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rails_locdev.html
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<!DOCTYPE html>
<html lang="en">
<head>
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<meta name="author" content="How to master your Ruby on Rails development environment">
<title>Rails local development environment</title>
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<body class="article toc2 toc-left">
<div id="header">
<h1>Rails local development environment</h1>
<div class="details">
<span id="author" class="author">How to master your Ruby on Rails development environment</span><br>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_ubuntu_rvm_and_postgresql">Ubuntu, rvm and PostgreSQL</a>
<ul class="sectlevel2">
<li><a href="#_ubuntu">UBUNTU</a></li>
<li><a href="#_login_shell">Login shell</a></li>
<li><a href="#_rvm">RVM</a></li>
<li><a href="#_postgresql">PostgreSQL</a></li>
<li><a href="#_redis">Redis</a></li>
<li><a href="#_atom">Atom</a></li>
<li><a href="#_git_aware_prompt">Git aware prompt</a></li>
<li><a href="#_create_a_new_ruby_on_rails_application">Create a new Ruby on Rails application</a></li>
<li><a href="#_cloning_an_existing_repository_and_start_working">Cloning an existing repository and start working</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p>To those interested in learning Ruby on Rails I strongly recommend Michael Hartl’s <a href="https://www.railstutorial.org/">Ruby on Rails Tutorial</a>, first of all because it is the best tutorial on Ruby on Rails you can find in Internet, and secondly because it is the best tutorial on Ruby on Rails.</p>
</div>
<div class="paragraph">
<p>Moreover this documentation is largely based upon it, requires in fact the intention to follow that tutorial and from some point onwards requires its completion.</p>
</div>
<div class="paragraph">
<p>In the first part of this documentation, called "<em>Rails local development environment</em>", I decided to share instructions on how to switch from a cloud development environment like Cloud9, suggested in the aforementioned tutorial, to a local development environment, that is your own computer. The advantages in this changes are many. First of all your computer does not have the limitations that Cloud9 has, so you will not encounter warnings like "This Environment is Running Low on Memory" or "This Environment Has High CPU Load". Also, Cloud9 has space limit, so there are limitations in the number of projects that it will be capable of hosting. Using your own computer as development environment you will not need to think of upgrading to a payed plan. Last but not least consider that Cloud9 is part of Amazon AWS since July 2016. As you can read <a href="https://en.wikipedia.org/wiki/Cloud9_IDE">on Wikipedia</a>, "On April 2 2019, Cloud9 announced that users would not be able to create new and use old workspaces on c9.io (aka original version, not Amazon Cloud9) after June 30, 2019". In fact, that is exactly what happened to me: after June 2019 I was no more able to use my old workspaces, they were gone, vanished. Switching to my computer as IDE was a matter of necessity. Using your computer as IDE may spare you from bad experiences like mine.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ubuntu_rvm_and_postgresql"><a class="anchor" href="#_ubuntu_rvm_and_postgresql"></a>Ubuntu, rvm and PostgreSQL</h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_ubuntu"><a class="anchor" href="#_ubuntu"></a>UBUNTU</h3>
<div class="paragraph">
<p>This documentation requires Ubuntu as operative system.</p>
</div>
</div>
<div class="sect2">
<h3 id="_login_shell"><a class="anchor" href="#_login_shell"></a>Login shell</h3>
<div class="paragraph">
<p>Using RVM without properly configuring your terminal emulator, you may encounter the following issue:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm use 2.0.0
RVM is not a function, selecting rubies with 'rvm use ...' will not work.
You need to change your terminal emulator preferences to allow login shell.
Sometimes it is required to use `/bin/bash --login` as the command.
Please visit https://rvm.io/integration/gnome-terminal/ for a example.</code></pre>
</div>
</div>
<div class="paragraph">
<p>In order to be able to run RVM as a function it is necessary to run your console as login shell. Open your Ubuntu terminal and ago to Edit > Preferences > Command. Then check 'Run command as a login shell'. See <a href="https://unix.stackexchange.com/a/46856/184919">at StackExchange</a> the differences between a login shell and a non-logging shell.</p>
</div>
</div>
<div class="sect2">
<h3 id="_rvm"><a class="anchor" href="#_rvm"></a>RVM</h3>
<div class="paragraph">
<p>In the course of your career as developer you will find the necessity to use different versions of Ruby. You may start to create an application with a certain Ruby version, then realize, when it is completed, that in meantime Ruby was upgraded, so the new version is available for your next projects. Every project requires a certain amount of time for its completion and during that time Ruby, be certain, will be upgraded. This is why it is necessary to switch from a Ruby version to another one every time you switch from and to different applications. In fact, bear in mind that, as it is written in Chapter 7 of the Ruby on Rails Tutorial, "<em>should you ever end up running a mission-critical app…​ specifying an exact Ruby version in the Gemfile is recommended to ensure maximum compatibility between development and production environments</em>".</p>
</div>
<div class="paragraph">
<p>There are different version managers. The most used are RVM and rbenv. This documentation is about <a href="https://rvm.io/">RVM</a>.</p>
</div>
<div class="paragraph">
<p>RVM has a dedicated <a href="https://github.com/rvm/ubuntu_rvm">Ubuntu package</a>, as written in the <a href="https://rvm.io/rvm/install#ubuntu">RVM documentation</a>.</p>
</div>
<div class="paragraph">
<p>A fundamental idea grounded in RVM is the opportunity to work with different gemsets. A gemset is a collection of Ruby gems necessary for the working of an application. So, if you have different applications, you will also end up with different gemsets. This is so useful because every application will be developed in a closed environment, with all its required Ruby gems, included Rails. So, if you have two application, say Fireworks and Watergames, each of these application will have its own collection of Ruby gems because they are different applications that require different Ruby gems.</p>
</div>
<div class="paragraph">
<p>You need <strong>software-properties-common</strong> installed in order to add PPA repositories.
Check if it is installed:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ dpkg -l software-properties-common</code></pre>
</div>
</div>
<div class="paragraph">
<p>If not installed, open a terminal and run:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo apt install software-properties-common</code></pre>
</div>
</div>
<div class="paragraph">
<p>Add the PPA and install the package:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo apt-add-repository -y ppa:rael-gc/rvm
$ sudo apt update
$ sudo apt install rvm</code></pre>
</div>
</div>
<div class="paragraph">
<p>Now, in order to always load rvm, change the Gnome Terminal as follows:</p>
</div>
<div class="paragraph">
<p>At terminal window, click Edit > Preferences > Command and check "<em>Run command as login shell</em>".<br>
Reboot your system.</p>
</div>
<div class="paragraph">
<p>Now you’re ready to install rubies. Open a terminal and run:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm install 2.7.1</code></pre>
</div>
</div>
<div class="paragraph">
<p>This will install Ruby version 2.7.1<br>
If you want to install another version of Ruby, replace "2.7.1" with your chosen version of Ruby.</p>
</div>
<div class="paragraph">
<p>To see all installed Ruby environments, run the following command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm list</code></pre>
</div>
</div>
<div class="paragraph">
<p>The output of the "rvm list" command will be like the following:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs"> * ruby-2.5.1 [ x86_64 ]
=> ruby-2.7.1 [ x86_64 ]
# => - current
# =* - current && default
# * - default</code></pre>
</div>
</div>
<div class="paragraph">
<p>The above output says that in the system there are <code>Ruby 2.5.1</code> and <code>Ruby 2.7.1</code>.<br>
<code>Ruby 2.5.1</code> is the default Ruby interpreter while <code>Ruby 2.7.1</code> is the current Ruby interpreter.</p>
</div>
<div class="paragraph">
<p>To use a particular Ruby version:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm use 2.7.1</code></pre>
</div>
</div>
<div class="paragraph">
<p>Since you installed only Ruby 2.7.1 the output of the "rvm list" command will be:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">=* ruby-2.7.1 [ x86_64 ]
# => - current
# =* - current && default
# * - default</code></pre>
</div>
</div>
<div class="paragraph">
<p>Check what Ruby gemsets are installed in your system:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm gemset list</code></pre>
</div>
</div>
<div class="paragraph">
<p>The output will be as follows:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">gemsets for ruby-2.7.1 (found in /home/knzudgt/.rvm/gems/ruby-2.7.1)
=> (default)
global</code></pre>
</div>
</div>
<div class="paragraph">
<p>When you install a ruby, two gemsets will be created, the global gemset and the default gemset. As written in the RVM documentation, "the 'global' gemset is to allow you to share gems to all your gemsets. The word 'default' quite literally says it all, eg. the gemset used without selecting one for a specific installed ruby". If you don’t use a gemset at all, you get the gems in the 'default' set. If you use a specific gemset (say @fireworks), it will inherit gems from that ruby’s @global.</p>
</div>
<div class="sect3">
<h4 id="_rvms_global_gemset"><a class="anchor" href="#_rvms_global_gemset"></a>RVM’s Global Gemset</h4>
<div class="paragraph">
<p>To see what gems are installed in the “global” gemset:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ rvm gemset use global
$ gem list</code></pre>
</div>
</div>
<div class="paragraph">
<p>To get a list of gems that are outdated:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ gem outdated</code></pre>
</div>
</div>
<div class="paragraph">
<p>A trouble-free development environment requires the newest versions of the default gems.<br>
To update all stale gems, if any:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ gem update</code></pre>
</div>
</div>
<div class="paragraph">
<p>Check that 'bundler' and 'Nokogiri' are included in the 'global' gemset looking at the output of command 'gem list'. The Bundler gem is an essential tool for managing gems when developing and running Rails applications. Nokogiri is a gem that is a dependency for many other gems. See at <a href="http://railsapps.github.io/installrubyonrails-ubuntu.html">railsapp</a>.</p>
</div>
<div class="paragraph">
<p>Install 'Nokogiri' in the global gemset, so that it is included in every new rails application.
It is possible to install a gem in any gemset. In this case with the previous 'rvm gemset use global' command we entered in the global gemset. With the command below we will install 'nokogiri' in the current, global gemset:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ gem install nokogiri</code></pre>
</div>
</div>
<div class="paragraph">
<p>'bundler' should already be installed in the global gemset. If it is not installed, do it with the following command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ gem install bundler</code></pre>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_postgresql"><a class="anchor" href="#_postgresql"></a>PostgreSQL</h3>
<div class="paragraph">
<p>As it is written in Chapter 3 of the Ruby on Rails Tutorial, "<em>Generally speaking, it’s a good idea for the development and production environments to match as closely as possible, which includes using the same database, so I recommend eventually learning how to install and configure PostgreSQL in development</em>".</p>
</div>
<div class="paragraph">
<p>Since installing and configuring PostgreSQL in Ubuntu is not that difficult, I suggest to do it as soon as possible.</p>
</div>
<div class="paragraph">
<p>PostgreSQL can be installed as package from the Ubuntu repository or installed from the PostgreSQL apt repository. Ubuntu "snapshots" a specific version of PostgreSQL, while the PostgreSQL Apt Repository will provide automatic updates for all supported versions of PostgreSQL throughout the support lifetime of PostgreSQL (<a href="https://www.postgresql.org/download/linux/ubuntu/">See PostgreSQL documentation</a>).</p>
</div>
<div class="paragraph">
<p>This documentation is about installing PostgrSQL as Ubuntu package from the official Ubuntu repository.</p>
</div>
<div class="paragraph">
<p>To install the server locally use the command line and type:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo apt update
$ sudo apt install postgresql postgresql-contrib</code></pre>
</div>
</div>
<div class="paragraph">
<p>This will install the latest version available in your Ubuntu release and the commonly used add-ons for it.<br>
Check if your system has already the package <code>libpq-dev</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ dpkg -l libpq-dev</code></pre>
</div>
</div>
<div class="paragraph">
<p>If it is not installed, install it or you may encounter problems while installing gem 'pg':</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo apt install libpq-dev</code></pre>
</div>
</div>
<div class="paragraph">
<p>See <a href="https://stackoverflow.com/a/6040822/5078888">at Stackoverflow</a>.</p>
</div>
<div class="paragraph">
<p>To check version and path of the freshly installed postgresql run the following commands:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ psql --version
$ which psql</code></pre>
</div>
</div>
<div class="paragraph">
<p>By default, when PostgreSQL is installed, a postgres user is also added, with no set password. It also creates a system account with same name ‘postgres’. Precisely, "<em>by default Postgres uses a concept called “roles” to handle in authentication and authorization. These are, in some ways, similar to regular Unix-style accounts, but Postgres does not distinguish between users and groups and instead prefers the more flexible term “role”</em> " (See <a href="https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-18-04">at Digitalocean</a>). To avoid confusion, we will refer to roles as 'users'.</p>
</div>
<div class="paragraph">
<p>You can check this running the command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ cat /etc/passwd</code></pre>
</div>
</div>
<div class="paragraph">
<p>On most Unix and Linux distributions the default authentication mode is set to 'ident' which means a given Unix user X can only connect as the postgres user X. If a user (role) exists within Postgres, a Unix/Linux username with the same name is able to sign in as that role. (See <a href="https://www.postgresql.org/docs/10/auth-methods.html">PostgreSQL documentation</a>).</p>
</div>
<div class="paragraph">
<p>With the default authentication method "<em>if your Ubuntu username is 'foo' and you add 'foo' as a Postgresql user then you can connect to the database without requiring a password</em>". "<em>Since the only user who can connect to a fresh install is the postgres user, here is how to create yourself a database account (which is in this case also a database superuser) with the same name as your login name</em>":</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo -u postgres createuser --superuser $USER</code></pre>
</div>
</div>
<div class="paragraph">
<p>See: <a href="https://help.ubuntu.com/community/PostgreSQL#Alternative_Server_Setup">help.ubuntu.com</a></p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
It is advisable not to set a password for the newly created postgres user so that this information, written in config/database.yml, will not be sent over the internet. On the other hand, most people add database.yml to their .gitignore file so it stays out of version control.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>To connect to PostgreSQL as $USER we must specify which database we want to connect to:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ psql -d postgres</code></pre>
</div>
</div>
<div class="paragraph">
<p>After log in we could check the list of databases with '\l':</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
(3 rows)</code></pre>
</div>
</div>
<div class="paragraph">
<p>As you can see postgresql creates three databases by default.
Information on template0 and template1 databases can be found <a href="http://www.postgresql.org/docs/current/static/manage-ag-templatedbs.html">in the PostgreSQL documentation</a>.</p>
</div>
<div class="paragraph">
<p>Exit from postgres with \q:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">postgres=# \q</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_redis"><a class="anchor" href="#_redis"></a>Redis</h3>
<div class="paragraph">
<p>This short documentation is part of a broader documentation about Ruby on Rails. If you think that your application will have a considerable amount of traffic, my personal advise is to deploy your application not to Heroku, as suggested by the Ruby on Rails Tutorial, but to a different hosting provider, which offers affordable plans. You should consider that Heroku in fact is expensive as you <a href="https://www.speedshop.co/2015/07/29/scaling-ruby-apps-to-1000-rpm.html">scale</a>. The free plan offers only 1 web and 1 worker dynos. <em>Adding more web dynos allows you to handle more concurrent HTTP requests, and therefore higher volumes of traffic</em> (See <a href="https://devcenter.heroku.com/articles/dynos#scalability">at Heroku</a>). Worker dynos are important too. "<em>Worker dynos can be of any process type declared in your Procfile, other than “web”. Worker dynos are typically used for background jobs, queueing systems, and timed jobs</em>". Especially background processes are a fundamental part of web applications. For instance, a background process allows to delete automatically all outdated microposts, and free space in your drive. <a href="https://github.com/mperham/sidekiq">Sidekiq</a> is a <em>simple, efficient background processing for Ruby. It aims to be simple to integrate with any modern Rails application and much higher performance than other existing solutions. Sidekiq uses Redis to store all of its job and operational data</em>. Since we will use Sidekiq for background processes we will install Redis.</p>
</div>
<div class="paragraph">
<p><a href="https://redis.io/">Redis</a> <em>is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker</em>. Below are the instructions to install Redis in Ubuntu.
Install redis server with the following command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo apt install redis-server</code></pre>
</div>
</div>
<div class="paragraph">
<p>This will download and install Redis and its dependencies.
Once the Redis server installation is finished you can check the Redis server version:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ redis-server -v</code></pre>
</div>
</div>
<div class="paragraph">
<p>Following installation, there is one important configuration change to make in the Redis configuration file, which was generated automatically during the installation.</p>
</div>
<div class="paragraph">
<p>Open this file with your preferred text editor:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo vi /etc/redis/redis.conf</code></pre>
</div>
</div>
<div class="paragraph">
<p><em>Inside the file, find the <code>supervised</code> directive. This directive allows you to declare an init system to manage Redis as a service, providing you with more control over its operation. The <code>supervised</code> directive is set to no by default. Since you are running Ubuntu, which uses the systemd init system, change this to systemd</em>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">...
# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
# supervised no - no supervision interaction
# supervised upstart - signal upstart by putting Redis into SIGSTOP mode
# supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
# supervised auto - detect upstart or systemd method based on
# UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
# They do not enable continuous liveness pings back to your supervisor.
supervised systemd</code></pre>
</div>
</div>
<div class="paragraph">
<p><em>That’s the only change you need to make to the Redis configuration file at this point, so save and close it when you are finished. Then, restart the Redis service to reflect the changes you made to the configuration file</em>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">sudo systemctl restart redis.service</code></pre>
</div>
</div>
<div class="paragraph">
<p><em>With that, you’ve installed and configured Redis and it’s running on your machine</em>. See <a href="https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-18-04">at DigitalOcean</a></p>
</div>
<div class="paragraph">
<p>checking that the Redis service is running:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">sudo systemctl status redis</code></pre>
</div>
</div>
<div class="paragraph">
<p>If it is running without any errors, this command will produce output similar to the following:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">● redis-server.service - Advanced key-value store
Loaded: loaded (/lib/systemd/system/redis-server.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2020-06-09 15:33:02 CEST; 1h 3min ago
Docs: http://redis.io/documentation,
man:redis-server(1)
Process: 1126 ExecStart=/usr/bin/redis-server /etc/redis/redis.conf (code=exited, status=0/SUCCESS)
Main PID: 1154 (redis-server)
Tasks: 4 (limit: 4915)
CGroup: /system.slice/redis-server.service
└─1154 /usr/bin/redis-server 127.0.0.1:6379</code></pre>
</div>
</div>
<div class="paragraph">
<p><em>Here, you can see that Redis is running and is already enabled, meaning that it is set to start up every time the server boots</em>.</p>
</div>
<div class="paragraph">
<p>Type <code>q</code> (quit) to exit from the previous command.</p>
</div>
<div class="paragraph">
<p><em>To test that Redis is functioning correctly, connect to the server using the command-line client</em>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ redis-cli</code></pre>
</div>
</div>
<div class="paragraph">
<p>In the prompt that follows, test connectivity with the ping command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">127.0.0.1:6379> ping</code></pre>
</div>
</div>
<div class="paragraph">
<p>Redis' response will be:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">PONG</code></pre>
</div>
</div>
<div class="paragraph">
<p>This output confirms that the server connection is still alive. Next, check that you’re able to set keys by running:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">127.0.0.1:6379> set test "It's working!"</code></pre>
</div>
</div>
<div class="paragraph">
<p>The outup will be:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">OK</code></pre>
</div>
</div>
<div class="paragraph">
<p>Retrieve the value by typing:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">127.0.0.1:6379> get test</code></pre>
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<p>Assuming everything is working, you will be able to retrieve the value you stored:</p>
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<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">"It's working!"</code></pre>
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<p>After confirming that you can fetch the value, exit the Redis prompt to get back to the shell:</p>
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<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">127.0.0.1:6379> exit</code></pre>
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<p>As a final test, we will check whether Redis is able to persist data even after it’s been stopped or restarted. To do this, first restart the Redis instance:</p>
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<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ sudo systemctl restart redis</code></pre>
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<p>Then connect with the command-line client once again and confirm that your test value is still available:</p>
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<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">$ redis-cli
127.0.0.1:6379> get test</code></pre>
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<p>The value of your key should still be accessible:</p>
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<pre class="highlightjs highlight"><code data-lang="console" class="language-console hljs">"It's working!"</code></pre>
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<p>Exit out into the shell again when you are finished:</p>
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