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setting_up_php.md

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Setting up PHP & Hello PHP site

PHP is one most versatile web languages around. It is also very simple to setup. There are various other web toolkits out there, but for the sake of simplicity of this tutorial we'll stick with PHP for now

Enable PHP on Apache

Let's update our apache manifest to include the Apache PHP plugin:

include apache
include apache::mod::php

and as usual, apply it via Puppet:

[root@my-first-app ~]# puppet apply apache-via-mod.pp
Notice: Compiled catalog for my-first-app.c.graphite-playground.google.com.internal in environment production in 1.36 seconds
Notice: /Stage[main]/Apache::Mod::Php/Apache::Mod[php5]/Package[php]/ensure: created
Notice: /Stage[main]/Apache/File[/etc/httpd/conf.d/php.conf]/ensure: removed
Notice: /Stage[main]/Apache::Mod::Php/File[php5.conf]/ensure: defined content as '{md5}24420bffd2939b1fe3ff0ca36dbad419'
Notice: /Stage[main]/Apache::Mod::Php/Apache::Mod[php5]/File[php5.load]/ensure: defined content as '{md5}5aabed26d29e38135b5157acff80a2a6'
Notice: /Stage[main]/Apache/File[/etc/httpd/conf.modules.d/10-php.conf]/ensure: removed
Notice: /Stage[main]/Apache::Service/Service[httpd]: Triggered 'refresh' from 1 events
Notice: Applied catalog in 4.51 seconds
[root@my-first-app ~]#

Puppet did all the necessary work to setup the necessary modules on your machine, including the necessary packages from the Operating System. Apache is now ready to take PHP content, so let's do it.

Update main website page

Let's replace our main "coming soon" page with a page that tells the time:

include apache
include apache::mod::php

# Let's get rid of the coming soon file
file { '/var/www/html/index.html':
  ensure => absent,
}

# Define our main website as a PHP page
file { '/var/www/html/index.php':
  ensure  => file,
  content => '<?php echo "Now it is " . date("r"); ?>', # echoes the time
}

... and apply ....

[root@my-first-app ~]# puppet apply php-sample.pp
Notice: Compiled catalog for my-first-app.c.graphite-playground.google.com.internal in environment production in 1.31 seconds
Notice: /Stage[main]/Main/File[/var/www/html/index.html]/ensure: removed
Notice: /Stage[main]/Main/File[/var/www/html/index.php]/ensure: defined content as '{md5}7b787125b1026cc7582f46a127f58115'
Notice: Applied catalog in 0.67 seconds
[root@my-first-app ~]#

Now refresh your browser (where the 'coming soon' page was showing) and you should see something like this:

Now it is Sun, 25 Jun 2017 07:38:19 +0000

Updating time zone

You will notice that the time is apparently not correct. Actually it is (the machine has its clock synced to an atomic clock). The "problem" is that it is showing the time in "UTC" (Greenwich) time zone "+0000".

PHP date('r') command draws the time zone from the machine, so we need to adjust the machine time zone accordingly. (There are more sophisticated ways of dealing with global time, but they are beyond this quick start tutorial).

You'll never guess: we'll be using Puppet to do that :) We'll write this Puppet manifest once and use it anytime we need. As before put it in your file and apply it using Puppet:

include apache
include apache::mod::php

file { '/etc/php.d/timezone.ini':
  ensure  => file,
  content => join([
      '[Date]',
      'date.timezone = America/Los_Angeles',
    ]),
  notify  => Class['apache::service'],
}

The expected output:

[root@my-first-app ~]# puppet apply time.php
Notice: Compiled catalog for my-first-app.c.graphite-playground.google.com.internal in environment production in 1.50 seconds
Notice: /Stage[main]/Main/File[/etc/php.d/timezone.ini]/ensure: defined content as '{md5}34cb0851c4094296a53415c09486c53d'
Notice: /Stage[main]/Apache::Service/Service[httpd]: Triggered 'refresh' from 1 events
Notice: Applied catalog in 1.80 seconds
[root@my-first-app ~]#

The include and file portions are not new. We're just creating another file that PHP will read to configure time zone (following PHP date.timezone docs). You can use any of the Supported Timezones described.

The new part here is the notify => line. This one is critical for you to understand as it is a core Puppet strength. This tells Puppet to notify the service (and reconfigure itself) if there are changes to the file being applied. Notice the Service[httpd]: Triggered 'refresh' in your apply output.

Why? PHP reads this file when the Apache web server starts up. That means if you create the file and put it there nothing happens until next time the Apache server restarts (or reloads gracefully).

What did Puppet do under the covers?

Puppet is now watching the file you defined, and if and only if there are changes to that file it will tell Apache to reload gracefully, picking up the changes.

Try without Puppet yourself

  1. Change /etc/php.d/php.ini to some other time zone
  2. Reload your web page
  3. You will notice that nothing changed
  4. Now execute systemctl restart httpd
  5. Reload the page on the browser
  6. Now it shows the correct time zones.

Puppet just did that for you without needing to resort to understanding which command on the operating system does that (systemctl is for Cent OS). Other operating systems uses different commands that you have to know to manage them. Note that you also did not need to know all the inner details of Apache or PHP get this this going.

[Pro Tip] Before you deploy your application for real (what we call production) I suggest you do understand better Apache and PHP. How to configure it properly: to run fast, secure, reliable. It sucks when you put your site and some hacker vandalizes it, or worse, steals all your data.

That's it for now. I hope you got the basis of what Puppet is great at.

Ah... added bonus: these manifests you wrote will run on any Linux operating system without changes. It is what we call portable code.