployment

1) Create a bash script named "prepare_for_deployment" in the root folder of your project and put the git command below:

    release_date=$(date +'%Y-%m-%d')
    git checkout master
    git fetch
    git reset --hard origin/master
    git merge origin/develop
    git push origin master
    git tag $release_date -m "$release_date"
    git push --tags origin $release_date

    

    

2) Make the file executable

    

    $ chmod u+x prepare_for_deployment

    

3) To run the script:

    $ ./prepare_for_deployment

    

NOTE: You can add the path to the script in your $PATH so you don't have to type "./" before the name.

How Make Symbolic Link in Linux/Unix

Every now and then I find myself creating more symbolic link especially when deploying application to production, and I always forget (more like in doubt) the order of parameter when issuing a ln command. I always search for it in google and have to visit more than a couple site to find a example. So, to save time, here is it.

To create a soft link (most common form), use this command:

$ ln -s source destination

Where:

- source = the file or directory you want to link to

- destination = the name of the link that points to the source

Ex:

$ ln -s /home/kabalweg/my_app /var/www/my_app

Better Way to Generate Rails Application

Generate project with RMV.

$ mkdir myapp                                                           # create the project folder

$ cd myapp

$ rvm use ruby-2.1.1@myapp --ruby-version --create     # create a new project-specific gemset

                                                                                 # option “—ruby-version” creates .ruby-version and .ruby-gemset files in the root directory

$ gem install rails --pre                                                # installs the most recent release of Rails 

$ rails new .                                                               # generate application in the current directory.

Click here is you want to create an app without database and test-unit

If you have no RVM in your system, follow command below.  

$ \curl -L https://get.rvm.io | bash -s stable --ruby        # install rvm and ruby

$ rvm get stable --autolibs=enable                              # if you have rvm already, update it

$ rvm install ruby                                                      # install Ruby

$ rvm --default use ruby-2.1.1                                    # use and set it as default

$ gem update --system                                             # update gem

From http://railsapps.github.io/installrubyonrails-mac.html

Backup/Restore MySQL Database

Backup mysql database to a sql file.

$ mysqldump -u root -p[root_password] [database_name] > filename.sql

Restore from sql file to database.

$ mysql -u root -p[root_password] [database_name] < filename.sql

Using scp (Secure Copy) to Copy Files from Remote Server

Copy a file from a remote host to a local machine

$ scp username@example.com:/home/kabalweg/my_archive.ta.gz /home/kabalweg/local

Copy a file from a local machine to a remote host

$ scp /home/kabalweg/local/my_archive.tar.gz username@example.com:/home/kabalweg

 

Compress/Uncompress in Linux/Unix

Compress the folder named sites inside the /home/kabalweg directory:

$ tar -zcvf my_archive.tar.gz /home/kabalweg/sites

Uncompress file into the current directory:

$ tar -zxvf my_archive.tar.gz

Where: 

z = compress archive using gzip program

c = create archive 

v = verbose i.e display progress while creating archive
f = archive File name 

x = extract files

Watching Log Files Using tail and less

Watch the error log and filter the output to the screen (using grep).

tail -f /var/log/apache/error.log | grep -v Exception | grep -v 'PHP Notice'

Output the error log to the screen, filter it before doing so (using grep).

less +F /var/log/apache/error.log | grep -v Exception | grep -v 'PHP Notice'

Note:

-v parameter in grep is reverse look up. It mean, all text except 'Exception' and 'PHP Notice'

Forward and Backward Search in less

/ – search for a pattern which will take you to the next occurrence. 

? – search for a pattern which will take you to the previous occurrence. 

n – for next match in backward direction 

N – for previous match in forward direction

Shift F - similar to tail -f

How to Create User in Mysql

Create the user that can access mysql via localhost:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

If you want the user to access the database from anywhere, then use this:

CREATE USER 'username'@'%' IDENTIFIED BY 'password';

Give the new user permission to access all databases and all its tables:

GRANT ALL PRIVILEGES ON * . * TO 'username'@'localhost';

Reload the privileges:

FLUSH PRIVILEGES;

Git: Merge Develop Branch to Master

Normally when developing, you would make your changes in develop branch and when releasing, merge develop to master branch. Here's the best way to do it:

$ git checkout master                 # make sure you are in master branch
$ git fetch                                  # download commit from remote branch
$ git reset --hard origin/master     # removes changes/commits in local master branch (if any)
$ git merge origin/develop           # merge remote develop to master (the current branch)
$ git push origin master              # push the changes to remote repo

Git: Delete All Local Branches That Were Already Merged to Master

In Git, to clean up your local repository of already merged branches to master (aka pruning), run this command:

$  git checkout master
$  git branch --merged master | grep -v "\* master" | xargs -n 1 git branch -d

This is three commands in one, made possible via pipes ("|").

1) git branch --merged master     # list all the branches that have been merged to master

2) grep -v "\* master"                 # select all the branches that does not match "* master"

3) xargs -n 1 git branch -d          # execute git branch -d with 1 parameter - the branches that was returned by #2

Fix Repeating Content in Email using Handlebars Template

Recently, I reformat our email template and ran into an issue wherein the middle part of the email body is re-populating at the end of the body resulting in duplicate content. The email template was created using Handlebars. My suspect is the character encoding of the production mysql database. But what ever I do (copy the prod DB locally with same encoding, etc), I could not replicate it in my local machine.

Removing the non-printable characters before rendering the content with template fixed it. Here's how I did it.

$cleaned_text = preg_replace('/[\x00-\x1F\x80-\xFF]/', ' ', $text_with_non_printable_chars);

/[\x00-\x1F\x80-\xFF]/ are characters from 0-31, 128-255 in ASCII character code.